Topic Contents

Vitamin A

Uses

Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.

For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

3 Stars Reliable and relatively consistent scientific data showing a substantial health benefit.

2 Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.

1 Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

This supplement has been used in connection with the following health conditions:

Used for	Why
3 Stars Anemia 10,000 to 25,000 IU daily	Vitamin A deficiency can contribute to anemia, supplementing with this vitamin may restore levels and improve symptoms. Deficiencies of iron , vitamin B12 , and folic acid are the most common nutritional causes of anemia.¹ Although rare, severe deficiencies of several other vitamins and minerals, including vitamin A ,² ^{, 3} vitamin B2 ,⁴ vitamin B6 ,⁵ ^{, 6} vitamin C ,⁷ and copper ,⁸ ^{, 9} can also cause anemia by various mechanisms. Rare genetic disorders can cause anemias that may improve with large amounts of supplements such as vitamin B1 .¹⁰ ^{, 11}
3 Stars Childhood Diseases High doses of vitamin A may be used to treat measles or chicken pox, but only under a doctor's supervision	Vitamin A plays a critical role in proper immune function, it has been used successfully to prevent and treat measles and to treat chicken pox. Preliminary research shows that supplemental vitamin A improves the likelihood that the measles vaccine will provide protection.¹² Vitamin A has, since the 1920s, been the subject of much research into the prevention and treatment of childhood exanthems, particularly measles.¹³ This nutrient has a critical role in proper immune function , and there is evidence that supplementation with vitamin A reduces the incidence and severity of, and deaths from, childhood measles.¹⁴ ^{, 15} The World Health Organization (WHO) has therefore recommended that children with signs of deficiency receive supplementation with vitamin A. The recommended amounts are 100,000 IU for children younger than one year and 200,000 IU for children older than one year, immediately upon diagnosis, and repeated once the next day and once in one to four weeks.¹⁶ A controlled trial of African children given vitamin A supplementation according to the WHO’s recommendations found that severity of measles and its long-term consequences were reduced by 82% on day eight, 61% in week six, and 85% six months after the onset.¹⁷ Another controlled trial found that giving approximately 200,000 IU of vitamin A once during measles illness was not adequate to provide any benefit in African children whose vitamin A status was unknown.¹⁸ In a controlled prevention study, Indian children treated with 2,500 mcg (8,333 IU) of vitamin A weekly had fewer measles complications and less than half of the rate of death as compared with children receiving placebo;¹⁹ but in another study, Indian children receiving 200,000 IU of vitamin A every six months did not have a different rate of total infectious illness nor rate of death as compared with children receiving placebo.²⁰ An analysis of 20 controlled trials concluded that vitamin A supplementation reduced deaths from measles respiratory infection by 70%.²¹ While vitamin A deficiency is widespread in developing countries, it has also been reported in the United States and has been linked with more severe cases of measles.²² The American Academy of Pediatrics has recommended supplementation with vitamin A for children between the ages of six months and two years who are hospitalized with measles and its complications. The recommended amount is a single administration of 100,000 IU for children aged 6 to 12 months and 200,000 IU for children older than 1 year, followed by a second administration 24 hours later and a third after four weeks in children who are likely to have vitamin A deficiency.²³ One trial showed that low levels of vitamin A are more prevalent in children with measles than in similar children without measles, with levels rising back to normal several days after the onset of the infection. This observation led the authors of the study to conclude that vitamin A deficiency is a consequence of infection with the measles virus and to recommend supplementation with vitamin A during measles infection even when prior deficiency is not suspected.²⁴ Vitamin A stores have also been shown to be depleted during chicken pox infection,²⁵ and some preliminary data supports its use in treatment of chicken pox. In a controlled trial, in which children without vitamin A deficiency were given either 200,000 IU of vitamin A or placebo one time during chicken pox, the children given vitamin A had shorter duration of illness and fewer severe complications. The researchers then treated the patients’ siblings with vitamin A before chicken pox became evident, and they had an even shorter length of illness.²⁶
3 Stars Cystic Fibrosis 5,000 to 10,000 IU daily	The fat malabsorption associated with cystic fibrosis often leads to a deficiency of fat-soluble vitamins, such as vitamin A. Supplementing with this vitamin can help counteract the deficiency. The fat malabsorption associated with CF often leads to a deficiency of fat-soluble vitamins. Oral supplementation of these nutrients is considered crucial to maintaining good nutritional status.²⁷ Current recommendations for supplementation are as follows: vitamin A , 5,000 to 10,000 IU/day; vitamin D , 1,000 to 2,000 IU/day; vitamin E , 100 to 300 IU/day; and vitamin K , 5 mg every three days. Of the water-soluble vitamins, only vitamin B12 is poorly absorbed in cystic fibrosis,²⁸ and taking pancreatic enzymes helps prevent B12 deficiencies.²⁹
3 Stars Infection See a doctor for evaluation of possible deficiency	Vitamin A plays an important role in immune system function and helps mucous membranes, including those in the lungs, resist invasion by microorganisms. Nutrients useful for maintaining healthy immune function are also applicable for preventing infections. Vitamin A plays an important role in immune system function and helps mucous membranes, including those in the lungs, resist invasion by microorganisms.³⁰ However, most research shows that while vitamin A supplementation helps people prevent or treat infections in developing countries where deficiencies are common,³¹ little to no positive effect, and even slight adverse effects, have resulted from giving vitamin A supplements to people in countries where most people consume adequate amounts of vitamin A.³² ^{, 33} ^{, 34} ^{, 35} ^{, 36} ^{, 37} ^{, 38} Moreover, vitamin A supplementation during infections appears beneficial only in certain diseases. An analysis of trials revealed that vitamin A reduces mortality from measles and diarrhea , but not from pneumonia, in children living in developing countries.³⁹ A double-blind trial for vitamin A supplementation in Tanzanian children with pneumonia confirmed its lack of effectiveness for this condition.⁴⁰ In general, parents in the developed world should not give vitamin A supplements to children unless there is a reason to believe vitamin A deficiency is likely, such as the presence of a condition causing malabsorption (e.g., celiac disease ). However, the American Academy of Pediatrics recommends that all children with measles should be given high-dose vitamin A for several days.
3 Stars Leukoplakia 28,500 IU daily under medical supervision	Vitamin A has been shown to be effective against leukoplakia. Beta-carotene is the most widely used supplement in the treatment of leukoplakia. In a clinical trial of betel nut chewers with leukoplakia, supplementation with 150,000 IU of beta-carotene twice per week for six months significantly increased the remission rate compared with placebo (14.8% vs. 3.0%).⁴¹ The effectiveness of beta-carotene for treating leukoplakia was also confirmed in a double-blind trial that used 100,000 IU per day for six months.⁴² In one trial, supplementation with 33, 333 IU of beta-carotene per day, alone or combined with 50 IU of vitamin E , was reported not to reduce the incidence of leukoplakia.⁴³ These results have also been observed in smaller trials.⁴⁴ ^{, 45} Drug therapy with a synthetic, prescription form of vitamin A (known as Accutane®, isotretinoin , and 13-cis retinoic acid) has been reported to be more effective than treatment with 50,000 IU per day of beta-carotene.⁴⁶ However, because of the potential toxicity of the vitamin A-like drug, it may be preferable to treat leukoplakia with beta-carotene, which is much safer. Before the research on beta-carotene was published, vitamin A was used to treat leukoplakia.⁴⁷ One group of researchers reported that vitamin A (28,500 IU per day) was more effective than beta-carotene in treating people with leukoplakia.⁴⁸ Another trial found that the combination of 150,000 IU per week of beta-carotene plus 100,000 IU per week of vitamin A led to a significant increase in remission time compared to beta carotene alone in betel nut chewers.⁴⁹ Women who are or who could become pregnant should not take 100,000 IU of vitamin A per week without medical supervision.
3 Stars Measles 200,000 IU daily for two days under medical supervision	In developing countries where vitamin A deficiency is common, preventive supplementation with vitamin A reduced the risk of death in children with measles. Measles appears to increase the body’s need for vitamin A .⁵⁰ ^{, 51} Studies in developing countries have shown that measles infection is more frequent and severe in people with low vitamin A blood levels,⁵² ^{, 53} and preliminary research suggests this may also be true in the developed world.⁵⁴ ^{, 55} ^{, 56} Repeatedly in controlled trials, preventive supplementation with vitamin A, at oral doses of up to 400,000 IU per day, reduced the risk of death in children with measles living in developing countries.⁵⁷ ^{, 58} ^{, 59} Whether vitamin A supplementation would help people with measles in developed countries, where deficiency is uncommon, is less clear.⁶⁰ However, the American Academy of Pediatrics recommends that all children with measles be given a short course of high-dose vitamin A. Two controlled studies of urban South African⁶¹ and Japanese⁶² children hospitalized with severe measles showed that supplementation with 100,000 to 400,000 IU of vitamin A resulted in faster recoveries, fewer complications, and fewer pneumonia-related deaths. An older study in England found one ounce per day of cod liver oil (containing about 40,000 IU of vitamin A, plus vitamin D and omega-3 fatty acids) reduced measles-related deaths in children hospitalized with severe cases of the disease.⁶³ Such large doses of vitamin A should only be taken under a doctor’s supervision.
3 Stars Night Blindness If deficient: 10,000 to 25,000 IU daily	Night blindness may be an early sign of vitamin A deficiency. Doctors often recommend supplementing with vitamin A per day to correct a deficiency. Night blindness may be an early sign of vitamin A deficiency. Such a deficiency may result from diets low in animal foods (the main source of vitamin A), such as eggs, dairy products, organ meats, and some fish. Low intake of fruits and vegetables containing beta-carotene , which the body converts into vitamin A, may also contribute to a vitamin A deficiency. Doctors often recommend 10,000 to 25,000 IU of vitamin A per day to correct a deficiency. Beta-carotene is less effective at correcting vitamin A deficiency than is vitamin A itself, because it is not absorbed as well and is only slowly converted by the body into vitamin A.
2 Stars Celiac Disease Consult a qualified healthcare practitioner	Vitamin A deficiency may occur as a result of celiac disease, in which case vitamin A supplements or injections can be beneficial. In one study, six people with diet-treated celiac disease had abnormal dark-adaptation tests (indicative of “night blindness”), even though some were taking a multivitamin that contained vitamin A . Some of these people showed an improvement in dark adaptation after receiving larger amounts of vitamin A, either orally or by injection.⁶⁴ People with celiac disease should discuss the possibility of vitamin A deficiency with a healthcare practitioner before taking vitamin A supplements.
2 Stars Heart Attack 50,000 IU daily	Taking vitamin A may reduce heart attack risk and may improve the outcome for people who have already had a heart attack. Blood levels of the antioxidant nutrients vitamins A, C, and E, and beta-carotene are reported to be lower in people with a history of heart attack, compared with healthy individuals.⁶⁵ The number of free radical molecules is also higher, suggesting a need for antioxidants. Streptokinase, a drug therapy commonly used immediately following a heart attack, enhances the need for antioxidants.⁶⁶ Taking antioxidant supplements may improve the outcome for people who have already had a heart attack. In one double-blind trial, people were given 50,000 IU of vitamin A per day, 1,000 mg of vitamin C per day, 600 IU of vitamin E per day, and approximately 41,500 IU of beta-carotene per day or placebo.⁶⁷ After 28 days, the infarct size of those receiving antioxidants was significantly smaller than the infarct size of the placebo group. Low levels of beta-carotene in fatty tissue have been linked to an increased incidence of heart attacks, particularly among smokers.⁶⁸ One population study found that eating a diet high in beta-carotene is associated with a lower rate of nonfatal heart attacks.⁶⁹ However, beta-carotene supplementation may not offer the same protection provided by foods that contain beta-carotene. Most,⁷⁰ ^{, 71} but not all, trials⁷² have found that supplemental beta-carotene is not associated with a reduced risk of heart attacks.
