Skip navigation
A service of the U.S. National Library of Medicine
From the National Institutes of HealthNational Institutes of Health

Vitamin A


What is it?

Vitamin A is a vitamin. It can be found in many fruits, vegetables, eggs, whole milk, butter, fortified margarine, meat, and oily saltwater fish. It can also be made in a laboratory.

Vitamin A is used for treating vitamin A deficiency. It is also used to reduce complications of diseases such as malaria, HIV, measles, and diarrhea in children with vitamin A deficiency.

Women use vitamin A for heavy menstrual periods, premenstrual syndrome (PMS), vaginal infections, yeast infections, “lumpy breasts” (fibrocystic breast disease), and to prevent breast cancer. Some women with HIV use vitamin A to decrease the risk of transmitting HIV to the baby during pregnancy, childbirth, or breast-feeding.

Men use vitamin A to raise their sperm count.

Some people use vitamin A for improving vision and treating eye disorders including age-related macular degeneration (AMD), glaucoma, and cataracts.

Vitamin A is also used for skin conditions including acne, eczema, psoriasis, cold sores, wounds, burns, sunburn, keratosis follicularis (Darier’s disease), ichthyosis (noninflammatory skin scaling), lichen planus pigmentosus, and pityriasis rubra pilaris.

It is also used for gastrointestinal ulcers, Crohn’s disease, gum disease, diabetes, Hurler syndrome (mucopolysaccharidosis), sinus infections, hayfever, and urinary tract infections (UTIs).

Vitamin A is also used for shigellosis, diseases of the nervous system, nose infections, loss of sense of smell, asthma, persistent headaches, kidney stones, overactive thyroid, iron-poor blood (anemia), deafness, ringing in the ears, and precancerous mouth sores (leukoplakia).

Other uses include preventing and treating cancer, protecting the heart and cardiovascular system, slowing the aging process, and boosting the immune system.

Vitamin A is applied to the skin to improve wound healing, reduce wrinkles, and to protect the skin against UV radiation.

How effective is it?

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.

The effectiveness ratings for VITAMIN A are as follows:

Effective for...

  • Treatment and prevention of vitamin A deficiency. Vitamin A deficiency can occur in people with protein deficiency, diabetes, over-active thyroid, fever, liver disease, cystic fibrosis, or an inherited disorder called abetalipoproteinemia.

Possibly effective for...

  • Preventing breast cancer. Women who have not passed menopause and who get high levels of vitamin A from their diet seem to be at lower risk of getting breast cancer than other women. It’s not known whether taking vitamin A supplements has the same benefit.
  • Reducing complications of diseases such as malaria, HIV, measles, and diarrhea in children with vitamin A deficiency.
  • Reducing problems during pregnancy and after giving birth in underfed (malnourished) women.
  • Prevention of cataracts.
  • Improving recovery from laser eye surgery when used in combination with vitamin E.

Possibly ineffective for...

  • Reducing fetal and early infant death in children born to women with nutrition problems.
  • Iron-poor blood (anemia).
  • Decreasing the risk of HIV transmission during pregnancy, delivery, and breast-feeding.
  • Reducing side effects of chemotherapy in children.

Likely ineffective for...

  • Reducing the risk of tumors in the head and neck.
  • Treating pneumonia in children living in poor countries.

Insufficient evidence to rate effectiveness for...

  • Lung cancer. Limited research suggests that taking vitamin A by mouth might improve survival and reduce the development of new tumors in people with lung cancer.
  • Ovarian cancer. Population research suggests that taking vitamin A doesn’t affect the risk of developing ovarian cancer.
  • Cervical cancer. Preliminary clinical research suggests that a specific form of vitamin A, 13-cis-retinoic acid, taken by mouth might improve precancerous changes in the cervix of women with human papillomavirus (HPV) infection.
  • Esophageal cancer. Taking vitamin A in combination with beta-carotene does not seem to prevent esophageal cancer.
  • Pancreatic cancer. Taking vitamin A in combination with beta-carotene does not seem to prevent pancreatic cancer.
  • Colorectal cancer. Taking vitamin A in combination with beta-carotene does not seem to prevent colorectal cancer.
  • Stomach cancer. Taking vitamin A in combination with beta-carotene does not seem to prevent stomach cancer.
  • Promoting good vision.
  • Age-related macular degeneration (AMD).
  • Glaucoma.
  • Preventing and speeding recovery from infections.
  • Improving immune function.
  • Wrinkled skin.
  • Wound healing.
  • Relieving hay fever symptoms.
  • Other conditions.
More evidence is needed to rate vitamin A for these uses.

