Vitamin A (Retinol)

Content provided by the Faculty of the Harvard Medical School

Vitamin A (Retinol)

Be aware that the U.S. Food and Drug Administration does not strictly regulate herbs and dietary supplements. There is no guarantee of strength, purity or safety of products containing or claiming to contain vitamin A. Decisions to use herbs or supplements should be carefully considered. Individuals using prescription drugs should discuss taking herbs or supplements with their pharmacists or health care professionals before starting.

Evidence

Scientists have studied vitamin A for the following health problems:

Vitamin A deficiency

Vitamin A deficiency may occur after long-term lack of vitamin A or beta-carotene. Vitamin A is necessary for vision. An early sign of vitamin A deficiency is night blindness (keratomalacia). A prolonged lack of vitamin A may lead to dry eye (xerophthalmia). Eventually, blindness can occur. Vitamin A is needed for healthy growth and development, and especially children should have recommended daily amounts (RDA).

Acne

Retinoids are by-products of vitamin A, and are used to treat skin disorders such as acne. Drugs taken by mouth and applied to the skin are available. Examples include tretinoin (Avita, Renova, Retina-A, Retin-A Micro) and isotretinoin (Accutane). Isotretinoin may cause severe side effects and should be used only for severe acne. Isotretinoin must not be used in women who are pregnant, plan to become pregnant, or have a chance of being pregnant due to a risk of severe birth defects. These medications should be prescribed and monitored by a qualified licensed healthcare professional. Vitamin A supplements should not be used at the same time due to increased risk of dangerous side effects.

Acute promyelocytic leukemia (All-trans retinoic acid)

The prescription drug All-Trans-Retinoic Acid (ATRA, Vesanoid) is a vitamin A by-product. It is used to treatment acute promyelocytic leukemia and improves survival in this disease. Treatment should be under strict medical supervision. Vitamin A supplements should not be used at the same time as ATRA due to increased risk of dangerous side effects.

Measles

Vitamin A should be administered to children with measles in countries where vitamin A deficiency may be present. Management of measles should be under strict medical supervision.

Xerophthalmia (dry eye)

Taking vitamin A by mouth is the treatment of choice for xerophthalmia that is due to prolonged vitamin A deficiency. Please consult your eye care professional before taking vitamin A supplements.

Malaria

Some research suggests that vitamin A may reduce fever, disease rate, and parasite blood levels in patients with malaria (Plasmodium falciparum infection). However, there is no evidence that vitamin A is as good as or better than standard drug therapies used for prevention or treatment of malaria. Patients with malaria or living/traveling in endemic areas should speak with their physician.

Retinitis pigmentosa

Retinitis pigmentosa is a genetic disorder that affects night vision. Based on recent findings, 15,000 IU daily of vitamin A in the palmitate form has been recommended in patients with retinitis pigmentosa.

Antioxidant

The benefits to humans of potential antioxidant activity are not clear.

Breast cancer

Vitamin A may be beneficial in the treatment or prevention of breast cancer, but research is not clear. Patients receiving chemotherapy or radiation therapy for cancer should speak with their doctors and pharmacist before taking antioxidants such as vitamin A during treatment, due to possible interference with other therapies.

Cataract prevention

Vitamin A may prevent cataracts. Further research is needed before a recommendation can be made.

Diarrhea

Vitamin A may reduce episodes in malnourished children but not in well-nourished children. Since diarrhea is a major cause of disease and death in developing countries, vitamin A supplementation may be beneficial for undernourished children with diarrhea.

HIV Infection

The role of vitamin A in the prevention, transmission, or treatment of HIV is controversial and not well established. A clear conclusion cannot be formed based on the available scientific research.

Immune function

Vitamin A deficiency may compromise immunity, but there is no clear evidence that additional vitamin A supplementation is beneficial for immune function in patients who are not vitamin A deficient.

Infant mortality

Some evidence suggests possible decreases in infant death with vitamin A supplementation, while other research reports no benefits.