2 Stars Immune Function Consult a qualified healthcare practitioner	Vitamin A plays an important role in immune system function and helps mucous membranes, including those in the lungs, resist invasion by microorganisms. Vitamin A plays an important role in immune system function and helps mucous membranes, including those in the lungs, resist invasion by microorganisms.⁷³ However, most research shows that while vitamin A supplementation helps people prevent or treat infections in developing countries where deficiencies are common,⁷⁴ little to no positive effect, and even slight adverse effects, have resulted from giving vitamin A supplements to people in countries where most people consume adequate amounts of vitamin A.⁷⁵ ^{, 76} ^{, 77} ^{, 78} ^{, 79} ^{, 80} ^{, 81} Moreover, vitamin A supplementation during infections appears beneficial only in certain diseases. An analysis of trials revealed that vitamin A reduces mortality from measles and diarrhea , but not from pneumonia, in children living in developing countries.⁸² A double-blind trial of vitamin A supplementation in Tanzanian children with pneumonia confirmed its lack of effectiveness for this condition.⁸³ In general, parents in the developed world should not give vitamin A supplements to children unless there is a reason to believe vitamin A deficiency is likely, such as the presence of a condition causing malabsorption (e.g., celiac disease ). However, the American Academy of Pediatrics recommends that all children with measles be given short-term supplementation with high-dose vitamin A in cases of hospitalization, malnutrition, and other special circumstances determined by a doctor.⁸⁴ A combination of antioxidants vitamin A , vitamin C , and vitamin E significantly improved immune cell number and activity compared with placebo in a group of hospitalized elderly people.⁸⁵ Daily intake of a 1,000 mg vitamin C plus 200 IU vitamin E for four months improved several measures of immune function in a preliminary study.⁸⁶ To what extent immune-boosting combinations of antioxidants actually reduce the risk of infection remains unknown.
2 Stars Menorrhagia 50,000 IU of vitamin A each day taken under the supervision of a doctor	In one study, women with menorrhagia who took vitamin A showed significant improvement or complete normalization of menstrual blood loss. In a study of women with menorrhagia who took 25,000 IU of vitamin A twice per day for 15 days, 93% showed significant improvement and 58% had a complete normalization of menstrual blood loss.⁸⁷ However, women who are or could become pregnant should not supplement with more than 10,000 IU (3,000 mcg) per day of vitamin A.
2 Stars Peptic Ulcer Take under medical supervision: 150,000 IU per day	Vitamin A is needed to heal the linings of the stomach and intestines. In one trial, supplementing with vitamin A improved healing in a small group of people with stomach ulcer. Vitamin A is needed to heal the linings (called mucous membranes) of the stomach and intestines. In one controlled trial, vitamin A supplementation facilitated healing in a small group of people with stomach ulcer.⁸⁸ The amount used in that study (150,000 IU per day) can be toxic and may also cause birth defects. Such a high dose should not be taken by a pregnant woman, by a woman who could become pregnant , or by anyone else without careful supervision from a doctor. Objective evidence of ulcer healing from taking vitamin A has been reported by the same research group.⁸⁹ The effect of lower amounts of vitamin A has not been studied in people with peptic ulcer.
2 Stars Severe Measles Consult a qualified healthcare practitioner	Two studies of children with severe measles showed that supplementing with high doses vitamin A speeded recovery and reduced complications and pneumonia-related deaths. Vitamin A has a critical role in proper immune function , and evidence suggests that supplementing with it reduces the incidence and severity of, and deaths from, childhood measles.⁹⁰ ^{, 91} The World Health Organization (WHO) has therefore recommended that children with signs of deficiency receive supplementation with vitamin A. The recommended amounts are 100,000 IU for children younger than one year and 200,000 IU for children older than one year, immediately upon diagnosis, and repeated once the next day and once in one to four weeks.⁹² A controlled trial of African children given vitamin A supplementation according to the WHO’s recommendations found that severity of measles and its long-term consequences were reduced by 82% on day eight, 61% in week six, and 85% six months after the onset.⁹³ Another controlled trial found that giving approximately 200,000 IU of vitamin A once during measles illness was not adequate to provide any benefit in African children whose vitamin A status was unknown.⁹⁴ In a controlled prevention study, Indian children treated with 2,500 mcg (8,333 IU) of vitamin A weekly had fewer measles complications and less than half of the rate of death as compared with children receiving placebo;⁹⁵ but in another study, Indian children receiving 200,000 IU of vitamin A every six months did not have a different rate of total infectious illness nor rate of death as compared with children receiving placebo.⁹⁶ An analysis of 20 controlled trials concluded that vitamin A supplementation reduced deaths from measles respiratory infection by 70%.⁹⁷ While vitamin A deficiency is widespread in developing countries, it has also been reported in the United States and has been linked with more severe cases of measles.⁹⁸ The American Academy of Pediatrics has recommended supplementation with vitamin A for children between the ages of six months and two years who are hospitalized with measles and its complications. The recommended amount is a single administration of 100,000 IU for children aged 6 to 12 months and 200,000 IU for children older than 1 year, followed by a second administration 24 hours later and a third after four weeks in children who are likely to have vitamin A deficiency.⁹⁹ One trial showed that low levels of vitamin A are more prevalent in children with measles than in similar children without measles, with levels rising back to normal several days after the onset of the infection. This observation led the authors of the study to conclude that vitamin A deficiency is a consequence of infection with the measles virus and to recommend supplementation with vitamin A during measles infection even when prior deficiency is not suspected.¹⁰⁰ Vitamin A stores have also been shown to be depleted during chicken pox infection,¹⁰¹ and some preliminary data supports its use in treatment of chicken pox. In a controlled trial, in which children without vitamin A deficiency were given either 200,000 IU of vitamin A or placebo one time during chicken pox, the children given vitamin A had shorter duration of illness and fewer severe complications. The researchers then treated the patients’ siblings with vitamin A before chicken pox became evident, and they had an even shorter length of illness.¹⁰²
2 Stars Wound Healing Take under medical supervision: 25,000 IU daily	Vitamin A plays a central role in wound healing and may be useful as a supplement or in a topical ointment. Vitamin A plays a central role in wound healing,¹⁰³ but the effect of supplemental vitamin A in people who have suffered a minor injury and are not vitamin A-deficient remains unclear. Vitamin A supplements have been shown to improve healing in animal studies,¹⁰⁴ and may be especially useful in a topical ointment for skin injuries in people taking corticosteroid medications.¹⁰⁵ Although there are no studies in humans, some doctors recommend 25,000 IU of vitamin A per day, beginning two weeks prior to surgery and continuing for four weeks after surgery.
1 Star Abnormal Pap Smear Refer to label instructions	Women who don’t get enough vitamin A have an increased risk of cervical dysplasia, though there is little research on using vitamin A as a treatment. Women with a low intake of vitamin A have an increased risk of cervical dysplasia.¹⁰⁶ However, there is little research on the use of vitamin A as a treatment for cervical dysplasia.
1 Star Acne Vulgaris Refer to label instructions	Under medical supervision, large quantities of vitamin A have been used successfully to treat severe acne. However, the acne typically returns after treatment is discontinued. Large quantities of vitamin A —such as 300,000 IU per day for females and 400,000–500,000 IU per day for males—have been used successfully to treat severe acne.¹⁰⁷ However, unlike the long-lasting benefits of the synthetic prescription version of vitamin A ( isotretinoin as Accutane), the acne typically returns several months after natural vitamin A is discontinued. In addition, the large amounts of vitamin A needed to control acne can be toxic and should be used only under careful medical supervision.
1 Star Alcohol Withdrawal Refer to label instructions	Because of potential liver damage, correcting the vitamin A deficiency common to alcoholics requires a doctor’s supervision to monitor liver function. Although the incidence of B-complex deficiencies is known to be high in alcoholics, the incidence of other vitamin deficiencies remains less clear.¹⁰⁸ Nonetheless, deficiencies of vitamin A , vitamin D , vitamin E , and vitamin C are seen in many alcoholics. While some reports have suggested it may be safer for alcoholics to supplement with beta-carotene instead of vitamin A,¹⁰⁹ potential problems accompany the use of either vitamin A or beta-carotene in correcting the deficiency induced by alcoholism.¹¹⁰ These problems result in part because the combinations of alcohol and vitamin A or alcohol and beta-carotene appear to increase potential damage to the liver. Thus, vitamin A-depleted alcoholics require a doctor’s intervention, including supplementation with vitamin A and beta-carotene accompanied by assessment of liver function. Supplementing with vitamin C, on the other hand, appears to help the body rid itself of alcohol.¹¹¹ Some doctors recommend 1 to 3 grams per day of vitamin C.
1 Star Conjunctivitis and Blepharitis Refer to label instructions	Vitamin A deficiency has been reported in people with chronic conjunctivitis, but it is unknown whether vitamin A supplementation can help the condition. Vitamin A deficiency has been reported in people with chronic conjunctivitis.¹¹² It is unknown whether vitamin A supplementation can prevent conjunctivitis or help people who already have the condition.
1 Star Crohn’s Disease Refer to label instructions	Vitamin A is needed for the growth and repair of cells that line both the small and large intestine and can improve symptoms in people with Crohn’s disease. Vitamin A is needed for the growth and repair of cells that line both the small and large intestine.¹¹³ At least two case reports describe people with Crohn’s disease who have responded to vitamin A supplementation.¹¹⁴ ^{, 115} However, in one trial, vitamin A supplementation failed to maintain remission of the disease.¹¹⁶ Therefore, although some doctors recommend 50,000 IU per day for adults with Crohn’s disease, this approach remains unproven. An amount this high should never be taken without qualified guidance, nor should it be given to a woman who is or could become pregnant .
1 Star Diarrhea Refer to label instructions	Only in cases of malabsorption should vitamin A be used to treat diarrhea, as it has been shown to have no effect or to increase risk of diarrhea in well-nourished children. It is known vitamin A supplements support immune function and prevent infections. This is true, however, only under some circumstances. Vitamin A supplementation can also increase the risk of infections, according to the findings of a double-blind trial.¹¹⁷ In a study of African children between six months and five years old, a 44% reduction in the risk of severe diarrhea was seen in those children given four 100,000–200,000 IU supplements of vitamin A (the lower amount for those less than a year old) during an eight-month period. On further investigation, the researchers discovered that the reduction in diarrhea occurred only in children who were very malnourished. For children who were not starving, vitamin A supplementation actually increased the risk of diarrhea compared with the placebo group. The vitamin A-supplemented children also had a 67% increased risk of coughing and rapid breathing, and signs of further lung infection, although this problem did not appear in children infected with the AIDS virus. These findings should be of concern to American parents, whose children are not usually infected with HIV or severely malnourished. Such relatively healthy children fared poorly in the African trial in terms of both the risk of diarrhea and the risk of continued lung problems. Vitamin A provided no benefit to the well-nourished kids. Therefore, it makes sense not to give vitamin A supplements to children unless there is a special reason to do so, such as the presence of a condition causing malabsorption (e.g., celiac disease ).
1 Star Gastritis Refer to label instructions	Vitamin A appears to reduce ulcer size and pain in people with ulcers and may help treat gastritis. Zinc and vitamin A , nutrients that aid in healing, are commonly used to help people with peptic ulcers. For example, the ulcers of people taking 50 mg of zinc three times per day healed three times faster than those of people who took placebo.¹¹⁸ Since some types of gastritis can progress to peptic ulcer, it is possible that taking it may be useful. Nevertheless, the research does not yet show that zinc specifically helps people with gastritis. The amount of zinc used in this study is very high compared with what most people take (15–40 mg per day). Even at these lower levels, it is necessary to take 1–3 mg of copper per day to avoid a zinc-induced copper deficiency.
1 Star Goiter Refer to label instructions	Vitamin A levels are lower in people with goiter than in those without. A combination of vitamin C, vitamin E, and beta-carotene prevented goiter formation in iodine-deficient conditions in some research. Blood levels of vitamin A are lower in people with goiter than in similar people without goiter.¹¹⁹ ^{, 120} The same relationship has been found for vitamin E and goiter.¹²¹ Animal research has found that, in iodine-deficient conditions, a supplement combination of vitamin C , vitamin E, and beta-carotene prevented goiter formation (though hypothyroidism was not improved), and vitamin E alone had a similar effect.¹²² No studies have been done to investigate this benefit in humans.