How does it work?

Return to top
Vitamin A is required for the proper development and functioning of our eyes, skin, immune system, and many other parts of our bodies.

Are there safety concerns?

Return to top
Vitamin A is LIKELY SAFE for most people when taken by mouth in amounts less than 10,000 units per day.

Some scientific research suggests that higher doses might increase the risk of osteoporosis and hip fracture, particularly in older people. Adults who eat low-fat dairy products, which are fortified with vitamin A, and a lot of fruits and vegetables usually don’t need vitamin A supplements or multivitamins that contain vitamin A.

Long-term use of large amounts of vitamin A might cause serious side effects including fatigue, irritability, mental changes, anorexia, stomach discomfort, nausea, vomiting, mild fever, excessive sweating, and many other side effects. In women who have passed menopause, taking too much vitamin A can increase the risk of osteoporosis and hip fracture.

There is growing concern that taking high doses of antioxidant supplements such as vitamin A might do more harm than good. Some research shows that taking high doses of vitamin A supplements might increase the chance of death from all causes and possibly other serious side effects.

Vitamin A is likely safe for children when taken in the recommended amounts. When amounts greater than those recommended are taken, side effects can include irritability, sleepiness, vomiting, diarrhea, loss of consciousness, headache, vision problems, peeling skin, increased risk of pneumonia and diarrhea, and other problems. The maximum amounts of vitamin A that are safe for children are based on age:
  • Less than 2000 units/day in children up to 3 years old.
  • Less than 3000 units/day in children ages 4 to 8 years old.
  • Less than 5700 units/day in children ages 9 to 13 years old.
  • Less than 9300 units/day in children ages 14 to 18 years old.

Special precautions & warnings:

Pregnancy and breast-feeding: Vitamin A is LIKELY SAFE for pregnant or breast-feeding women when taken in recommended amounts of less than 10,000 units per day. Larger amounts are POSSIBLY UNSAFE. Vitamin A can cause birth defects. It’s especially important for pregnant women to monitor their intake of vitamin A from all sources during the first three months of pregnancy. Forms of vitamin A are found in several foods including animal products, primarily liver, some fortified breakfast cereals, and dietary supplements.

Excessive use of alcohol: Drinking alcohol may increase vitamin A’s potentially harmful effects on the liver.

A type of high cholesterol called "Type V hyperlipoproteinemia:" This condition might increase the chance of vitamin A poisoning. Don’t take vitamin A if you have this condition.

Liver disease: Too much vitamin A might make liver disease worse. Don’t take vitamin A if you have liver disease.

Are there interactions with medications?

Return to top

Major

Do not take this combination.

Medications for skin conditions (Retinoids)
Some medications for skin conditions have vitamin A effects. Taking vitamin A pills and these medications for skin conditions could cause too much vitamin A effects and side effects.

Moderate

Be cautious with this combination.

Antibiotics (Tetracycline antibiotics)
Vitamin A can interact with some antibiotics. Taking very large amounts of vitamin A along with some antibiotics can increase the chance of a serious side effect called intracranial hypertension. But taking normal doses of vitamin A along with tetracyclines doesn't seem to cause this problem. Do not take large amounts of vitamin A if you are taking antibiotics.

Some of these antibiotics include demeclocycline (Declomycin), minocycline (Minocin), and tetracycline (Achromycin).

Medications that can harm the liver (Hepatotoxic drugs)
Taking large amounts of vitamin A might harm the liver. Taking large amounts of vitamin A along with medications that might also harm the liver can increase the risk of liver damage. Do not take large amounts of vitamin A if you are taking a medication that can harm the liver.