Iron deficiency anemia

Vitamin A and iron supplements may help patients with iron deficiency anemia, including children and pregnant women. This may not help people who are not vitamin A deficient.

Photoreactive keratectomy

Photoreactive keratectomy is a type of laser eye surgery used to correct nearsightedness. High-dose vitamin A supplementation (50,000 to 75,000 units) in addition to vitamin E (230mg) may help improve eye healing after surgery and to improve visual focus, although additional evidence is necessary.

Polyp prevention

Alpha-carotene and vitamin A may protect against the return of polyps and some non-cancerous tumors in nonsmokers and nondrinkers. Further research is needed.

Pregnancy-related complications

Vitamin A deficiency in pregnant women is common in developing countries. Some vitamins may reduce pregnancy-related complications and death in such individuals. However, too much vitamin A has been reported to increase the risks of some birth defects. Vitamin A supplementation above the RDA is therefore not recommended in pregnancy.

Skin cancer prevention

It is not clear if vitamin A taken by mouth or used on the skin with sunscreen, helps prevent or treat skin cancers.

Weight loss

Daily vitamin A with calcium has been suggested for weight loss, and in one study an average loss of 2 pounds was reported after two years of supplementation in young women.

Wound healing

In early study, a type of vitamin A (retinol palmitate) significantly reduced rectal symptoms of radiation proctopathy, perhaps because of wound-healing effects. Further research is needed to confirm these results.

Lung cancer

Vitamin A has been studied as a possible treatment for lung cancer, without evidence of benefits. High-dose Vitamin A and beta-carotene may actually increase the risk of adverse effects, especially among alcohol users and smokers.

Chemotherapy adverse effects

Vitamin A supplementation does not appear to improve chemotherapy-related side effects including nausea, vomiting, diarrhea, or mouth sores.

Unproven Uses

Vitamin A has been suggested for many other uses, based on tradition or on scientific theories. However, these uses have not been thoroughly studied in humans, and there is limited scientific evidence about safety or effectiveness. Some of these suggested uses are for conditions that are potentially very serious and even life-threatening. You should consult a health care professional before taking vitamin A for any unproven use.

Aging Allergic rhinitis Asthma Atrophic rhinitis Atrophic vaginitis Blurred vision Bronchopulmonary dysplasia in premature infants Burns Cancer prevention Candidiasis Cellulite (topical retinal) Cold sores Conjunctivitis Crohn’s disease Cystic fibrosis Deafness Diabetes Eczema Enhancing tissue integrity Fibrocystic breast disease Gastrointestinal disorders Glaucoma Heart disease Hurler syndrome Hyperthyroidism Ichthyosis Infections

Keratosis follicularis (Darier's disease) Kidney stones Leukoplakia Lichen planus pigmentosus Liver disease Myopia (nearsightedness) Neurodegenerative diseases Painful menstruation Periodontal disease Persistent headache Pityriasis rubra pilaris Plantar warts Pneumonia Pollutant protection Premenstrual syndrome Protein deficiency Psoriasis Reduced sperm count Sebaceous cysts Sinusitis Stress ulcers in severely ill hospitalized patients Sunburn Tinnitus Ulcers Urinary tract infections Wounds Wrinkles

Potential Dangers

Allergies

You should avoid vitamin A supplements or drugs if you have a known hypersensitivity or allergy to vitamin A.

Side Effects

Too much vitamin A is rare. Vitamin A toxicity can occur with too much vitamin A is taken over short or long periods of time. An infant with toxicity can develop a bulging fontalle (the soft spot on the head) and symptoms similar to a brain tumor. Adults can have symptoms such as headache, dizziness, tiredness, feeling “unwell”, blurry vision, bone pain and swelling, nausea, and/or vomiting. Severe toxicity can lead to eye damage, high levels of calcium, and liver damage. People with liver disease and high alcohol intake may be at risk for severe liver damage from vitamin A supplementation. Smokers who consume alcohol and beta-carotene may be at an increased risk for lung cancer or cardiovascular disease.