1 Star HIV and AIDS Support Refer to label instructions	Vitamin A deficiency is common in people with HIV infection, and low levels of the vitamin are associated with greater disease severity. Ask your doctor if vitamin A is right for you. Vitamin A deficiency appears to be very common in people with HIV infection. Low blood levels of vitamin A are associated with greater disease severity¹²³ and increased transmission of the virus from a pregnant mother to her infant.¹²⁴ However, in preliminary ¹²⁵ and double-blind¹²⁶ ^{, 127} trials, supplementation with vitamin A failed to reduce the overall mother-to-child transmission of HIV. HIV-positive women who took 5,000 IU per day of vitamin A (as retinyl palmitate) and 50,000 IU per day of beta-carotene during the third trimester (13 weeks) of pregnancy, plus an additional single amount of 200,000 IU of vitamin A at delivery, had the same rate of transmission of HIV to their infants as those who did not take the supplement. However, lower rates of illness have been observed in the children of HIV-positive mothers when the children were supplemented with 50,000–200,000 IU of vitamin A every two to three months.¹²⁸ Little research has explored whether vitamin A supplements are helpful at halting disease progression. HIV-positive children given two consecutive oral supplements of vitamin A (200,000 IU in a gelcap) in the two days following influenza vaccinations had a modest but significant decrease in viral load.¹²⁹ In one trial, giving people an extremely high (300,000 IU) amount of vitamin A one time only did not improve short-term measures of immunity in women with HIV.¹³⁰
1 Star Hypothyroidism Refer to label instructions	People with hypothyroidism may have an impaired ability to convert beta-carotene to vitamin A. For this reason, some doctors suggest supplementing with vitamin A. People with hypothyroidism have been shown to have an impaired ability to convert beta-carotene to vitamin A .¹³¹ ^{, 132} For this reason, some doctors suggest taking supplemental vitamin A (approximately 5,000–10,000 IU per day) if they are not consuming adequate amounts in their diet.
1 Star Pre- and Post-Surgery Health Refer to label instructions	Topical vitamin A may help speed wound healing and reduce scarring in patients taking corticosteroids, which typically slow wound healing. Vitamin A plays an important role in wound healing ,¹³³ and one animal study suggests that vitamin A deficiency might contribute to poor recovery after surgery.¹³⁴ Vitamin A may be particularly beneficial to post-surgical patients who are using corticosteroid medications. These medications typically slow wound healing, and a number of animal studies have found that both topical and oral vitamin A reverse this effect; however, vitamin A does not change healing time in animals not given corticosteroids.¹³⁵ ^{, 136} ^{, 137} Similar results have been reported for topical vitamin A in some human cases, and these researchers suggest a topical preparation containing 200,000 IU of vitamin A per ounce for improved surgical wound healing in patients using corticosteroids after surgery.¹³⁸ Topical vitamin A may also reduce scarring in patients taking corticosteroids.¹³⁹
1 Star Premenstrual Syndrome Refer to label instructions	Very high amounts of vitamin A have reduced PMS symptoms in some studies. Very high amounts of vitamin A—100,000 IU per day or more—have reduced symptoms of PMS,¹⁴⁰ ^{, 141} but such an amount can cause serious side effects with long-term use. Women who are or who could become pregnant should not supplement with more than 10,000 IU (3,000 mcg) per day of vitamin A. Other people should not take more than 25,000 IU per day without the supervision of their doctor. As yet, no trials have explored the effects of these safer amounts of vitamin A in women suffering from PMS.
1 Star Sickle Cell Anemia Refer to label instructions	Sickle cell anemia patients tend to have low levels of antioxidants, which protect cells from oxygen-related damage. Supplementing with vitamin A may help correct a deficiency. Antioxidant nutrients protect the body’s cells from oxygen-related damage. Many studies show that sickle cell anemia patients tend to have low blood levels of antioxidants, including carotenoids , vitamin A , vitamin E , and vitamin C , despite adequate intake.¹⁴² ^{, 143} ^{, 144} ^{, 145} ^{, 146} ^{, 147} Low blood levels of vitamin E in particular have been associated with higher numbers of diseased cells in children¹⁴⁸ and with greater frequency of symptoms in adults.¹⁴⁹ A small, preliminary trial reported a 44% decrease in the average number of diseased cells in six sickle cell anemia patients given 450 IU vitamin E per day for up to 35 weeks. This effect was maintained as long as supplementation continued.¹⁵⁰
1 Star Type 1 Diabetes (Selenium, Vitamin C, Vitamin E) Refer to label instructions	A combination of the antioxidants selenium, vitamin A, vitamin C, and vitamin E has been shown to improve diabetic retinopathy. Because oxidation damage is believed to play a role in the development of diabetic eye damage ( retinopathy ), antioxidant nutrients might be protective. One doctor has administered a daily regimen of 500 mcg selenium , 800 IU vitamin E , 10,000 IU vitamin A , and 1,000 mg vitamin C for several years to 20 people with diabetic eye damage ( retinopathy ). During that time, 19 of the 20 people showed either improvement or no progression of their retinopathy.¹⁵¹ People who wish to supplement with more than 250 mcg of selenium per day should consult a healthcare practitioner.
1 Star Type 1 Diabetes and Diabetic Retinopathy (Selenium, Vitamin C, Vitamin E) Refer to label instructions	Antioxidant nutrients including selenium, vitamin A, vitamin C, and vitamin E may combat free radicals associated with diabetic retinopathy. Because oxidation damage is believed to play a role in the development of diabetic eye damage ( retinopathy ), antioxidant nutrients might be protective. One doctor has administered a daily regimen of 500 mcg selenium , 800 IU vitamin E , 10,000 IU vitamin A , and 1,000 mg vitamin C for several years to 20 people with diabetic eye damage ( retinopathy ). During that time, 19 of the 20 people showed either improvement or no progression of their retinopathy.¹⁵² People who wish to supplement with more than 250 mcg of selenium per day should consult a healthcare practitioner.
1 Star Type 2 Diabetes and Diabetic Neuropathy (Selenium, Vitamin C, Vitamin E) Refer to label instructions	A combination of the antioxidants selenium, vitamin A, vitamin C, and vitamin E has been shown to improve diabetic retinopathy. Because oxidation damage is believed to play a role in the development of diabetic retinopathy, antioxidant nutrients might be protective. One doctor has administered a daily regimen of 500 mcg selenium , 800 IU vitamin E , 10,000 IU vitamin A , and 1,000 mg vitamin C for several years to 20 people with diabetic retinopathy. During that time, 19 of the 20 people showed either improvement or no progression of their retinopathy.¹⁵³ People who wish to supplement with more than 250 mcg of selenium per day should consult a healthcare practitioner.
1 Star Urinary Tract Infection Refer to label instructions	Vitamin A deficiency increases the risk of many infection, supplementing with it may restore levels and help support the immune system. Vitamin A deficiency increases the risk of many infections. Although much of the promising research with vitamin A supplements and infections has focused on measles,¹⁵⁴ vitamin A is also thought to be helpful in other infections. Some doctors recommend that people with urinary tract infections take vitamin A. A typical amount recommended to correct a deficiency is 10,000 to 25,000 IU per day.
1 Star Vaginitis Refer to label instructions	Some doctors recommend vaginal administration of vitamin A to improve the integrity of the vaginal tissue and to enhance the function of local immune cells. Some doctors recommend vitamin E (taken orally, topically, or vaginally) for certain types of vaginitis. Vitamin E as a suppository in the vagina or vitamin E oil can be used once or twice per day for 3 to 14 days to soothe the mucous membranes of the vagina and vulva. Some doctors recommend vaginal administration of vitamin A to improve the integrity of the vaginal tissue and to enhance the function of local immune cells. Vitamin A can be administered vaginally by inserting a vitamin A capsule or using a prepared vitamin A suppository. Vitamin A used this way can be irritating to local tissue, so it should not be used more than once per day for up to seven consecutive days.
0 Stars Sunburn (Vitamin D) Refer to label instructions	Antioxidants may protect the skin from sunburn due to free radical –producing ultraviolet rays.¹⁵⁵ Combinations of 1,000 to 2,000 IU per day of vitamin E and 2,000 to 3,000 mg per day of vitamin C , but neither given alone, have a significant protective effect against ultraviolet rays, according to double-blind studies.¹⁵⁶ ^{, 157} ^{, 158} Oral synthetic beta-carotene alone was not found to provide effective protection when given in amounts of 15 mg per day or for only a few weeks’ time in larger amounts of 60 to 90 mg per day, but it has been effective either in very large (180 mg per day) amounts or in smaller amounts (30 mg per day) in combination with topical sunscreen.¹⁵⁹ ^{, 160} ^{, 161} ^{, 162} ^{, 163} Natural sources of beta-carotene or other carotenoids have been more consistently shown to protect against sunburn. One controlled study found that taking a supplement of natural carotenoids (almost all of which was beta-carotene) in daily amounts of 30 mg, 60 mg, and 90 mg gave progressively more protection against ultraviolet rays.¹⁶⁴ In another controlled study, either 24 mg per day of natural beta-carotene or 24 mg per day of a carotenoid combination of equal amounts beta-carotene, lutein , and lycopene helped protect skin from ultraviolet rays.¹⁶⁵ A preliminary study compared synthetic lycopene (10.1 mg per day), a natural tomato extract containing 9.8 mg of lycopene per day plus additional amounts of other carotenoids, and a solubilized tomato drink (designed to increase lycopene absorption) containing 8.2 mg of lycopene plus additional amounts of other carotenoids. After 12 weeks, only the two tomato-based products were shown to give significant protection against burning by ultraviolet light.¹⁶⁶ Still other trials have tested combinations of several antioxidants . One preliminary study found that a daily combination of beta-carotene (6 mg), lycopene (6 mg), vitamin E (15 IU), and selenium for seven weeks protected against ultraviolet light.¹⁶⁷ However, a double-blind trial of a combination of smaller amounts of several carotenoids , vitamins C and E, selenium, and proanthocyanidins did not find significant UV protection compared with placebo.¹⁶⁸ Similarly, in a controlled trial, a combination of selenium, copper , and vitamins was found to be ineffective.¹⁶⁹ It should be noted that while oral protection from sunburn has been demonstrated with several types of antioxidants , the degree of protection (typically less than an SPF of 2) is much less than that provided by currently available topical sunscreens. On the other hand, these modest effects will provide some added protection to skin areas where sunscreen is also used and will give a small amount of protection to sun-exposed areas where sunscreen is not applied. However, oral protection from sunburn is not instantaneous; maximum effects are not reached until these antioxidants have been used for about eight to ten weeks.¹⁷⁰ ^{, 171}
0 Stars Sunburn (Vitamin E) Refer to label instructions	Antioxidants may protect the skin from sunburn due to free radical –producing ultraviolet rays.¹⁷² Combinations of 1,000 to 2,000 IU per day of vitamin E and 2,000 to 3,000 mg per day of vitamin C , but neither given alone, have a significant protective effect against ultraviolet rays, according to double-blind studies.¹⁷³ ^{, 174} ^{, 175} Oral synthetic beta-carotene alone was not found to provide effective protection when given in amounts of 15 mg per day or for only a few weeks’ time in larger amounts of 60 to 90 mg per day, but it has been effective either in very large (180 mg per day) amounts or in smaller amounts (30 mg per day) in combination with topical sunscreen.¹⁷⁶ ^{, 177} ^{, 178} ^{, 179} ^{, 180} Natural sources of beta-carotene or other carotenoids have been more consistently shown to protect against sunburn. One controlled study found that taking a supplement of natural carotenoids (almost all of which was beta-carotene) in daily amounts of 30 mg, 60 mg, and 90 mg gave progressively more protection against ultraviolet rays.¹⁸¹ In another controlled study, either 24 mg per day of natural beta-carotene or 24 mg per day of a carotenoid combination of equal amounts beta-carotene, lutein , and lycopene helped protect skin from ultraviolet rays.¹⁸² A preliminary study compared synthetic lycopene (10.1 mg per day), a natural tomato extract containing 9.8 mg of lycopene per day plus additional amounts of other carotenoids, and a solubilized tomato drink (designed to increase lycopene absorption) containing 8.2 mg of lycopene plus additional amounts of other carotenoids. After 12 weeks, only the two tomato-based products were shown to give significant protection against burning by ultraviolet light.¹⁸³ Still other trials have tested combinations of several antioxidants . One preliminary study found that a daily combination of beta-carotene (6 mg), lycopene (6 mg), vitamin E (15 IU), and selenium for seven weeks protected against ultraviolet light.¹⁸⁴ However, a double-blind trial of a combination of smaller amounts of several carotenoids , vitamins C and E, selenium, and proanthocyanidins did not find significant UV protection compared with placebo.¹⁸⁵ Similarly, in a controlled trial, a combination of selenium, copper , and vitamins was found to be ineffective.¹⁸⁶ It should be noted that while oral protection from sunburn has been demonstrated with several types of antioxidants , the degree of protection (typically less than an SPF of 2) is much less than that provided by currently available topical sunscreens. On the other hand, these modest effects will provide some added protection to skin areas where sunscreen is also used and will give a small amount of protection to sun-exposed areas where sunscreen is not applied. However, oral protection from sunburn is not instantaneous; maximum effects are not reached until these antioxidants have been used for about eight to ten weeks.¹⁸⁷ ^{, 188}

