Q. I’m thinking about taking a vitamin A supplement, but am confused by the various types. What’s the best kind?
A. If you’re eating a balanced diet and have no special health concerns, you probably don’t need extra vitamin A of any kind. According to the Office of Dietary Supplements of the National Institutes of Health, “Vitamin A is available in multivitamins and as a stand-alone supplement, often in the form of retinyl acetate or retinyl palmitate [“preformed” vitamin A]. A portion of the vitamin A in some supplements is in the form of beta-carotene and the remainder is preformed vitamin A; others contain only preformed vitamin A or only beta-carotene. Supplement labels usually indicate the percentage of each form of the vitamin. The amounts of vitamin A in stand-alone supplements range widely. Multivitamin supplements typically contain 2,500–10,000 IU vitamin A, often in the form of both retinol and beta-carotene.”
Although an issue in developing countries, Vitamin A deficiency is rare in the United States. The Institute of Medicine advises against beta-carotene supplements for the general population, except as a provitamin A source to prevent vitamin A deficiency. If you are a current or former smoker, you should be aware that studies have linked supplementation with beta-carotene to increased risk of lung cancer and cardiovascular disease in current and ex-smokers.
The original Age-Related Eye Disease Study (AREDS) did support a supplement formulation including beta carotene for those at risk for age-related macular degeneration (AMD). The most recent AREDS research, however, led to a recommendation to replace beta-carotene with lutein and zeaxanthin. (See the August 2013 newsletter.)