Pregnancy And Breast-Feeding

U.S. Institute of Medicine of the National Academy of Sciences established the followingRecommended Daily Allowances (RDAs) for vitamin A:

Pregnant women between 14-18 years-old: 750mcg/day (2500 IU)
Pregnant women 19 years and older: 770mcg/day (2600 IU)
Breastfeeding women between 14-18 years-old: 1200mcg/day (4000 IU)
Breastfeeding women 19 years and older: 1300mcg/day (4300 IU)

Vitamin A should only be used within the recommended dietary allowance, because too much Vitamin A may cause birth defects. Large doses of vitamin A may cause central nervous system defects.

Mothers can pass vitamin A to their infants through breast milk. Benefits or dangers to nursing infants are not clearly established.

Interactions

Interactions with drugs, supplements and other herbs have not been thoroughly studied. The interactions listed below have been reported in scientific publications. If you are taking prescription drugs, speak with your health care professional or pharmacist before using herbs or dietary supplements.

Interactions With Drugs

The following drugs increase the risk of vitamin A toxicity: Acitretin (Soriatane), All-Trans-Retinoic Acid (ATRA, Vesanoid), Bexarotene (Targentin), blood thinners like warfarin (Coumadin), Etretinate (Tegison), Isotretinoin (Accutane, Amnesteen), Tretinoin (Vesabiod, Avita, Renova, Retin-A, Retin-A Micro, Altinac), and other vitamin A supplements.

Some drugs may affect how Vitamin A is absorbed by the body. These drugs include:

bile acid sequestrants like cholestyramine (Questran) and colestipol (Colestid), mineral oil,

Neomycin (Mycifradin, Neo-Fradin, and Orlistat (Xenical).

Birth control pills and estrogens may increase plasma vitamin A levels.

Vitamin A may reduce the effectiveness of the measles virus/vaccine.

People taking tetracycline antibiotics, specifically minocycline (Minocin), and vitamin A are at a risk for developing high blood pressure in the skull (pseudotumor cerebri). This can happen with too much tetracyclines and vitamin A. Therefore, high doses of vitamin A should be avoided in people taking these antibiotics. Other examples of tetracyclines include demeclocycline (Declomycin) and tetracycline (Achromycin).

Interactions With Herbs And Dietary Supplements

Carob may increase the risk of vitamin A toxicity.

Zinc deficiency may alter vitamin A status, although how is unclear.

Vitamin A may improve anemia in people who are deficient in iron and vitamin A. There is likely no benefit in people who are not vitamin A deficient.

Interactions with Food

High intake of olestra reduces vitamin A.

Eating orange-fleshed sweet potato has been shown to improve vitamin A status.

Dosing

The doses listed below are based on scientific research, publications or traditional use. Because most herbs and supplements have not been thoroughly studied or monitored, safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients even within the same brand. Combination products often contain small amounts of each ingredient and may not be effective. The appropriate dosing should be discussed with a health care professional before starting therapy; always read the recommendations on a product's label. The dosing for unproven uses should be approached cautiously, because scientific information is limited in these areas.

U.S. Recommended Daily Allowance (RDA)

Adults (Aged 18 Or Older)

By mouth: The U.S. Institute of Medicine of the National Academy of Sciences has established the following RDAs:

Men: 900mcg/day (3000 IU)
Women: 700 mcg/day (2300 IU)
Pregnant women 19 years and older: 770mcg/day (2600 IU)
Breastfeeding women 19 years and older: 1300mcg/day (4300 IU)

Children (Younger Than 18)

By mouth: The U.S. Institute of Medicine of the National Academy of Sciences has established the following RDAs:

Children 1-3 years-old: 300mcg/day (1000 IU)
Children 4-8 years-old: 400mcg/day (1300 IU)
Children 9-13 years-old: 600mcg/day (2000 IU)