How It Works

How to Use It

For most people, up to 25,000 IU (7,500 mcg) of vitamin A per day is considered safe. However, people over age 65 and those with liver disease should probably not supplement with more than 15,000 IU per day, unless supervised by a doctor. In women who could become pregnant , the maximum safe intake is being re-evaluated. However, less than 10,000 IU (3,000 mcg) per day is generally accepted as safe. There is concern that larger intakes could cause birth defects . Whether the average person would benefit from vitamin A supplementation remains unclear.

Where to Find It

Liver, dairy products, and cod liver oil are good sources of vitamin A. Vitamin A is also available in supplement form.

Possible Deficiencies

People who limit their consumption of liver, dairy foods, and beta-carotene -containing vegetables can develop a vitamin A deficiency. Extremely low birth weight babies (2.2 pounds or less) are at high risk of being born with a deficiency, and vitamin A shots given to these infants have been reported in double-blind research to reduce the risk of lung disease.¹⁸⁹ The earliest deficiency sign is poor night vision . Deficiency symptoms can also include dry skin, increased risk of infections , and metaplasia (a precancerous condition). Severe deficiencies causing blindness are extremely rare in Western societies.

Less severe deficiencies are more likely to occur with a variety of conditions causing malabsorption . A high incidence of vitamin A deficiency in people infected with HIV has also been reported. People with hypothyroidism have an impaired ability to convert beta-carotene to vitamin A.¹⁹⁰ ^{, 191} For this reason, some doctors suggest taking supplemental vitamin A (perhaps 5,000–10,000 IU per day) if they are not consuming adequate amounts in their diet.

Very old people with type 2 diabetes have shown a significant age-related decline in blood levels of vitamin A, irrespective of their dietary intake.¹⁹²

Interactions

Interactions with Supplements, Foods, & Other Compounds

Taking vitamin A and iron together helps overcome iron deficiency more effectively than iron supplementation alone.¹⁹³ Supplementation with zinc , iron, or the combination has been found to improve vitamin A status among children at high risk for deficiency of the three nutrients.¹⁹⁴

Interactions with Medicines

Certain medicines interact with this supplement.

