Retinyl palmitate, or vitamin A palmitate, is the

ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ar ...

retinol Retinol, also called vitamin A1, is a fat-soluble vitamin in the vitamin A family found in food and used as a dietary supplement. As a supplement it is used to treat and prevent vitamin A deficiency, especially that which results in xerophtha ...

(

vitamin A Vitamin A is a fat-soluble vitamin and an essential nutrient for humans. It is a group of organic compounds that includes retinol, retinal (also known as retinaldehyde), retinoic acid, and several provitamin A carotenoids (most notably bet ...

) 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 Li ...

, 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.

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 The visual cycle is a process in the retina that replenishes the molecule retinal for its use in vision. Retinal is the chromophore of most visual opsins, meaning it captures the photons to begin the phototransduction cascade. When the proton is ...

RPE65 Retinal pigment epithelium-specific 65 kDa protein, also known as retinoid isomerohydrolase, is an enzyme of the vertebrate visual cycle that is encoded in humans by the ''RPE65'' gene. RPE65 is expressed in the retinal pigment epithelium (RPE, a ...

isomerizes the retinyl part to 11-cis-retinal.

Uses

Vitamin A palmitate is a common

vitamin supplement A multivitamin is a preparation intended to serve as a dietary supplement with vitamins, dietary minerals, and other nutritional elements. Such preparations are available in the form of tablets, capsules, pastilles, powders, liquids, or injectab ...

, available in both oral and

injectable An injection (often and usually referred to as a "shot" in US English, a "jab" in UK English, or a "jag" in Scottish English and Scots) is the act of administering a liquid, especially a drug, into a person's body using a needle (usually a hypo ...

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. Nyctalopia (ni ...

, 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 (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 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. Hypervit ...

). Retinyl palmitate is used as an

antioxidant Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricant ...

and a source of

added to low fat

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

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,

, 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 Retinoic acid (used simplified here for all-''trans''-retinoic acid) is a metabolite of vitamin A1 (all-''trans''-retinol) that mediates the functions of vitamin A1 required for growth and development. All-''trans''-retinoic acid is required in ...

(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 Senate Majority Leader since January 20, 2021. A member of the Democratic Party, Schumer is in his fourth Senate term, having held his seat since 1999, and ...

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 headqua ...

concluded that diisopropyl adipate increased 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 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 *''Reforme'' ("Reforms"), initial name of the ...

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