Some medications that can harm the liver include acetaminophen (Tylenol and others), amiodarone (Cordarone), carbamazepine (Tegretol), isoniazid (INH), methotrexate (Rheumatrex), methyldopa (Aldomet), fluconazole (Diflucan), itraconazole (Sporanox), erythromycin (Erythrocin, Ilosone, others), phenytoin (Dilantin), lovastatin (Mevacor), pravastatin (Pravachol), simvastatin (Zocor), and many others.

Warfarin (Coumadin)
Warfarin (Coumadin) is used to slow blood clotting. Large amounts of vitamin A can also slow blood clotting. Taking vitamin A along with warfarin (Coumadin) can increase the chances of bruising and bleeding. Be sure to have your blood checked regularly. The dose of your warfarin (Coumadin) might need to be changed.

Are there interactions with herbs and supplements?

Return to top
Iron
Red blood cells need iron to make hemoglobin, the chemical that carries oxygen through the body. Taking vitamin A seems to improve hemoglobin levels in people who have low levels of iron and vitamin A.

Are there interactions with foods?

Return to top
Fatty foods
Eating fatty foods helps the body absorb vitamin A.

What dose is used?

Return to top
Adequate Intake (AI) levels of vitamin A for infants have been established: birth to 6 months, 400 mcg/day (1300 units); 7 to 12 months, 500 mcg/day (1700 units).

Recommended Dietary Allowance (RDA) levels for children and adults have been established: children 1 to 3 years, 300 mcg/day (1000 units); 4 to 8 years, 400 mcg/day (1300 units); 9 to 13 years, 600 mcg/day (2000 units); men 14 years and older, 900 mcg/day (3000 units); women 14 years and older, 700 mcg/day (2300 units); pregnancy 14 to 18 years, 750 mcg/day (2500 units); 19 years and older, 770 mcg/day (2600 units); lactation 14 to 18 years, 1200 mcg/day (4000 units); 19 years and older, 1300 mcg/day (4300 units). Tolerable Upper Intake Levels (UL) for vitamin A have also been established. The UL is the highest level of intake that is likely to pose no risk of harmful effects. The ULs for vitamin A are for preformed vitamin A (retinol) and do not include provitamin A carotenoids: infants and children from birth to 3 years, 600 mcg/day (2000 units); children 4 to 8 years, 900 mcg/day (3000 units); 9 to 13 years, 1700 mcg/day (6000 units); 14 to 18 years (including pregnancy and lactation), 2800 mcg/day (9000 units); adults age 19 and older (including pregnancy and lactation), 3000 mcg/day (10,000 units).

Vitamin A dosage is most commonly expressed in units, but dosage in micrograms is sometimes used.

Eating 5 servings of fruits and vegetables per day provides about 50% to 65% of the adult RDA for vitamin A.

Other names

Return to top
3-Dehydroretinol, 3-Déhydrorétinol, Acétate de Rétinol, Antixerophthalmic Vitamin, Axerophtholum, Dehydroretinol, Déhydrorétinol, Fat-Soluble Vitamin, Oleovitamin A, Palmitate de Rétinol, Retinoids, Rétinoïdes, Retinol, Rétinol, Retinol Acetate, Retinol Palmitate, Retinyl Acetate, Rétinyl Acétate, Retinyl Palmitate, Rétinyl Palmitate, Vitamin A Acetate, Vitamin A Palmitate, Vitamin A1, Vitamin A2, Vitamina A, Vitamine A, Vitamine A1, Vitamine A2, Vitamine Liposoluble, Vitaminum A.

Methodology

Return to top
To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.methodology (http://www.nlm.nih.gov/medlineplus/druginfo/natural/methodology.html).

References

Return to top
To see all references for the Vitamin A page, please go to http://www.nlm.nih.gov/medlineplus/druginfo/natural/964.html.