What Are Drug Interactions

Types of interactions: Beneficial Adverse Check

Replenish Depleted Nutrients

Carbamazepine

Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.²⁰¹ Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.
Cholestyramine

Bile acid sequestrants may prevent absorption of folic acid and the fat-soluble vitamins A , D , E , and K .²²⁰ ^{, 221} Other medications and vitamin supplements should be taken one hour before or four to six hours after bile acid sequestrants for optimal absorption.²²² Animal studies suggest calcium and zinc may also be depleted by taking cholestyramine.²²³
Colesevelam

Bile acid sequestrants may prevent absorption of folic acid and the fat-soluble vitamins A , D , E , and K .²³⁰ ^{, 231} Other medications and vitamin supplements should be taken one hour before or four to six hours after bile acid sequestrants for optimal absorption.²³² Animal studies suggest calcium and zinc may also be depleted by taking cholestyramine.²³³
Colestipol

Bile acid sequestrants, including colestipol, may prevent absorption of folic acid and the fat-soluble vitamins A , D , E , K .²³⁴ ^{, 235} People taking colestipol should consult with their doctor about vitamin malabsorption and supplementation. People should take other drugs and vitamin supplements one hour before or four to six hours after colestipol to improve absorption.²³⁶

Animal studies suggest calcium and zinc may be depleted by taking cholestyramine, another bile acid sequestrant. ²³⁷ Whether these same interactions would occur with colestipol is not known.
Felbamate

Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.²⁵¹ Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.
Gabapentin

Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.²⁶⁴ Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Levetiracetam

Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.²⁷⁷ Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.
Mineral Oil

Mineral oil has interfered with the absorption of many nutrients, including beta-carotene , calcium , phosphorus , potassium , and vitamins A , D , K , and E in some,³⁰² but not all,³⁰³ research. Taking mineral oil on an empty stomach may reduce this interference. It makes sense to take a daily multivitamin-mineral supplement two hours before or after mineral oil. It is important to read labels, because many multivitamins do not contain vitamin K or contain inadequate (less than 100 mcg per day) amounts.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Neomycin

Neomycin can decrease absorption or increase elimination of many nutrients, including calcium , carbohydrates, beta-carotene , fats, folic acid , iron , magnesium , potassium , sodium, and vitamin A , vitamin B12 , vitamin D , and vitamin K .³⁰⁴ ^{, 305} Surgery preparation with oral neomycin is unlikely to lead to deficiencies. It makes sense for people taking neomycin for more than a few days to also take a multivitamin-mineral supplement.
Orlistat

In one well-controlled study, taking orlistat for six months resulted in reduced blood levels of vitamins A and D, though levels for most individuals remained within the normal range. However, a few people developed levels low enough to require supplementation.³⁰⁶ Other studies have shown that taking orlistat had no affect on blood vitamin A levels.³⁰⁷ ^{, 308} Although additional research is needed, the current evidence suggests that individuals taking orlistat for more than six months should supplement with vitamins A and D.
Oxcarbazepine

Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.³⁰⁹ Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.
Phenobarbital

Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.³¹⁰ Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Phenytoin

Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.³¹¹ Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.
Thioridazine

A review of people taking thioridazine showed that they had higher blood levels of vitamin A than did individuals not using the drug.³²⁷ More research is necessary to determine whether taking vitamin A supplements with thioridazine might cause dangerously high vitamin A levels. Until more is known, people taking thioridazine should exercise caution with vitamin A supplementation and be alert for side effects such as bone pain, headaches, dry scaly skin, and hair loss.
Topiramate

Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.³³⁴ Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.
Valproate

Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.³⁴¹ Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Zonisamide

Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.³⁴⁸ Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.

Reduce Side Effects

Busulfan

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.¹⁹⁵ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.¹⁹⁶ Vitamin C appears to increase the effectiveness of chemotherapy in animals¹⁹⁷ and with human breast cancer cells in test tube research.¹⁹⁸ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.¹⁹⁹

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.²⁰⁰ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Carboplatin

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.²⁰² However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.²⁰³ Vitamin C appears to increase the effectiveness of chemotherapy in animals²⁰⁴ and with human breast cancer cells in test tube research.²⁰⁵ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.²⁰⁶

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.²⁰⁷ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.
Carmustine

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.²⁰⁸ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.²⁰⁹ Vitamin C appears to increase the effectiveness of chemotherapy in animals²¹⁰ and with human breast cancer cells in test tube research.²¹¹ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.²¹²

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.²¹³ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Chlorambucil

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.²¹⁴ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.²¹⁵ Vitamin C appears to increase the effectiveness of chemotherapy in animals²¹⁶ and with human breast cancer cells in test tube research.²¹⁷ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.²¹⁸

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.²¹⁹ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Cladribine

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.²²⁴ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.²²⁵ Vitamin C appears to increase the effectiveness of chemotherapy in animals²²⁶ and with human breast cancer cells in test tube research.²²⁷ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.²²⁸

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.²²⁹ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Erlotinib

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.²⁴⁵ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.²⁴⁶ Vitamin C appears to increase the effectiveness of chemotherapy in animals²⁴⁷ and with human breast cancer cells in test tube research.²⁴⁸ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.²⁴⁹

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.²⁵⁰ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Floxuridine

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.²⁵² However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.²⁵³ Vitamin C appears to increase the effectiveness of chemotherapy in animals²⁵⁴ and with human breast cancer cells in test tube research.²⁵⁵ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.²⁵⁶

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.²⁵⁷ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Fludarabine

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.²⁵⁸ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.²⁵⁹ Vitamin C appears to increase the effectiveness of chemotherapy in animals²⁶⁰ and with human breast cancer cells in test tube research.²⁶¹ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.²⁶²

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.²⁶³ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Ifosfamide

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.²⁶⁵ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.²⁶⁶ Vitamin C appears to increase the effectiveness of chemotherapy in animals²⁶⁷ and with human breast cancer cells in test tube research.²⁶⁸ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.²⁶⁹

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.²⁷⁰ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Irinotecan

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.²⁷¹ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.²⁷² Vitamin C appears to increase the effectiveness of chemotherapy in animals²⁷³ and with human breast cancer cells in test tube research.²⁷⁴ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.²⁷⁵

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.²⁷⁶ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Lomustine

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.²⁷⁸ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.²⁷⁹ Vitamin C appears to increase the effectiveness of chemotherapy in animals²⁸⁰ and with human breast cancer cells in test tube research.²⁸¹ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.²⁸²

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.²⁸³ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Mechlorethamine

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.²⁸⁴ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.²⁸⁵ Vitamin C appears to increase the effectiveness of chemotherapy in animals²⁸⁶ and with human breast cancer cells in test tube research.²⁸⁷ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.²⁸⁸

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.²⁸⁹ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Melphalan

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.²⁹⁰ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.²⁹¹ Vitamin C appears to increase the effectiveness of chemotherapy in animals²⁹² and with human breast cancer cells in test tube research.²⁹³ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.²⁹⁴

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.²⁹⁵ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.
Mercaptopurine

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.²⁹⁶ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.²⁹⁷ Vitamin C appears to increase the effectiveness of chemotherapy in animals²⁹⁸ and with human breast cancer cells in test tube research.²⁹⁹ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.³⁰⁰

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.³⁰¹ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Polifeprosan 20 with Carmustine

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.³¹² However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.³¹³ Vitamin C appears to increase the effectiveness of chemotherapy in animals³¹⁴ and with human breast cancer cells in test tube research.³¹⁵ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.³¹⁶

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.³¹⁷ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Prednisolone

In some people, treatment with corticosteroids can impair wound healing . In one study, topical or internal vitamin A improved wound healing in eight of ten patients on corticosteroid therapy.³¹⁸ In theory, vitamin A might also reverse some of the beneficial effects of corticosteroids, but this idea has not been investigated and no reports exist of such an interaction in people taking both vitamin A and corticosteroids. People using oral corticosteroids should consult with a doctor to determine whether improved wound healing might outweigh the theoretical risk associated with concomitant vitamin A use.

Although blood levels of vitamin A appear to increase during dexamethasone therapy³¹⁹—most likely due to mobilization of the vitamin from its stores in the liver evidence from animal studies has also indicated that corticosteroids can deplete vitamin A from tissues.³²⁰
Thioguanine

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.³²¹ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.³²² Vitamin C appears to increase the effectiveness of chemotherapy in animals³²³ and with human breast cancer cells in test tube research.³²⁴ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.³²⁵

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.³²⁶ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Thiotepa

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.³²⁸ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.³²⁹ Vitamin C appears to increase the effectiveness of chemotherapy in animals³³⁰ and with human breast cancer cells in test tube research.³³¹ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.³³²

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.³³³ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Uracil Mustard

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.³³⁵ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.³³⁶ Vitamin C appears to increase the effectiveness of chemotherapy in animals³³⁷ and with human breast cancer cells in test tube research.³³⁸ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.³³⁹

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.³⁴⁰ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Vincristine

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.³⁴² However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.³⁴³ Vitamin C appears to increase the effectiveness of chemotherapy in animals³⁴⁴ and with human breast cancer cells in test tube research.³⁴⁵ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.³⁴⁶

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.³⁴⁷ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Support Medicine

Docetaxel

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.²³⁸ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.²³⁹ Vitamin C appears to increase the effectiveness of chemotherapy in animals²⁴⁰ and with human breast cancer cells in test tube research.²⁴¹ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.²⁴²

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but it clearly shows that antioxidants need not be avoided for fear that the actions of chemotherapy are interfered with.²⁴³ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

A new formulation of selenium (Seleno-Kappacarrageenan) was found to reduce kidney damage and white blood cell–lowering effects of cisplatin in one human study. However, the level used in this study (4,000 mcg per day) is potentially toxic and should only be used under the supervision of a doctor.²⁴⁴

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Reduces Effectiveness

none

Potential Negative Interaction

Atorvastatin

A study of 37 people with high cholesterol treated with diet and HMG-CoA reductase inhibitors found blood vitamin A levels increased over two years of therapy.³⁴⁹ Until more is known, people taking HMG-CoA reductase inhibitors, including atorvastatin, should have blood levels of vitamin A monitored if they intend to supplement vitamin A.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Isotretinoin

Although little is known about how isotretinoin interacts with real vitamin A, the two are structurally similar and have similar toxicities. Therefore, people taking isotretinoin should avoid vitamin A supplements at levels higher than typically found in a multivitamin (10,000 IU per day).
Minocycline

