Vitamin A : Health Benefits, Part 2

by MedlinePlus

(Page 2 of 3)

Diarrhea

Vitamin A may reduce the severity and duration of diarrheal episodes in malnourished children but not in well-nourished children. Since diarrhea is a major cause of morbidity and mortality in developing countries, vitamin A supplementation may be considered in 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

There is a limited amount of research in this area, with mixed results. Some evidence suggests possible decreases in infant mortality with vitamin A supplementation, while other research reports no benefits. A clear conclusion cannot be formed based on the available scientific research.

Iron deficiency anemia

Vitamin A supplementation in combination with iron may have beneficial effects in patients with iron deficiency anemia, including children and pregnant women. It is not clear that there are benefits in individuals who are not vitamin A deficient. This area remains controversial, and further evidence is necessary before a clear conclusion can be drawn.

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) has been suggested to help improve ocular healing after surgery and to improve visual acuity, although additional evidence is necessary before a definitive conclusion can be reached.

Polyp prevention

Alpha-carotene and vitamin A may protect against recurrence of polyps and adenoma in nonsmokers and nondrinkers or be indicative of compliance or another healthy lifestyle factor that reduces risk. Further research is needed before a conclusion can be drawn

Pregnancy-related complications

Maternal vitamin A deficiency is common in developing countries. Beta-carotene may reduce pregnancy-related complications and mortality in such individuals. However, excess intake of 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 or beta-carotene, taken by mouth or used on the skin with sunscreen, is beneficial in the prevention or treatment of 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 preliminary study, 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. Available evidence suggests that 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.

Uses based on tradition or theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

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, menorrhagia, myopia (nearsightedness), neurodegenerative diseases, 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.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Standardization:

As retinol activity equivalents (RAEs), 1 RAE = 1 mcg retinal, 12 mcg beta-carotene, 24 mcg alpha-carotene, or 24 mcg beta cryptoxanthin in foods. To calculate RAEs from REs of provitamin A carotenoids in foods, divide the REs by 2. For preformed vitamin A in foods or supplements and for provitamin A carotenoids in supplements, 1 RE=1 RAE.

Sources of vitamin A: Vitamin A is found in dairy products, fish, darkly colored fruits and vegetables. Consumption of 5 servings of fruits and vegetables per day supplies 5 to 6 mg per day of provitamin A carotenoids, which provides about 50-65% of the adult RDA for vitamin A.

Adults (18 years and older):

U.S. Recommended Daily Allowance (RDA) for adults: RDAs have been established by the U.S. Institute of Medicine of the National Academy of Sciences. Recommendations are: 900mcg/day (3000 IU) for men; 700 mcg/day (2300 IU) for women. For pregnant women between 14-18 years-old, 750mcg/day (2500 IU) is recommended; for pregnant women 19 years and older, 770mcg/day (2600 IU) is recommended. For lactating women between 14-18 years-old, 1200mcg/day (4000 IU) is recommended; for lactating women 19 years and older, 1300mcg/day (4300 IU) is recommended.

Multivitamins: Vitamin A is included in most multivitamins, often in 5000 IU doses as softgels, capsules, tablets, or liquid.

Vitamin A deficiency: For vitamin A deficiency not involving xerophthalmia, 100,000 IU orally or intramuscularly 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.

Xerophthalmia: Oral vitamin A is the treatment of choice for xerophthalmia and should be given immediately once the disorder is established. Patients should obtain 200,000 IU immediately of vitamin A in an oil-based preparation. The same dose should be repeated the following day and 2 weeks later.

Children (younger than 18 years):

Recommended Dietary Allowance (RDA): RDAs have been established by the U.S. Institute of Medicine of the National Academy of Sciences. Recommendations are: For children 1-3 years-old, 300mcg/day (1000 IU); for children 4-8 years-old, 400mcg/day (1300 IU); for children 9-13 years-old, 600mcg/day (2000 IU). For pregnant women between 14-18 years-old, 750mcg/day (2500 IU) is recommended; for lactating women between 14-18 years-old, 1200mcg/day (4000 IU) is recommended.

Vitamin A deficiency/prevention: 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.

Xerophthalmia: 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: Vitamin A should be administered 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.

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