  1. Smedts HP, de Vries JH, Rakhshandehroo M, et al. High maternal vitamin E intake by diet or supplements is associated with congenital heart defects in the offspring. BJOG 2009;116:416-23.
  2. Bjelakovic G, Nikolova D, Gluud LL, et al. Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis. JAMA 2007;297:842-57.
  3. Anon. Dermatologists can help consumers find the best products to rejuvenate their skin. American Academy of Dermatology, 1999. Available at: http://www.aad.org/PressReleases/rejuvenate.html
  4. Bjelakovic G, Nikolova D, Simonetti RG, Gluud C. Antioxidant supplements for prevention of gastrointestinal cancers: a systematic review and meta-analysis. Lancet 2004;364:1219-28.
  5. Azais-Braesco V, Pascal G. Vitamin A in pregnancy: requirements and safety limits. Am J Clin Nutr 2000;71:1325S-33S.
  6. Sjostrom L, Rissanen A, Andersen T, et al. Randomised placebo-controlled trial of orlistat for weight loss and prevention of weight regain in obese patients. Lancet 1998;352:167-73.
  7. Davidson MH, Hauptman J, DiGirolamo M, et al. Weight control and risk factor reduction in obese subjects treated for 2 years with orlistat. JAMA 1999;281:235-42.
  8. Lipid Research Clinics Program. The Lipid Research Clinics' Coronary Primary Prevention Trial Results: 1. Reduction in incidence of coronary heart disease. JAMA 1984;251:351-64.
  9. Probstfield JL, Lin TL, Peters J, Hunninghake DB. Carotenoids and vitamin A: the effect of hypocholesterolemic agents on serum levels. Metabolism 1985;34:88-91.
  10. Glueck CJ, Tsang RC, Fallat RW, Scheel D. Plasma vitamin A and E levels in children with familial type II hyperlipoproteinemia during therapy with diet and cholestyramine resin. Pediatrics 1974;54:51-5.
  1. Schade RWB, van't Laar A, Majoor CLH, Jansen AP. A comparative study of the effects of cholestyramine and neomycin in the treatment of type II hyperlipoproteinemia. Acta Med Scand 1976;199:175-80.
  2. Barrowman JA, Broomhall J, Cannon AM, et al. Impairment of vitamin A absorption by neomycin. Clin Sci 1972;42:17P.
  3. Garrett-Laster M, Oaks L, Russell RM, Oaks E. A lowering effect of a pharmacological dose of vitamin E on serum vitamin A in normal adults. Nutr Res 1981;1:559-64.
  4. Jagadeesan V, Reddy V. Interrelationship between vitamin E and A: a clinical study. Clin Chim Acta 1978;90:71-4.
  5. Ayres S, Mihan R, Scribner MD. Synergism of vitamins A and E with dermatologic applications. Cutis 1979;23:600-3, 689-90.
  6. Willett WC, Stampfer MJ, Underwood BA, et al. Vitamins A, E and carotene: effects of supplementation on their plasma levels. Am J Clin Nutr 1983;38:559-66.
  7. Bendich A, Langseth L. Safety of vitamin A. Am J Clin Nutr 1989;49:358-71.
  8. Kusin JA, Reddy V, Sivakumar B. Vitamin E supplements and the absorption of a massive dose of vitamin A. Am J Clin Nutr 1974;27:774-6.
  9. Bauernfeind JC, Newmark H, Brin M. Vitamins A and E nutrition via intramuscular or oral route. Am J Clin Nutr 1974;27:234-53.
  10. DiPalma JR, Ritchie DM. Vitamin Toxicity. Annu Rev Pharmacol Toxicol 1977;17:133-48.
  11. Thorp VJ. Effect of oral contraceptive agents on vitamin and mineral requirements. J Am Diet Assoc 1980;76:581-4.
  12. Pearson MG, Littlewood SM, Bowden AN. Tetracycline and benign intracranial hypertension (letter). Br Med J 1981;282:568-9.
  13. Walters BN, Gubbay SS. Tetracycline and benign intracranial hypertension: report of five cases. Br Med J 1981;282:19-20.
  14. Hathcock JN, Hattan DG, Jenkins MY, et al. Evaluation of vitamin A toxicity. Am J Clin Nutr 1990;52:183-202.
  15. Ahmed F, Bamji MS, Iyengar L. Effect of oral contraceptive agents on vitamin nutrition status. Am J Clin Nutr 1975;28:606-15.