A 16-year-old girl developed headaches and double vision following treatment for acne with vitamin A and minocycline. These side effects disappeared once the compounds were discontinued.³⁵⁰ More research is needed to determine whether the symptoms could have been caused by an interaction between vitamin A and the drug.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Tretinoin

Large amounts of vitamin A can cause side effects, and oral tretinoin can cause similar side effects. Combining vitamin A with oral tretinoin is likely to increase the risk of side effects. People taking oral tretinoin should probably not take more than 10,000 IU of supplemental vitamin A per day.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Explanation Required

Busulfan

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.³⁵¹ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.
Capecitabine

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.³⁵⁸ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Carboplatin

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.³⁵⁹ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.
Carmustine

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.³⁶⁰ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Chlorambucil

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.³⁶¹ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.
Cisplatin

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.³⁶² Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.³⁶³ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.³⁶⁴ Vitamin C appears to increase the effectiveness of chemotherapy in animals³⁶⁵ and with human breast cancer cells in test tube research.³⁶⁶ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.³⁶⁷

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.³⁶⁸ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Cladribine

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.³⁶⁹ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Cortisone

In some people, treatment with corticosteroids can impair wound healing . In one study, topical or internal vitamin A improved wound healing in eight of ten patients on corticosteroid therapy.³⁷⁰ In theory, vitamin A might also reverse some of the beneficial effects of corticosteroids, but this idea has not been investigated and no reports exist of such an interaction in people taking both vitamin A and corticosteroids. People using oral corticosteroids should consult with a doctor to determine whether improved wound healing might outweigh the theoretical risk associated with concomitant vitamin A use.

Although blood levels of vitamin A appear to increase during dexamethasone therapy³⁷¹—most likely due to mobilization of the vitamin from its stores in the liver—evidence from animal studies has also indicated that corticosteroids can deplete vitamin A from tissues.³⁷²

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Cyclophosphamide

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.³⁷³ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Cytarabine

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.³⁷⁵ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.³⁷⁶ Vitamin C appears to increase the effectiveness of chemotherapy in animals³⁷⁷ and with human breast cancer cells in test tube research.³⁷⁸ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.³⁷⁹

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.³⁸⁰ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Desogestrel-Ethinyl Estradiol

A review of literature suggests that women who use OCs may experience decreased vitamin B1 , B2 , B3 , B12 , C , and zinc levels.³⁸¹ ^{, 382} ^{, 383} OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A .³⁸⁴ ^{, 385} ^{, 386} OCs may interfere with manganese absorption.³⁸⁷ The clinical importance of these actions remains unclear.
Dexamethasone

In some people, treatment with corticosteroids can impair wound healing . In one study, topical or internal vitamin A improved wound healing in eight of ten patients on corticosteroid therapy.³⁸⁸ In theory, vitamin A might also reverse some of the beneficial effects of corticosteroids, but this idea has not been investigated and no reports exist of such an interaction in people taking both vitamin A and corticosteroids. People using oral corticosteroids should consult with a doctor to determine whether improved wound healing might outweigh the theoretical risk associated with concomitant vitamin A use.

Although blood levels of vitamin A appear to increase during dexamethasone therapy³⁸⁹—most likely due to mobilization of the vitamin from its stores in the liver—evidence from animal studies has also indicated that corticosteroids can deplete vitamin A from tissues.³⁹⁰

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Docetaxel

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.³⁹¹ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Erlotinib

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.³⁹² Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Ethinyl Estradiol and Levonorgestrel

A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1 , B2 , B3 , B12 , C , and zinc levels.³⁹³ ^{, 394} ^{, 395} Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A .³⁹⁶ ^{, 397} ^{, 398} Oral contraceptives may interfere with manganese absorption.³⁹⁹ The clinical importance of these actions remains unclear.
Ethinyl Estradiol and Norethindrone

A review of literature suggests that women who use OCs may experience decreased vitamin B1 , B2 , B3 , B12 , C , and zinc levels.⁴⁰⁰ ^{, 401} ^{, 402} OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A .⁴⁰³ ^{, 404} ^{, 405} OCs may interfere with manganese absorption.⁴⁰⁶ The clinical importance of these actions remains unclear.
Ethinyl Estradiol and Norgestimate
Ethinyl Estradiol and Norgestrel

A review of literature suggests that women who use OCs may experience decreased vitamin B1 , B2 , B3 , B12 , C , and zinc levels.⁴⁰⁷ ^{, 408} ^{, 409} OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A .⁴¹⁰ ^{, 411} ^{, 412} OCs may interfere with manganese absorption.⁴¹³ The clinical importance of these actions remains unclear.
Etoposide

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.⁴¹⁵ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.⁴¹⁶ Vitamin C appears to increase the effectiveness of chemotherapy in animals⁴¹⁷ and with human breast cancer cells in test tube research.⁴¹⁸ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.⁴¹⁹

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.⁴²⁰ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Floxuridine

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.⁴²¹ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Fludarabine

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.⁴²² Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Fluorouracil

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.⁴²⁴ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.⁴²⁵ Vitamin C appears to increase the effectiveness of chemotherapy in animals⁴²⁶ and with human breast cancer cells in test tube research.⁴²⁷ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.⁴²⁸

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but the article strongly suggests that antioxidants need not be avoided for fear that the actions of chemotherapy would be interfered with.⁴²⁹

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Fluvastatin

A study of 37 people with high cholesterol treated with diet and HMG-CoA reductase inhibitors found blood vitamin A levels increased during two years of therapy.⁴³⁰ Until more is known, people taking HMG-CoA reductase inhibitors, including fluvastatin, should have blood levels of vitamin A monitored if they intend to supplement vitamin A.
Hydroxyurea

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.⁴³² However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.⁴³³ Vitamin C appears to increase the effectiveness of chemotherapy in animals⁴³⁴ and with human breast cancer cells in test tube research.⁴³⁵ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.⁴³⁶

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.⁴³⁷ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Ifosfamide

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.⁴³⁸ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.
Irinotecan

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.⁴³⁹ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Levonorgestrel

A review of literature suggests that women who use OCs may experience decreased vitamin B1 , B2 , B3 , B12 , C , and zinc levels.⁴⁴⁰ ^{, 441} ^{, 442} OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A .⁴⁴³ ^{, 444} ^{, 445} OCs may interfere with manganese absorption.⁴⁴⁶ The clinical importance of these actions remains unclear.
Levonorgestrel-Ethinyl Estrad

A review of literature suggests that women who use OCs may experience decreased vitamin B1 , B2 , B3 , B12 , C , and zinc levels.⁴⁴⁷ ^{, 448} ^{, 449} OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A .⁴⁵⁰ ^{, 451} ^{, 452} OCs may interfere with manganese absorption.⁴⁵³ The clinical importance of these actions remains unclear.
Lomustine

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.⁴⁵⁴ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.
Lovastatin

A study of 37 people with high cholesterol treated with diet and HMG-CoA reductase inhibitors found serum vitamin A levels increased over two years of therapy.⁴⁵⁵ It remains unclear whether this moderate increase should suggest that people taking lovastatin have a particular need to restrict vitamin A supplementation.
Mechlorethamine

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.⁴⁵⁶ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.
Medroxyprogesterone

In a one-year study of predominantly malnourished women in India and Thailand, medroxyprogesterone used for contraception was associated with increased blood levels of vitamin A and folic acid.⁴⁵⁷ The clinical meaning of these changes remains unclear.
Melphalan

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.⁴⁵⁸ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.
Mercaptopurine

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.⁴⁵⁹ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Mestranol and Norethindrone

A review of literature suggests that women who use OCs may experience decreased vitamin B1 , B2 , B3 , B12 , C , and zinc levels.⁴⁶⁰ ^{, 461} ^{, 462} OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A .⁴⁶³ ^{, 464} ^{, 465} OCs may interfere with manganese absorption.⁴⁶⁶ The clinical importance of these actions remains unclear.
Methylprednisolone

In some people, treatment with corticosteroids can impair wound healing . In one study, topical or internal vitamin A improved wound healing in eight of ten patients on corticosteroid therapy.⁴⁶⁷ In theory, vitamin A might also reverse some of the beneficial effects of corticosteroids, but this idea has not been investigated and no reports exist of such an interaction in people taking both vitamin A and corticosteroids. People using oral corticosteroids should consult with a doctor to determine whether improved wound healing might outweigh the theoretical risk associated with concomitant vitamin A use.

Although blood levels of vitamin A appear to increase during dexamethasone therapy⁴⁶⁸—most likely due to mobilization of the vitamin from its stores in the liver—evidence from animal studies has also indicated that corticosteroids can deplete vitamin A from tissues.⁴⁶⁹

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Norgestimate-Ethinyl Estradiol

A review of literature suggests that women who use OCs may experience decreased vitamin B1 , B2 , B3 , B12 , C , and zinc levels.⁴⁷⁰ ^{, 471} ^{, 472} OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A .⁴⁷³ ^{, 474} ^{, 475} OCs may interfere with manganese absorption.⁴⁷⁶ The clinical importance of these actions remains unclear.
Paclitaxel

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.⁴⁷⁷ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.⁴⁷⁸ Vitamin C appears to increase the effectiveness of chemotherapy in animals⁴⁷⁹ and with human breast cancer cells in test tube research.⁴⁸⁰ In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.⁴⁸¹

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but the article strongly suggests that antioxidants need not be avoided for fear that the actions of chemotherapy would be interfered with.⁴⁸²

A new formulation of selenium (Seleno-Kappacarrageenan) was found to reduce kidney damage and white blood cell–lowering effects of cisplatin in one human study. However, the level used in this study (4,000 mcg per day) is potentially toxic and should only be used under the supervision of a doctor.⁴⁸³

Glutathione , the main antioxidant found within cells, is frequently depleted in individuals on chemotherapy and/or radiation. Preliminary studies have found that intravenously injected glutathione may decrease some of the adverse effects of chemotherapy and radiation, such as diarrhea .⁴⁸⁴

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Polifeprosan 20 with Carmustine

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.⁴⁸⁵ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.
Pravastatin

A study of 37 people with high cholesterol treated with diet and HMG-CoA reductase inhibitors found serum vitamin A levels increased over two years of therapy.⁴⁸⁶ It remains unclear whether this moderate increase suggests that people taking lovastatin have a particular need to restrict vitamin A supplementation.
Prednisolone

In some people, treatment with corticosteroids can impair wound healing . In one study, topical or internal vitamin A improved wound healing in eight of ten patients on corticosteroid therapy.⁴⁸⁷ In theory, vitamin A might also reverse some of the beneficial effects of corticosteroids, but this idea has not been investigated and no reports exist of such an interaction in people taking both vitamin A and corticosteroids. People using oral corticosteroids should consult with a doctor to determine whether improved wound healing might outweigh the theoretical risk associated with concomitant vitamin A use.

