Retinyl Palmitate - The Dermatology Review

Retinyl Palmitate

ARTICLE

09.28.18 AD DISCLOSURE

Retinyl palmitate is a type of retinoid that is used in skin care products due to its ability to improve signs of aging, hyperpigmentation, and acne.

Origin

The retinoids are a class of chemical compounds that demonstrate vitamin A activity. Retinyl palmitate is the ester of retinol (another name for vitamin A) and palmitic acid, a saturated fatty acid.

Vitamin A cannot be synthesized by the body, which means it must be supplied to the body through dietary sources. Retinoids are required for many different biological processes. In particular, they are involved in embryogenesis, reproduction, vision, growth, inflammation, differentiation, proliferation, and apoptosis. Retinoids are found in the keratinocytes (skin cells) in two forms, retinol and retinyl esters, where they function as antioxidants.

Functions

As a class, retinoids are well-known to be one of the most powerful topically applied ingredients to address the signs of aging and improve acne symptoms. In addition to retinyl palmitate, the retinoid family consists of retinol, retinaldehyde, and retinoic acid, as well as a large number of synthetic derivatives. But did you know that of all the retinoids only retinoic acid has a direct biological effect on the skin? While retinoic acid is available as a topical prescription treatment (tretinoin, brand name Retin-A), it often causes skin irritation including excessive peeling, redness, and photosensitivity which limits its use.

So if retinoic acid is is the only biologically active retinoid, why do cosmetic manufacturers even use retinyl palmitate? Fortunately, our skin has naturally occurring enzymes that can convert retinyl palmitate to its active form. Retinyl palmitate is first converted to retinaldehyde. Then, the metabolism of retinaldehyde to retinoic acid occurs only by keratinocytes at a pertinent stage of differentiation, leading to a more controlled delivery of retinoic acid and weaker retinoid associated adverse effects as compared to tretinoin and other synthetic retinoids. For the remainder of the article, the benefits provided by retinyl palmitate will also apply to all topical retinoids since they are all converted to retinoic acid.

Retinyl palmitate improves the appearance of skin through several mechanisms. One is through the inhibition of collagenase, which is an enzyme that breaks down collagen. By preventing collagen degradation, skin appears more firm and lines/wrinkles will be diminished.

Retinyl palmitate also initiates the increase of epidermal proliferation, which means it produces rapid skin growth. The skin normally takes about 28 days from first formation of a cell in the basal layer of the epidermis until it naturally sheds off. Retinyl palmitate speeds this process up to 14 to 16 days, which results in thicker and more plump skin.

Additionally, retinoids exfoliate the skin by causing more rapid shedding of the stratum corneum. The stratum corneum is typically composed of 14 layers of densely packed corneocytes (dead skin cells). The use of topical retinyl palmitate sloughs off several of these cell layers, thinning the stratum corneum to eight or nine layers of more loosely woven skin cells.

The combination of rapid regeneration of cells and exfoliation of the stratum corneum not only improves the appearance of aging skin, but also helps to peel away dark spots and blemishes. Over time these actions improve acne, soften the skin, lift dark spots and reduce the appearance of wrinkles.

Lastly, retinyl palmitate functions as an antioxidant to limit oxidative damage caused by free radicals. Free radicals are derived from both internal sources (i.e. peroxisomes, phagocytic cells, etc.) and external sources (UV radiation, pollution, alcohol, tobacco smoke, heavy metals, pesticides, etc.) Free radicals are dangerous because they are highly reactive molecules and can damage important cellular structures, like DNA, proteins, carbohydrates, or the cell membrane. Altogether, the damage to cells caused by free radicals is known as oxidative stress. The free radical theory of aging (FRTA) states that organisms age because cells accumulate oxidative stress caused by free radical damage over time. Topical application of retinyl palmitate helps to protect the skin from damage by free radicals.

Safety

The United States Food and Drug Administration has approved the use of retinyl palmitate for several over-the-counter (OTC) products.

The safety of topical retinoids (including retinyl palmitate) has been assessed on several occasions by the Cosmetic Ingredient Review (CIR) Expert Panel. In 1987, the Panel evaluated available scientific data and concluded that they were safe as cosmetic ingredients. In 2005, the Panel considered available new data and reaffirmed the above conclusion. Once again, in 2013, the CIR Expert Panel looked at additional new data and decided the data were not sufficient to re-open the safety assessment. The ‘safe as used’ conclusion in previous reports was confirmed.

References: Wikipedia, “Retinyl palmitate”, International Dermal Institute, “A New Generation of Retinoids”, Clin Interv Aging. 2006 Dec; 1(4): 327–348, Indian J Clin Biochem. 2015 Jan; 30(1): 11–26, Journal of Cosmetic Dermatology, 15, 49–57.

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