  16. Kokkonen J, Mottonen M, Karttunen TJ, Lanning M. Mucosal pathology of the upper gastrointestinal tract associated with intensive chemotherapy in children: vitamin A supplements do not prevent lesions. Pediatr Hematol Oncol 2002;19:181-92.
  17. Fawzi WW, Msamanga GI, Hunter D, et al. Randomized trial of vitamin supplements in relation to transmission of HIV-1 through breastfeeding and early child mortality. AIDS 2002;16:1935-44.
  18. French AL, Kirstein LM, Massad LS, et al. Association of vitamin A deficiency with cervical squamous intraepithelial lesions in human immunodeficiency virus-infected women. J Infect Dis 2000;182:1084-9.
  19. McDuffie JR, Calis KA, Booth SL, et al. Effects of orlistat on fat-soluble vitamins in obese adolescents. Pharmacotherapy 2002;22:814-22.
  20. Lynch SR. Interaction of iron with other nutrients. Nutr Rev 1997;55:102-10.
  21. Garcia-Casal MN, Layrisse M, Solano L, et al. Vitamin A and beta-carotene can improve nonheme iron absorption from rice, wheat and corn by humans. J Nutr 1998;128:646-50.
  22. Fishman SM, Christian P, West KP. The role of vitamins in the prevention and control of anaemia. Public Health Nutr 2000;3:125-50.
  23. Tyrer LB. Nutrition and the pill. J Reprod Med 1984;29:547-50.
  24. Mooij PN, Thomas CM, Doesburg WH, Eskes TK. Multivitamin supplementation in oral contraceptive users. Contraception 1991;44:277-88.
  25. Meyskens FL Jr, Graham V, Chvapil M, et al. A phase I trial of beta-all-trans-retinoic acid delivered via a collagen sponge and a cervical cap for mild or moderate intraepithelial cervical neoplasia. J Natl Cancer Inst 1983;71:921-5.
  26. Ahn WS, Lee JM, Namkoong SE, et al. Effect of retinoic acid on HPV titration and colposcopic changes in Korean patients with dysplasia of the uterine cervix. J Cell Biochem Suppl 1997;28-29:133-9.
  27. Ross AC. Addressing research questions with national survey data-the relation of vitamin A status to infection and inflammation. Am J Clin Nutr 2000;72:1069-70.
  28. Ballew C, Bowman BA, Russell RM, et al. Serum retinyl esters are not associated with biochemical markers of liver dysfunction in adult participants in the third National Health and Nutrition Examination Survey (NHANES III), 1988--1994. Am J Clin Nutr 2001;73:934-40.
  29. Schunemann HJ, Grant BJ, Freudenheim JL, et al. The relation of serum levels of antioxidant vitamins C and E, retinol and carotenoids with pulmonary function in the general population. Am J Respir Crit Care Med 2001;163:1246-55.
  30. Botterweck AA, van den Brandt PA, Goldbohm RA. Vitamins, carotenoids, dietary fiber, and the risk of gastric carcinoma: results from a prospective study after 6.3 years of follow-up. Cancer 2000;88:737-48.
  31. Fairfield KM, Hankinson SE, Rosner BA, et al. Risk of ovarian carcinoma and consumption of vitamins A, C, and E and specific carotenoids: a prospective analysis. Cancer 2001;92:2318-26.
  32. Johansson S, Lind PM, Hakansson H, et al. Subclinical hypervitaminosis A causes fragile bones in rats. Bone 2002;31:685-9.
  33. Lips P. Hypervitaminosis A and fractures. N Engl J Med 2003;348:347-9.
  34. Michaelsson K, Lithell H, Vessby B, Melhus H. Serum retinol levels and the risk of fracture. N Engl J Med 2003;348:287-94.
  35. Denke MA. Dietary retinol--a double-edged sword. JAMA 2002;287:102-4.
  36. Semba RD, Kumwenda N, Taha TE, et al. Impact of vitamin A supplementation on anaemia and plasma erythropoietin concentrations in pregnant women: a controlled clinical trial. Eur J Haematol 2001;66:389-95.
  37. Zimmerman CL, Han S, Wiedmann TS. The absorption of retinoic acids from the gastrointestinal tract is dependent upon chemical structure. Cancer Chemother Pharmacol 2001;47:27-33.