Although blood levels of vitamin A appear to increase during dexamethasone therapy⁴⁸⁸—most likely due to mobilization of the vitamin from its stores in the liver evidence from animal studies has also indicated that corticosteroids can deplete vitamin A from tissues.⁴⁸⁹

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Prednisone

In some people, treatment with corticosteroids can impair wound healing . In one study, topical or internal vitamin A improved wound healing in eight of ten patients on corticosteroid therapy.⁴⁹⁰ In theory, vitamin A might also reverse some of the beneficial effects of corticosteroids, but this idea has not been investigated and no reports exist of such an interaction in people taking both vitamin A and corticosteroids. People using oral corticosteroids should consult with a doctor to determine whether improved wound healing might outweigh the theoretical risk associated with concomitant vitamin A use.

Although blood levels of vitamin A appear to increase during dexamethasone therapy⁴⁹¹—most likely due to mobilization of the vitamin from its stores in the liver—evidence from animal studies has also indicated that corticosteroids can deplete vitamin A from tissues.⁴⁹²

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Primidone

Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.⁴⁹³ Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Simvastatin

A study of 37 people with high cholesterol treated with diet and HMG-CoA reductase inhibitors found blood vitamin A levels increased over two years of therapy.⁴⁹⁴ Until more is known, people taking HMG-CoA reductase inhibitors, including simvastatin, should have blood levels of vitamin A monitored if they intend to supplement vitamin A.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Thioguanine

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.⁴⁹⁵ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Thiotepa

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.⁴⁹⁶ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.
Uracil Mustard

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.⁴⁹⁷ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.
Vinblastine

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.⁴⁹⁹ However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.⁵⁰⁰ Vitamin C appears to increase the effectiveness of chemotherapy in animals⁵⁰¹ and with human breast cancer cells in test tube research.⁵⁰² In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.⁵⁰³

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.⁵⁰⁴ Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Vincristine

A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.⁵⁰⁵ Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a supplement with your doctor or pharmacist.

Side Effects

Since a 1995 report from the New England Journal of Medicine, ⁵⁰⁶ women who are or could become pregnant have been told by doctors to take less than 10,000 IU (3,000 mcg) per day of vitamin A to avoid the risk of birth defect . A recent report studied several hundred women exposed to 10,000–300,000 IU (median exposure of 50,000 IU) per day.⁵⁰⁷ Three major malformations occurred in this study, but all could have happened in the absence of vitamin A supplementation. Surprisingly, no congenital malformations happened in any of the 120 infants exposed to maternal intakes of vitamin A that exceeded 50,000 IU per day. In fact, the high-exposure group had a 50% decreased risk for malformations compared with infants not exposed to vitamin A. The authors noted that some previous studies found no link between vitamin A and birth defects, and argued the studies that did find such a link suffered from various weaknesses. A closer look at the recent study reveals a 32% higher than expected risk of birth defects in infants exposed to 10,000–40,000 IU of vitamin A per day, but paradoxically a 37% decreased risk for those exposed to even higher levels. This suggests that both “higher” and “lower” risks may have been due to chance.

Excessive dietary intake of vitamin A has been associated with birth defects in humans in fewer than 20 reported cases over the past 30 years.⁵⁰⁸ ^{, 509} Presently, the level at which vitamin A supplementation may cause birth defects is not known, though combined human and animal data suggest that 30,000 IU per day should be considered safe.⁵¹⁰ Women who are or who could become pregnant should consult with a doctor before supplementing with more than 10,000 IU per day.

Vitamin A supplements can both help and hurt children. Many people have heard that vitamin A supplements support immune function and prevent infections . This is true under some circumstances. However, vitamin A can also increase the risk of infections, according to the findings of a double-blind trial.⁵¹¹ In a study of African children between six months and five years old, a 44% reduction in the risk of severe diarrhea was seen in those children given four 100,000–200,000 IU applications of vitamin A (the lower amount for those less than a year old) during an eight-month period. On further investigation, the researchers discovered that the reduction in diarrhea occurred only in children who were very malnourished. For children who were not starving, vitamin A supplementation actually increased the risk of diarrhea compared with the placebo group. The vitamin A-supplemented children also had a 67% increased risk of coughing and rapid breathing, signs of further lung infection, although this problem did not appear in children infected with AIDS. These findings should be of concern to American parents, whose children are not usually infected with AIDS or severely malnourished. Such relatively healthy children fared poorly in the African trial in terms of both the risk of diarrhea and the risk of continued lung problems. Vitamin A provided no benefit to the well-nourished kids. Therefore, it makes sense to not give vitamin A supplements to children unless there is a special reason to do so, such as the presence of a condition causing malabsorption (e.g., celiac disease ).

In a study of people with retinitis pigmentosa (a degenerative condition of the eye), participants received 15,000 IU of vitamin A per day for 12 years with no signs of adverse effects or toxicity.⁵¹² For other adults, intake above 25,000 IU (7,500 mcg) per day can—in rare cases—cause headaches, dry skin, hair loss, fatigue, bone problems, and liver damage.⁵¹³ At higher levels (for example 100,000 IU per day) these problems become more common.

A controlled clinical trial showed that people who took 25,000 IU of vitamin A per day for a median of 3.8 years had an 11% increase in triglycerides , a 3% increase in total cholesterol and a 1% decrease in HDL cholesterol compared to those who did not take vitamin A.⁵¹⁴ Although the significance of these findings is not clear, people at risk for cardiovascular disease should use caution when considering long-term vitamin A supplementation.

One study found that increasing the intake of vitamin A in the diet was associated with bone loss and risk of hip fracture, possibly due to a vitamin A-induced stimulation of cells that break down bone.⁵¹⁵ In this study, a vitamin A intake greater than 5,000 IU per day, when compared to a lower intake, was associated with a reduction in bone mineral density that approximately doubles the risk of hip fracture. Beta-carotene (which can be used by the body to make vitamin A) has not been linked to reduced bone mass. Until more is known, people concerned about osteoporosis may consider taking beta-carotene supplements rather than supplementing with vitamin A.

Data from test tube, animal, and human studies show that excessive vitamin A intake can accelerate bone loss and inhibit formation of new bone, increasing the risk of osteoporosis.⁵¹⁶ In humans, small studies have found these effects at about 85,000–125,000 IU per day. ⁵¹⁷ ^{, 518}

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228. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

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238. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

239. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

240. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

241. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

242. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

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246. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

247. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

248. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

249. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

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251. Nau H, Tzimas G, Mondry M, et al. Antiepileptic drugs alter endogenous retinoid concentrations: a possible mechanism of teratogensis of anticonvulsant therapy. Life Sci 1995;57:53–60.

252. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

253. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

254. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

255. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

256. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

257. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

258. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

259. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

260. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

261. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

262. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

263. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

264. Nau H, Tzimas G, Mondry M, et al. Antiepileptic drugs alter endogenous retinoid concentrations: a possible mechanism of teratogensis of anticonvulsant therapy. Life Sci 1995;57:53–60.

265. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

266. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

267. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

268. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

269. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

270. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

271. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

272. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

273. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

274. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

275. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

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277. Nau H, Tzimas G, Mondry M, et al. Antiepileptic drugs alter endogenous retinoid concentrations: a possible mechanism of teratogensis of anticonvulsant therapy. Life Sci 1995;57:53–60.

278. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

279. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

280. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

281. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

282. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

283. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

284. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

285. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

286. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

287. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

288. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

289. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

290. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

291. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

292. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

293. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

294. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

295. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

296. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

297. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

298. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

299. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

300. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

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311. Nau H, Tzimas G, Mondry M, et al. Antiepileptic drugs alter endogenous retinoid concentrations: a possible mechanism of teratogensis of anticonvulsant therapy. Life Sci 1995;57:53–60.

312. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

313. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

314. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

315. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

316. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

317. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

318. Hunt TK, Ehrlich HP, Garcia JA, Dunphy JE. Effect of vitamin A on reversing the inhibitory effect of cortisone on healing of open wounds in animals and man. Ann Surg 1969;170:633–40.

319. Shenai JP, Mellen BG, Chytil F. Vitamin A status and postnatal dexamethasone treatment in bronchopulmonary dysplasia. Pediatrics 2000;106:547–53.

320. Georgieff MK, Radmer WJ, Sowell AL. The effect of glucocorticosteroids on serum, liver, and lung vitamin A and retinyl ester concentrations. J Pediatr Gastroenterol Nutr 1991;13:376–82.

321. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

322. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

323. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

324. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

325. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

326. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

327. Curtis JL. Effects of medication on plasma vitamin A concentrations. Clin Chem 1976;22:695.

328. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

329. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

330. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

331. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

332. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

333. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

334. Nau H, Tzimas G, Mondry M, et al. Antiepileptic drugs alter endogenous retinoid concentrations: a possible mechanism of teratogensis of anticonvulsant therapy. Life Sci 1995;57:53–60.

335. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

336. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

337. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

338. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

339. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

340. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

341. Nau H, Tzimas G, Mondry M, et al. Antiepileptic drugs alter endogenous retinoid concentrations: a possible mechanism of teratogensis of anticonvulsant therapy. Life Sci 1995;57:53–60.

342. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

343. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

344. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

345. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

346. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

347. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

348. Nau H, Tzimas G, Mondry M, et al. Antiepileptic drugs alter endogenous retinoid concentrations: a possible mechanism of teratogensis of anticonvulsant therapy. Life Sci 1995;57:53–60.

