Retinyl acetate is a synthetic alternate for retinyl palmitate in vitamin A supplements, and is available in oily or dry forms. It is a common vitamin supplement, available in both oral and injectable forms for treatment of vitamin A deficiency, under the brand names Aquasol A, Palmitate A and many others. It is a constituent of intra ocular treatment for dry eyes at a concentration of 138 μg/g by Ursapharm. It is a pre-formed version of vitamin A; therefore, the intake should not exceed the Recommended Dietary Allowance. Overdosing preformed Vitamin A forms such as retinyl palmitate leads to adverse physiological reactions. Retinyl palmitate is used as an antioxidant and a source of vitamin A added to low fat milk and other dairy products to replace the vitamin content lost through the removal of milk fat. Palmitate is attached to the alcohol form of vitamin A, retinol, in order to make vitamin A stable in milk. Retinyl palmitate is also a constituent of some topically applied skin care products. After its absorption into the skin, retinyl palmitate is converted to retinol, and ultimately to retinoic acid, though neither its skin absorption nor its conversion is very effective.
Carcinogenicity controversy
New YorkSenator Chuck Schumer has called attention to the fact that high doses of topical retinyl palmitate were shown to accelerate cancer in lab animals, fueling the sunscreen controversy in the popular press. One toxicological analysis determined that "there is no convincing evidence to support the notion that in sunscreens is carcinogenic." A technical report issued thereafter by the National Toxicology Program concluded that diisopropyl adipate increased incidence of skin tumors in mice, and the addition of either retinoic acid or retinyl palmitate both exacerbated the rate and frequency of tumors.
Teratogenicity
World Health Organization recommendation on Maternal Supplementation During Pregnancy states that "health benefits are expected for the mother and her developing fetus with little risk of detriment to either, from a daily supplement not exceeding 10,000 IU vitamin A at any time during pregnancy." Preformed Vitamin A refers to retinyl palmitate and retinyl acetate.
