Vitamin A (Retinol)

Vitamin A is important in maintaining good vision, healthy skin, and healthy mucous membranes. Research has shown it is also necessary for proper immune system function. Vitamin A is also important for proper growth, bone formation, reproduction, and wound healing. Your liver can store up to a year's supply of vitamin A. The stored supply of this vitamin is used up more quickly if you become ill or have an infection.

Uses

• Acne and psoriasis. Drugs including vitamin A successfully clear up acne and psoriasis. Even more recently, another drug made from vitamin A is helping to lessen scars and wrinkles on the skin, making them less noticeable, and helping to prevent wrinkles from forming.
• Immune system. Research has shown that vitamin A boosts the immune system to help fight off illness and infection, especially viral illness.
• Wound healing. Your body needs vitamin A, along with several other nutrients, when it is forming new tissue and skin.
• Measles. Reduces infant mortality from this disease
• Also used to treat night blindness and hyperkeratosis

Dietary Sources

Vitamin A is found only in foods from animal sources, especially beef, calf, and chicken liver. Dairy products such as milk, butter, cheese, and ice cream are also good sources. However, beta-carotene, a nutrient found in fruits and vegetables, can be converted to vitamin A in the body as needed. Most dark-green leafy vegetables and most orange vegetables and fruits contain a lot of beta-carotene, and by eating these foods you will increase your body's supply of vitamin A. Vegetables such as sweet potatoes, carrots, and winter squash, and fruits such as cantaloupe and mango are all good sources of beta-carotene.

Other Forms

You can buy natural vitamin A supplements either as retinol or retinyl palmitate. All forms of vitamin A are easily absorbed. Tablets or capsules are available in 10,000 IU, 25,000 IU, and 50,000 IU doses. Your health care provider will help you decide which vitamin A dosage is best for you. Most multivitamins contain the recommended dietary allowance (RDA) for vitamin A. If you are taking a multivitamin, you are probably getting more than enough vitamin A to meet your average needs. You should never take more than 25,000 IU per day (10,000 IU for children) without a health care provider's supervision.

In many cases, taking beta-carotene, the precursor form of vitamin A, is a safer alternative to taking vitamin A. Unlike vitamin A, beta-carotene is water-soluble and does not build up in the body, so it can be taken in larger amounts without the same risk. This makes it a better alternative for children, adults with liver or kidney disease, and pregnant women.

How to Take It

Vitamin A is a fat-soluble vitamin and is absorbed along with the fat in your diet. Supplements containing vitamin A should be taken during or shortly after a meal.

Precautions

Pregnant women should never take vitamin A supplements, because they can cause birth defects. All prenatal vitamins contain some vitamin A, and taking any more would be dangerous to the fetus.

Too much vitamin A is toxic to the body and can even be fatal. You probably won't get toxic amounts of vitamin A from your daily diet, but taking vitamin A supplements without a health care provider's supervision is not recommended. Vitamin A is found in many different types of vitamin formulas. For example, supplements that say "wellness formula," "immune system formula," "cold formula," "eye health formula," "healthy skin formula," or "acne formula," all may contain vitamin A. If you take a variety of different formulas, you could put yourself at risk for vitamin A toxicity. Some of the symptoms of vitamin A toxicity are lasting headache, fatigue, muscle and joint pain, dry, cracking skin and lips, dry, irritated eyes, nausea or diarrhea, and hair loss.

Alcohol use makes vitamin A toxicity more likely. Consuming more than 25,000 IU of vitamin A per day (adults) and 10,000 IU per day (children) from either food or supplements or both can be toxic. Do not take vitamin A supplements if you are using Accutane, Retin-A or any vitamin A–derived drugs used to treat acne, psoriasis, and other skin problems.

Possible Interactions

The cholesterol-lowering medications cholestyramine and colestipol interfere with the absorption of vitamin A.

Supporting Research

Eades MD. The Doctor's Complete Guide to Vitamins and Minerals. New York, NY: Dell Publishing; 1994:48.

Fawzi WW. Vitamin A supplementation and child mortality. JAMA. 1993;269:898–903.

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;18:127–133.

Fortes C, Forastiere F, Agabiti N, et al. The effect of zinc and vitamin A supplementation on immune response in an older population. J Am Geriatr Soc. 1998;46:19–26.

Futoryan T, Gilchrest BA. Retinoids and the skin. Nutr Rev. 1994;52:299–310.

Kindmark A, Rollman O, Mallmin H, et al. Oral isotretinoin therapy in severe acne induces transient suppression of biochemical markers of bone turnover and calcium homeostasis. Acta Derma Venereol. 1998;78:266–269.

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;129:770–778.

Murray M. Encyclopedia of Nutritional Supplements. Rocklin, Calif: Prima Publishing; 1996.

Nursing ‘93 Drug Handbook. Springhouse, Pa: Springhouse Corporation; 1993.

Physicians' Desk Reference. 53rd ed. Montvale, NJ: Medical Economics Co., Inc.;1999:857-859.

Semba RD. Vitamin A, immunity and infection. Clin Infect Dis. 1994;19:489–499.

Whitney E, Cataldo C, Rolfes S. Understanding Normal and Clinical Nutrition. St. Paul, Minn: West Publishing Company; 1987.

Copyright © 2000 Integrative Medicine Communications

The publisher does not accept any responsibility for the accuracy of the information or the consequences arising from the application, use, or misuse of any of the information contained herein, including any injury and/or damage to any person or property as a matter of product liability, negligence, or otherwise. No warranty, expressed or implied, is made in regard to the contents of this material. No claims or endorsements are made for any drugs or compounds currently marketed or in investigative use. This material is not intended as a guide to self-medication. The reader is advised to discuss the information provided here with a doctor, pharmacist, nurse, or other authorized healthcare practitioner and to check product information (including package inserts) regarding dosage, precautions, warnings, interactions, and contraindications before administering any drug, herb, or supplement discussed herein.