349. Muggeo M, Zenti MG, Travia D, et al. Serum retinol levels throughout 2 years of cholesterol-lowering therapy. Metabolism 1995;44:398–403.

350. Moskowitz Y, Leibowitz E, Ronen M, Aviel E. Pseudotumor cerebri induced by vitamin A combined with minocycline. Ann Ophthalmol 1993;25:306–8.

351. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

352. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

353. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

354. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

355. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

356. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

357. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

358. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

359. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

360. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

361. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

362. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

363. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

364. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

365. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

366. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

367. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

368. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

369. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

370. Hunt TK, Ehrlich HP, Garcia JA, Dunphy JE. Effect of vitamin A on reversing the inhibitory effect of cortisone on healing of open wounds in animals and man. Ann Surg1969;170:633–40.

371. Shenai JP, Mellen BG, Chytil F. Vitamin A status and postnatal dexamethasone treatment in bronchopulmonary dysplasia. Pediatrics 2000;106:547–53.

372. Georgieff MK, Radmer WJ, Sowell AL. The effect of glucocorticosteroids on serum, liver, and lung vitamin A and retinyl ester concentrations. J Pediatr Gastroenterol Nutr 1991;13:376–82.

373. Israel L, Hajji O, Grefft-Alami A, et al. Agumentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

374. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

375. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

376. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

377. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

378. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

379. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

380. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

381. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].

382. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.

383. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197–8.

384. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].

385. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.

386. Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr 1998;52:711–5.

387. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.

388. Hunt TK, Ehrlich HP, Garcia JA, Dunphy JE. Effect of vitamin A on reversing the inhibitory effect of cortisone on healing of open wounds in animals and man. Ann Surg 1969;170:633–40.

389. Shenai JP, Mellen BG, Chytil F. Vitamin A status and postnatal dexamethasone treatment in bronchopulmonary dysplasia. Pediatrics 2000;106:547–53.

390. Georgieff MK, Radmer WJ, Sowell AL. The effect of glucocorticosteroids on serum, liver, and lung vitamin A and retinyl ester concentrations. J Pediatr Gastroenterol Nutr 1991;13:376–82.

391. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

392. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

393. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].

394. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.

395. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197–8.

396. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].

397. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.

398. Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr 1998;52:711–5.

399. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.

400. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].

401. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.

402. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197–8.

403. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].

404. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.

405. Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr 1998;52:711–5.

406. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.

407. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].

408. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.

409. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197–8.

410. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].

411. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.

412. Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr 1998;52:711–5.

413. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.

414. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

415. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

416. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

417. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

418. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

419. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

420. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

421. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

422. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

423. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

424. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

425. Sacks PG, Harris D, Chou TC. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

426. Taper HS, et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

427. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

428. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

429. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

430. Muggeo M, Zenti MG, Travia D, et al. Serum retinol levels throughout 2 years of cholesterol-lowering therapy. Metabolism 1995;44:398–403.

431. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

432. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

433. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

434. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

435. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

436. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

437. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

438. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

439. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

440. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].

441. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.

442. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197–8.

443. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].

444. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.

445. Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr 1998;52:711–5.

446. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.

447. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].

448. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.

449. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197–8.

450. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].

451. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.

452. Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr 1998;52:711–5.

453. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.

454. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

455. Muggeo M, Zenti MG, Travia D, et al. Serum retinol levels throughout two years of cholesterol-lowering therapy. Metabolism 1995;44:398–403.

456. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

457. Joshi UM, Virkar KD, Amatayakul K, et al. Impact of hormonal contraceptives vis-a-vis non-hormonal factors on the vitamin status of malnourished women in India and Thailand. World Health Organization: Special Programme of Research, Development and Research Training in Human Reproduction. Task Force on Oral Contraceptives. Hum Nutr Clin Nutr 1986;40:205–20.

458. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

459. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

460. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].

461. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.

462. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197–8.

463. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].

464. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.

465. Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr 1998;52:711–5.

466. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.

467. Hunt TK, Ehrlich HP, Garcia JA, Dunphy JE. Effect of vitamin A on reversing the inhibitory effect of cortisone on healing of open wounds in animals and man. Ann Surg 1969;170:633–40.

468. Shenai JP, Mellen BG, Chytil F. Vitamin A status and postnatal dexamethasone treatment in bronchopulmonary dysplasia. Pediatrics 2000;106:547–53.

469. Georgieff MK, Radmer WJ, Sowell AL. The effect of glucocorticosteroids on serum, liver, and lung vitamin A and retinyl ester concentrations. J Pediatr Gastroenterol Nutr 1991;13:376–82.

470. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].

471. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.

472. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197–8.

473. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].

474. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.

475. Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr 1998;52:711–5.

476. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.

477. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

478. Sacks PG, Harris D, Chou TC. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

479. Taper HS, de Gerlache J, Lans M, Roberfroid M. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

480. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

481. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

482. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

483. Hu YJ, Chen Y, Zhang YQ, et al. The protective role of selenium on the toxicity of cisplatin-contained chemotherapy regimen in cancer patients. Biol Trace Elem Res 1997;56:331–41.

484. De Maria D, Falchi AM, Venturino P. Adjuvant radiotherapy of the pelvis with or without reduced glutathione: a randomized trial in patients operated on for endometrial cancer. Tumori 1992;78:374–6.

485. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

486. Muggeo M, Zenti MG, Travia D, et al. Serum retinol levels throughout two years of cholesterol-lowering therapy. Metabolism 1995;44:398–403.

487. Hunt TK, Ehrlich HP, Garcia JA, Dunphy JE. Effect of vitamin A on reversing the inhibitory effect of cortisone on healing of open wounds in animals and man. Ann Surg 1969;170:633–40.

488. Shenai JP, Mellen BG, Chytil F. Vitamin A status and postnatal dexamethasone treatment in bronchopulmonary dysplasia. Pediatrics 2000;106:547–53.

489. Georgieff MK, Radmer WJ, Sowell AL. The effect of glucocorticosteroids on serum, liver, and lung vitamin A and retinyl ester concentrations. J Pediatr Gastroenterol Nutr 1991;13:376–82.

490. Hunt TK, Ehrlich HP, Garcia JA, Dunphy JE. Effect of vitamin A on reversing the inhibitory effect of cortisone on healing of open wounds in animals and man. Ann Surg 1969;170:633–40.

491. Shenai JP, Mellen BG, Chytil F. Vitamin A status and postnatal dexamethasone treatment in bronchopulmonary dysplasia. Pediatrics 2000;106:547–53.

492. Georgieff MK, Radmer WJ, Sowell AL. The effect of glucocorticosteroids on serum, liver, and lung vitamin A and retinyl ester concentrations. J Pediatr Gastroenterol Nutr 1991;13:376–82.

493. Nau H, Tzimas G, Mondry M, et al. Antiepileptic drugs alter endogenous retinoid concentrations: a possible mechanism of teratogensis of anticonvulsant therapy. Life Sci 1995;57:53–60.

494. Muggeo M, Zenti MG, Travia D, et al. Serum retinol levels throughout 2 years of cholesterol-lowering therapy. Metabolism 1995;44:398–403.

495. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

496. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

497. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

498. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

499. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823–32.

500. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409–15.

501. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575–9.

502. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103–19.

503. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353–9.

504. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209–40 [review].

505. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551–4.

506. Rothman KJ, Moore LL, Singer MR, et al. Teratogenicity of high vitamin A intake. N Engl J Med 1995;333:1369–73.

507. Mastroiacovo P, Mazzone T, Addis A, et al. High vitamin A intake in early pregnancy and major malformations: a multicenter prospective controlled study. Teratology 1999;59:7–11.

508. Biesalski HK. Comparative assessment of the toxicology of vitamin A and retinoids in man. Toxicology 1989;57:117–61.

509. Azais-Braesco V, Pascal G. Vitamin A in pregnancy: requirements and safety limits. Am J Clin Nutr 2000;71(5 Suppl):1325S–33S [review].

510. Wiegand UW, Hartmann S, Hummler H. Safety of vitamin A: recent results. Int J Vitam Nutr Res 1998;68:411–6 [review].

511. Fawzi WW, Mbise R, Spiegelman D, et al. Vitamin A supplements and diarrheal and respiratory tract infections among children in Dar es Salaam, Tanzania. J Pediatr 2000;137:660–7.

512. Sibulesky L, Hayes KC, Pronczuk A, et al. Safety of <7500 RE (<25000 IU) vitamin A daily in adults with retinitis pigmentosa. Am J Clin Nutr 1999;69:656–63.

513. Bendich A, Langseth L. Safety of vitamin A. Am J Clin Nutr 1989;49:358–71.

514. Cartmel B, Moon TE, Levine N. Effects of long-term intake of retinol on selected clinical and laboratory indexes. Am J Clin Nutr 1999;69:937–43.

515. Melhus H, Michaelsson K, Kindmark A, et al. Excessive dietary intake of vitamin A is associated with reduced bone mineral density and increased risk for hip fracture. Ann Int Med 1998;129:770–8.

516. Binkley N, Krueger D. Hypervitaminosis A and bone. Nutr Rev 2000;58:138–44 [review].

517. Frame B, Jackson CE, Reynolds WA, Umphrey JE. Hypercalcemia and skeletal effects in chronic hypervitaminosis A. Ann Intern Med 1974;80:44–8.

518. Patel P, Hanning RM, Atkinson SA, et al. Intoxication from vitamin A in an asthmatic child. CMAJ 1988;139:755–6.

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Last Review: 11-07-2012

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The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2013.

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Topic Contents

Vitamin A

Uses

This supplement has been used in connection with the following health conditions:

How It Works

How to Use It

Where to Find It

Possible Deficiencies

Interactions

Interactions with Supplements, Foods, & Other Compounds

Interactions with Medicines

Replenish Depleted Nutrients

Reduce Side Effects

Support Medicine

Reduces Effectiveness

Potential Negative Interaction

Explanation Required

Side Effects

Side Effects

Related Information

References