Pregnant or Breastfeeding

By mouth:

Pregnant women between 14-18 years-old: 750mcg/day (2500 IU)
Breastfeeding women between 14-18 years-old: 1200mcg/day (4000 IU)
Pregnant women 19 years and older: 770mcg/day (2600 IU)
Breastfeeding women 19 years and older: 1300mcg/day (4300 IU)

Vitamin A deficiency:

Adults (Aged 18 Or Older)

By mouth: 100,000 IU orally administered daily for 3 days, followed by 50,000 IU per day for 2 weeks has been used. A maintenance dose of 10,000 to 20,000 IU per day for 2 months has been recommended.

By injection: 100,000 IU administered daily for 3 days, followed by 50,000 IU per day for 2 weeks has been used. A maintenance dose of 10,000 to 20,000 IU per day for 2 months has been recommended.

Children (Younger Than 18)

By mouth: The World Health Organization (WHO) has established dosage guidelines for children between 6-11 months-old to receive 100,000 IU of vitamin A. This increases to 200,000 IU every six months from 12 to 59 months of age.

Xerophthalmnia

Adults (Aged 18 Or Older)

By mouth: 200,000 IU immediately of vitamin A in an oil-based preparation. The same dose should be repeated the following day, after diagnosis of xerophthalmnia, and 2 weeks later.

Children (Younger Than 18)

Children 6 months-old to 1 year-old: 100,000 IU by mouth as a single dose, repeated the next day and again at 4 weeks.

Children 1 year-old or older: 200,000 IU as a single dose, repeated the next day and again at 4 weeks.

Measles

Children (Younger Than 18)

By mouth: Vitamin A should be given to children diagnosed with measles in areas where vitamin A deficiency may be present. The recommended dose is 100,000 IU for children 6 months-old to 1 year-old, and 200,000 IU for children older than 12 months-old. The dose should be repeated the next day and again after at least 2 weeks. Vitamin A deficiency is not recognized as a problem in the United States, and supplementation above the RDA should only be given in special situations under strict medical supervision.

Summary

Research suggests that vitamin A may reduce the death rate from measles, prevent some types of cancer, aid in growth and development, and improve immune function.

The U.S. Institute for Medicine of the National Academy of Sciences established recommended daily allowance (RDA) levels for vitamin A doses by mouth to prevent deficiencies in vitamin A.At recommended doses, vitamin Ais generally considered non-toxic. Excess dosing may lead to serious health problems.

Vitamin A deficiency is rare in industrialized nations but remains a concern in developing countries, particularly in areas where malnutrition is common. Long-term deficiency can lead to dry eye (xerophthalmia) and ultimately to night blindness or total blindness, as well as to skin disorders, infections (such as measles), diarrhea, and respiratory disorders.

The information in this monograph was prepared by the professional staff at Natural Standard, based on thorough systematic review of scientific evidence. The material was reviewed by the Faculty of the Harvard Medical School with final editing approved by Natural Standard.

Resources

Natural Standard: An organization that produces scientifically based reviews of complementary and alternative medicine (CAM) topics
National Center for Complementary and Alternative Medicine (NCCAM): A division of the U.S. Department of Health & Human Services dedicated to research

Selected Scientific Studies: Vitamin A

Natural Standard reviewed more than 1420 articles to prepare the professional monograph from which this version was created.

