Retinyl palmitate, or vitamin A palmitate, is the

ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...

retinol Retinol, also called vitamin A1, is a fat-soluble vitamin in the vitamin A family that is found in food and used as a dietary supplement. Retinol or other forms of vitamin A are needed for vision, cellular development, maintenance of skin and ...

(

vitamin A Vitamin A is a fat-soluble vitamin that is an essential nutrient. The term "vitamin A" encompasses a group of chemically related organic compounds that includes retinol, retinyl esters, and several provitamin (precursor) carotenoids, most not ...

) and

palmitic acid Palmitic acid (hexadecanoic acid in IUPAC nomenclature) is a fatty acid with a 16-carbon chain. It is the most common saturated fatty acid found in animals, plants and microorganisms.Gunstone, F. D., John L. Harwood, and Albert J. Dijkstra. The ...

, with formula C₃₆H₆₀O₂. It is the most abundant form of vitamin A storage in animals. An alternate spelling, retinol palmitate, which violates the -yl organic chemical naming convention for

s, is also frequently seen. In 2021, vitamin A was the 298th most commonly prescribed medication in the United States, with more than 500,000 prescriptions.

Biology

Animals use long-chain esters of vitamin A, most abundantly the palmitate form, as a form of vitamin A storage. The storage reaction is catalyzed by LRAT, and the inverse is catalyzed by REH. The esters are also intermediates in the visual cycle: RPE65 isomerizes the retinyl part to 11-cis-retinal.

Uses

Vitamin A palmitate is a common vitamin supplement, available in both oral and injectable forms for treatment of

vitamin A deficiency Vitamin A deficiency (VAD) or hypovitaminosis A is a lack of vitamin A in blood and tissues. It is common in poorer countries, especially among children and women of reproductive age, but is rarely seen in more developed countries. Vitamin A pla ...

, under the brand names Aquasol A, Palmitate A, and many others. It is a constituent of intraocular treatment for dry eyes at a concentration of 138 μg/g (VitA-Pos) by Ursapharm. It is a pre-formed version of vitamin A; therefore, the intake should not exceed the Recommended Dietary Allowance (RDA). Overdosing on preformed Vitamin A forms, such as retinyl palmitate, leads to adverse physiological reactions (

hypervitaminosis A Hypervitaminosis A refers to the toxic effects of ingesting too much preformed vitamin A (retinyl esters, retinol, and retinal). Symptoms arise as a result of altered bone metabolism and altered metabolism of other fat-soluble vitamins. Hype ...

). Retinyl palmitate is used as a source of

added to low-fat

milk Milk is a white liquid food produced by the mammary glands of lactating mammals. It is the primary source of nutrition for young mammals (including breastfeeding, breastfed human infants) before they are able to digestion, digest solid food. ...

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,

, 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 Retinoic acid (simplified nomenclature for all-''trans''-retinoic acid) is a metabolite of vitamin A1 (all-''trans''-retinol) that is required for embryonic development, male fertility, regulation of bone growth and immune function. All-''trans ...

(the active form of vitamin A present in Retin-A), though neither its skin absorption nor its conversion is very effective.

Carcinogenicity controversy

New York Senator

Chuck Schumer Charles Ellis Schumer ( ; born November 23, 1950) is an American politician serving as the Seniority in the United States Senate, senior United States Senate, United States senator from New York (state), New York, a seat he has held since 1999. ...

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 etinyl palmitatein sunscreens is carcinogenic." A technical report issued thereafter by the

National Toxicology Program The National Toxicology Program (NTP) is an inter-agency program run by the United States Department of Health and Human Services to coordinate, evaluate, and report on toxicology within public agencies. The National Toxicology Program is head ...

concluded that diisopropyl adipate increased the incidence of skin tumors in mice, and the addition of either

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

reformed Reform is beneficial change. Reform, reformed or reforming may also refer to: Media * ''Reform'' (album), a 2011 album by Jane Zhang * Reform (band), a Swedish jazz fusion group * ''Reform'' (magazine), a Christian magazine Places * Reform, Al ...

vitamin A (3000 μg RE) at any time during pregnancy.". Preformed Vitamin A refers to retinyl palmitate and retinyl acetate.

References

{{Retinoid receptor modulators Antioxidants Cyclohexenes Palmitate esters Retinoids Vitamins Orphan drugs

Biology

Uses

Carcinogenicity controversy

Teratogenicity

See also

References