  38. Harrison EH, Hussain MM. Mechanisms involved in the intestinal digestion and absorption of dietary vitamin A. J Nutr 2001;131:1405-8.
  39. Rahman MM, Wahed MA, Fuchs GJ, et al. Synergistic effect of zinc and vitamin A on the biochemical indexes of vitamin A nutrition in children. Am J Clin Nutr 2002;75:92-8.
  40. Christian P, Khatry SK, Yamini S, et al. Zinc supplementation might potentiate the effect of vitamin A in restoring night vision in pregnant Nepalese women. Am J Clin Nutr 2001;73:1045-51.
  41. Kumar B, Cole WC, Prasad KN. Alpha tocopheryl succinate, retinoic acid and polar carotenoids enhanced the growth-inhibitory effect of a cholesterol-lowering drug on immortalized and transformed nerve cells in culture. J Am Coll Nutr 2001;20:628-36.
  42. Prakash P, Russell RM, Krinsky NI. In vitro inhibition of proliferation of estrogen-dependent and estrogen-independent human breast cancer cells treated with carotenoids or retinoids. J Nutr 2001;131:1574-80.
  43. Hickenbottom SJ, Follett JR, Lin Y, et al. Variability in conversion of beta-carotene to vitamin A in men as measured by using a double-tracer study design. Am J Clin Nutr 2002;75:900-7.
  44. Pastorino U, Infante M, Maioli M, et al. Adjuvant treatment of stage I lung cancer with high-dose vitamin A. J Clin Oncol 1993;11:1216-22.
  45. 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 Intern Med 1998;129:770-8.
  46. Feskanich D, Singh V, Willett WC, Colditz GA. Vitamin A intake and hip fractures among postmenopausal women. JAMA 2002;287:47-54.
  47. Leo MA, Lieber CS. Alcohol, vitamin A, and beta-carotene: adverse interactions, including hepatotoxicity and carcinogenicity. Am J Clin Nutr 1999;69:1071-85.
  48. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2002. Available at: www.nap.edu/books/0309072794/html/.
  49. Widschwendter M, Berger J, Hermann M, et al. Methylation and silencing of the retinoic acid receptor-beta2 gene in breast cancer. J Natl Cancer Inst 2000;92:826-32.
  50. Sporn MB. Retinoids and demethylating agents-looking for partners. J Natl Cancer Inst 2000;92:780-1.
  51. Cumming RG, Mitchell P, Smith W. Diet and cataract: the Blue Mountains Eye Study. Ophthalmology 2000;10:450-6.
  52. Russell RM. The vitamin A spectrum: from deficiency to toxicity. Am J Clin Nutr 2000;71:878-84.
  53. Fawzi WW, Msamanga G, Hunter D, et al. Randomized trial of vitamin supplements in relation to vertical transmission of HIV-1 in Tanzania. J Acquir Immune Defic Syndr 2000;23:246-54.
  54. Christian P, West KP Jr, Khatry SK, et al. Vitamin A or beta-carotene supplementation reduces but does not eliminate maternal night blindness in Nepal. J Nutr 1998;128:1458-63.
  55. West KP Jr, Katz J, Khatry SK, et al. Double-blind cluster, randomised trial of low dose supplementation with vitamin A or beta carotene on mortality related to pregnancy in Nepal. The NNIPS-2 Study Group. BMJ 1999;318:570-5.
  56. Katz J, West KP Jr, Khatry SK, et al. Maternal low-dose vitamin A or {beta}-carotene supplementation has no effect on fetal loss and early infant mortality: a randomized, cluster trial in Nepal. Am J Clin Nutr 2000;71:1570-6.
  57. Kligman AM. Topical treatments for photoaged skin. Separating the reality from the hype. Postgrad Med 1997;102:115-26.
  58. Clark JH, Russell GJ, Fitzgerald JF, et al. Serum beta-carotene, retinol, and alpha-tocopherol levels during mineral oil therapy for constipation. Am J Dis Child 1987;141:1210-2.
  59. Becker GL. The case against mineral oil. Am J Digestive Dis 1952;19:344-8.
  60. Tonstad S, Silverstein M, Aksnes L, Ose L. Low dose colestipol in adolescents with familial hypercholesterolemia. Arch Dis Child 1996;74:157-60.