Some of the more recent studies are listed below:

Ambalavanan N, Tyson JE, Kennedy KA, et al. Vitamin A supplementation for extremely low birth weight infants: outcome at 18 to 22 months. Pediatrics 2005;115(3):e249-e254.
Berson EL, Rosner B, Sandberg MA, et al. Clinical trial of docosahexaenoic acid in patients with retinitis pigmentosa receiving vitamin A treatment. Arch Ophthalmol 2004;122(9):1297-1305.
Bishai D, Kumar KCS, Waters H, et al. The impact of vitamin A supplementation on mortality inequalities among children in Nepal. Health Policy Plan 2005;20(1):60-66
Ehrenpreis ED, Jani A, Levitsky J, et al. A prospective, randomized, double-blind, placebo-controlled trial of retinol palmitate (vitamin A) for symptomatic chronic radiation proctopathy. Dis Colon Rectum 2005;48(1):1-8
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(5):660-667.
Feskanich D, Singh V, Willett WC, et al. Vitamin A intake and hip fractures among postmenopausal women. JAMA 2002;287(1):47-54.
Goldsmith LA, Bolognia JL, Callen JP, et al. American Academy of Dermatology Consensus Conference on the safe and optimal use of isotretinoin: summary and recommendations. J Am Acad Dermatol 2004;50(6):900-906.
Haskell MJ, Pandey P, Graham JM, et al. Recovery from impaired dark adaptation in nightblind pregnant Nepali women who receive small daily doses of vitamin A as amaranth leaves, carrots, goat liver, vitamin A-fortified rice, or retinyl palmitate. Am J Clin Nutr 2005;81(2):461-471.
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(6):1570-1576.
Kokkonen J, Mottonen M, Karttunen TJ, et al. 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(3):181-192.
Lanvers C, Reinhardt D, Dubbers A, et al. Pharmacology of all-trans-retinoic acid in children with acute promyelocytic leukemia. Med Pediatr Oncol 2003;40(5):293-301.
Malaba LC, Iliff PJ, Nathoo KJ, et al. Effect of postpartum maternal or neonatal vitamin A supplementation on infant mortality among infants born to HIV-negative mothers in Zimbabwe. Am J Clin Nutr 2005;81(2):454-460.
McDuffie JR, Calis KA, Booth SL, et al. Effects of orlistat on fat-soluble vitamins in obese adolescents. Pharmacotherapy 2002;22(7):814-822.
Michels KB, Holmberg L, Bergkvist L, et al. Dietary antioxidant vitamins, retinol, and breast cancer incidence in a cohort of Swedish women. Int J Cancer 2001;91(4):563-567.
Rahmathullah L, Tielsch JM, Thulasiraj RD, et al. Impact of supplementing newborn infants with vitamin A on early infant mortality: community based randomised trial in southern India. BMJ 2003;327(7409):254.
Russell RM. The vitamin A spectrum: from deficiency to toxicity. Am J Clin Nutr 2000;71(4):878-884.
Semba RD, Ndugwa C, Perry RT, et al. Effect of periodic vitamin A supplementation on mortality and morbidity of human immunodeficiency virus-infected children in Uganda: A controlled clinical trial. Nutrition 2005;21(1):25-31.
Steck-Scott S, Forman MR, Sowell A, et al. Carotenoids, vitamin A and risk of adenomatous polyp recurrence in the polyp prevention trial. Int J Cancer 2004;112(2):295-305.
Tulley RT, Vaidyanathan J, Wilson JB, et al. Daily intake of multivitamins during long-term intake of olestra in men prevents declines in serum vitamins A and E but not carotenoids. J Nutr 2005;135(6):1456-1461.
van Jaarsveld PJ, Faber M, Tanumihardjo SA, et al. Beta-carotene-rich orange-fleshed sweet potato improves the vitamin A status of primary school children assessed with the modified-relative-dose-response test. Am J Clin Nutr 2005;81(5):1080-1087.
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(5):537-539.
Zimmermann MB, Wegmuller R, Zeder C, et al. The effects of vitamin A deficiency and vitamin A supplementation on thyroid function in goitrous children. J Clin Endocrinol Metab 2004;89(11):5441-5447.

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Last updated:	August 21, 2006

Medical content reviewed by the Faculty of the Harvard Medical School. Harvard Health Publications, Copyright © 2007 by President and Fellows of Harvard College. All rights reserved. Used with permission of StayWell.

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