Aging baby boomers have shown an increasing interest in maintaining a youthful exterior. As a result of this, a corresponding increase in topical antiaging formulations (creams, ointments, cleansers) also known as cosmeceuticals has been seen. These products come with a seemingly limitless number of key active ingredients and claims of reducing the signs of aging and/or maintaining a youthful appearance.
The term cosmeceutical was introduced by Albert Kligman in 1984, referring to substances that claim to have both cosmetic and therapeutic effect. Many contain biologically active ingredients, and in general, but claims of efficacy are largely unproven in scientific trials. There is limited research being done on cosmeceuticals in academic dermatology, with most of the large studies coming from industry sponsored studies which taints the results with potential bias.
Although some product claims for the active ingredients used in cosmeceutical formulations are evidence-based, people often place their confidence in the claims made by the product. Without testing the actual product, it is possible that at inadequate concentrations or ineffective formulations are present, and any beneficial effect will become nullified.
Some Common Types of Cosmeceutical Ingredients
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Alpha Hydroxy Acids (AHAs)
Also referred to as fruit acids, they are a common ingredient found in cosmeceutical products. Examples include:
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AHAs improve skin texture and reduce the signs of aging by promoting cell shedding in the outer layers of the skin and by restoring hydration. They tend to promote cell growth and slow cell differentiation, thus giving rise to younger looking skin.
Antioxidants
Antioxidants reduce free-radical damage, thereby preventing damage to cellular molecules, inhibiting inflammation, and protecting against photodamage and skin cancer. Common antioxidants include alpha-lipoic acid (ALA), L-ascorbic acid (vitamin C), niacinamide (vitamin B3), N-acetyl-glucosamine (NAG), α-tocopherol, and ubiquinone (CoQ10).
Alpha-lipoic acid has anti-inflammatory properties and acts as an exfoliant.
L-ascorbic Acid (Vitamin C) improves fine lines and reduces both pigmentation and inflammation. However many of formulations are not effective on the skin.
Niacinamide is a potent antioxidant that is generally well tolerated. Studies have revealed significant reduction in fine lines and wrinkles, hyperpigmented spots, red blotchiness, and skin sallowness, as well as improved skin elasticity.
N-acetyl-glucosamine (NAG). NAG is a more stable form of glucosamine, and may prevent new signs of photodamage from occurring, and fade existing imperfections by interrupting the chemical signals that promote melanin production.
α-tocopherol (Vitamin E). When taken orally, α-tocopherol protects membrane lipids from peroxidation. As a component in topical formulations, it, like unmodified L-ascorbic acid, has shown some limited efficacy.
Ubiquinone (CoQ10). Ubiquinone is a naturally occurring, fat-soluble antioxidant and there is good in vitro evidence that it can suppress fibroblast production of UVA-induced collagenase, thereby reducing collagen breakdown. It is an effective antioxidant protecting the dermal matrix from both intrinsic and extrinsic aging.
Botanicals
Botanicals comprise the largest category of cosmeceutical additives found in the marketplace today. Their use is unregulated and often unsupported by science and their purported therapeutic properties remain largely unexplored.
Green Tea Extract. Research has shown that green tea (Cammelia sinensis) polyphenols are potent suppressors of carcinogenic activity from UV radiation and can exert broad protection against other UV-mediated responses, such as sunburn, immunosuppression, and photoaging.
Ferulic Acid. This compound, which is derived from plants, is considered to be a potent antioxidant, and has been shown to provide photoprotection to skin.
Grape Seed Extract. This botanical has been established as a potent antioxidant and has been shown to speed wound contraction and closure.
Depigmenting Agents
Skin-lightening agents added to product formulations have become increasingly popular. Common depigmenting ingredients include hydroquinone, ascorbic acid (vitamin C), kojic acid, and licorice extract (glabridin).
Hydroquinone. Hydroquinone has been the agent of choice for skin lightening. The US FDA has proposed concentrations between 1.5% and 2% in skin lighteners to avoid potential negative effects of this chemical.
Ascorbic Acid (Vitamin C). Ascorbic acid is a naturally occurring antioxidant found in citrus fruits and leafy green vegetables. It is hydrophilic, so skin penetration is low.
Kojic Acid. Kojic acid is a less commonly used bleaching agent. When combined with dipalmitate, there is improved skin penetration and greater stability, but there is little research to support its efficacy.[27]
Licorice Extract (Glabridin). Several studies on melasma have shown good efficacy with only mild irritation that disappeared with discontinuation.[25]
Exfoliants
Exfoliants promote skin turnover by removing adherent cells in the outer skin layer. Common exfoliants found in cosmeceutical preparations include salicylic acid (SA), lactic acid, and glycolic acid. There are concerns that repeated use of SA and AHAs could cause the dermis and epidermis to be more vulnerable to penetration by UV radiation. Therefore, patients should be advised to use adequate sun protection.
Moisturizers
Moisturizers restore water content to the outer skin layer, and provide a soothing protective film. They improve the appearance and tactile properties of dry and aging skin, restore the normal barrier function of the skin, and reduce the release of inflammatory cytokines. Moisturizers comprise an important therapeutic component in the management of various skin conditions
Topical Peptides
Topical peptides are regarded as cellular messengers that are formed from amino acids and are designed to mimic peptide fragments with endogenous biologic activity. Improvements in wrinkle appearance and length can be seen
Retinoids
Retinoids are among the most common ingredients found in cosmeceuticals. In fact, they are the most studied and have the most data behind them. They consist of natural and synthetic derivatives of vitamin A that reduce hyperpigmentation and inhibit enzymes from breaking down collagen.
Retinoic Acid (Tretinoin). There is extensive literature on the use of tretinoin, which is considered to be one of the most potent compounds for treating the signs of aging and/or photodamaged skin, including fine lines, hyperpigmented spots, and wrinkles.
Retinol (Vitamin A). Retinol is oxidized into retinaldehyde and then into retinoic acid, the biologically active form of vitamin A. Topical retinol has only a modest retinoid-like biologic activity compared with topical retinaldehyde and retinoic acid.
Retinaldehyde. Retinaldehyde is viewed in a large part as an intermediate form during the conversion of retinol to retinoic acid.
Sunscreens
Sunscreens are the single most important cosmeceutical, because they protect skin against solar radiation, which is the most important damaging environmental agent. As a result, they help to prevent the signs of aging. Sunscreens contain active ingredients that act as ultraviolet filters. The recommended application is 2mg/cm2, though this is rarely achieved in real-life practice.
from Skin Therapy Lett. 2008;13(8):n/a. ©2008 SkinCareGuide.com
Martin Jugenburg,MD, FRCSC
Toronto, ON