  61. Schwarz KB, Goldstein PD, Witztum JL, et al. Fat-soluble vitamin concentrations in hypercholestrolemic children treated with colestipol. Pediatrics 1980;65:243-50.
  62. Elinder LS, Hadell K, Johansson J, et al. Probucol treatment decreases serum concentrations of diet-derived antioxidants. Arterioscler Thromb Vasc Biol 1995;15:1057-63.
  63. West RJ, Lloyd JK. The effect of cholestyramine on intestinal absorption. Gut 1975;16:93-8.
  64. Hathcock JN. Metabolic mechanisms of drug-nutrient interactions. Fed Proc 1985;44:124-9.
  65. FDA Talk Paper. Vitamin A and birth defects (T95-56). Food and Drug Administration, U.S. Department of Health and Human Services, Rockville, MD. October 6, 1995.
  66. Hansten PD, Horn JR. Drug Interactions Analysis and Management. Vancouver, WA: Applied Therapeutics Inc., 1997 and updates.
  67. Christian P, West KP, Khatry SK, et al. Vitamin A or beta-carotene supplementation reduces symptoms of illness in pregnant and lactating Nepali women. J Nutr 2000;130:2675-82.
  68. Roche, Inc. Xenical package insert. Nutley, NJ. May 1999.
  69. Melia AT, Koss-Twardy SG, Zhi J. The effect of orlistat, an inhibitor of dietary fat absorption, on the absorption of vitamins A and E in healthy volunteers. J Clin Pharmacol 1996;36:647-53.
  70. van Zandwijk N, Dalesio O, Pastorino U, et al. EUROSCAN, a randomized trial of vitamin A and N-acetylcysteine in patients with head and neck cancer or lung cancer. For the European Organization for Research and Treatment of Cancer Head and Neck and Lung Cancer Cooperative Groups. J Natl Cancer Inst 2000;92:977-86.
  71. Liu C, Russell RM, Seitz HK, et al. Ethanol enhances retinoic acid metabolism into polar metabolites in rat liver via induction of cytochrome P4502E1. Gastroenterology 2001;120:179-89.
  72. Meyers DG, Maloley PA, Weeks D. Safety of antioxidant vitamins. Arch Intern Med 1996;156:925-35.
  73. Wang Z, Boudjelal M, Kang S, et al. Ultraviolet irradiation of human skin causes functional vitamin A deficiency, preventable by all-trans retinoic acid pre-treatment. Nat Med 1999;5:418-22.
  74. Kowalski TE, Falestiny M, Furth E, Malet PF. Vitamin A hepatotoxicity: a cautionary note regarding 25,000 IU supplements. Am J Med 1994;97:523-8.
  75. Fawzi WW, Mbise RL, Fataki MR, et al. Vitamin A supplementation and severity of pneumonia in children admitted to the hospital in Dar es Salaam, Tanzania. Am J Clin Nutr 1998;68:187-92.
  76. Fawzi WW, Mbise RL, Hertzmark E, et al. A randomized trial of vitamin A supplements in relation to mortality among human immunodeficiency virus-infected and uninfected children in Tanzania. Pediatr Infect Dis J 1999;18:127-33.
  77. Shankar AH, Genton B, Semba RD, et al. Effect of vitamin A supplementation on morbidity due to Plasmodium falciparum in young children in Papua New Guinea: a randomised trial. Lancet 1999;354:203-9.
  78. Zhang S, Hunter DJ, Forman MR, et al. Dietary carotenoids and vitamins A, C, and E and risk of breast cancer. J Natl Cancer Inst 1999;91:547-56.
  79. Hardman JG, Limbird LL, Molinoff PB, eds. Goodman and Gillman's The Pharmacological Basis of Therapeutics, 9th ed. New York, NY: McGraw-Hill, 1996.
  80. Vetrugno M, Maino A, Cardia G, et al. A randomised, double masked, clinical trial of high dose vitamin A and vitamin E supplementation after photorefractive keratectomy. Br J Ophthalmol 2001;85:537-9.
  81. Wicke C, Halliday B, Allen D, et al. Effects of steroids and retinoids on wound healing. Arch Surg 2000;135:1265-70.
  82. Griffiths JK. The vitamin A paradox. J Pediatr 2000;137:604-7.
  83. McKevoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
Show more references
Show fewer references
Last reviewed - 08/02/2012

Browse Herbs & Supplements



Page last updated: 27 September 2012