Cosmeceuticals - Lotions And Potions: Skin Health

Content provided by the Faculty of the Harvard Medical School

Cosmeceuticals

Some cosmetics contain ingredients, known in the cosmetic industry as cosmeceuticals, that have medicinal or druglike benefits. These agents, which include vitamins, growth factors, and peptides, are found in products prescribed by dermatologists and many others that are available over the counter. The FDA does not recognize the term cosmeceutical but regulates some of the substances and makes recommendations on others. Several cosmeceuticals show promise against skin aging and photoaging. Studies show that they diminish wrinkles and age spots, smooth skin texture, and reduce the yellow hue that comes with age.

Alpha hydroxy acids

AHAs are obtained from various fruits, including grapes, citrus fruits, and apples. Look for them on product labels as glycolic acid, lactic acid, malic acid, hydroxycaprylic acid, alpha-hydroxyoctanoic acid, triple fruit acid, or sugar cane extract. Although the FDA does not regulate AHAs as drugs, it has issued guidelines on their safe use because they can cause skin irritation and increase skin sensitivity to UV rays. The FDA has cautioned consumers only to use products that contain an AHA concentration of 10% or less and a pH of 3.5 or more (lower pH numbers are more acidic), and to use a sunscreen in conjunction with AHA-containing products. AHAs, particularly glycolic acid, are used in chemical peels in concentrations of 20%–30% and higher. An FDA review panel concluded that cosmetologists or skin aestheticians could safely use glycolic acid and lactic acid at concentrations not greater than 30% and with a pH not lower than 3.0 for brief skin care sessions provided that thorough rinsing and daily sun protection follow. In higher concentrations, AHAs are applied by physicians.

Beta hydroxy acids

BHAs, another type of cosmetic exfoliant, are believed to smooth skin without some of the irritating effects of AHAs. The most widely used BHA is salicylic acid, a relative of aspirin. That salicylic acid has anti-inflammatory properties and doesn't penetrate to the dermal layer may explain why it's less irritating than AHAs. Moreover, salicylic acid is more effective than AHAs for exfoliating oily areas of the skin, which makes it useful if you have oily skin or if you're having problems with adult acne.

Salicylic acid and other BHAs can be found in many acne products at effective levels of 1.5%–2%. But antiwrinkle products containing these ingredients tend not to list the percentage on their labels, so it's difficult to know whether they contain sufficient amounts to be effective. Other BHAs include beta hydroxybutanoic acid, tropic acid, and trethocanic acid.

The FDA recommends that you first test BHAs on a small patch of skin to see if irritation occurs, and that you use a sunscreen with BHA products because they can increase the skin's sun sensitivity.

Vitamins and antioxidants

Some of the most confusing questions in skin care concern the use of vitamins and antioxidants (such as vitamins A, C, and E) and ubiquinone (coenzyme Q10). In theory, the use of these substances in moisturizers and other cosmetics makes sense. At the cellular level, antioxidants ward off damage from molecules called free radicals, which cause oxidative deterioration.

Some vitamins and antioxidants are beneficial when applied to the skin. Derivatives of vitamin A are active ingredients in retinoids, drugs that reduce photodamage and increase collagen production (see "Retinoids"). A 10% concentration of vitamin C significantly reduced fine wrinkles, made skin smoother, and improved skin tone and sallow hue in one 12-week clinical trial. Other studies have reported that vitamin C helped repair elastic tissue and increase collagen, and that vitamin B₃ (niacinamide) reduced signs of photoaging as well as the cancer-causing effects of ultraviolet radiation.

Coenzyme Q10, a naturally occurring antioxidant, has also been shown to reduce wrinkles and guard against ultraviolet light damage. A 12-week clinical trial of lipoic acid, another antioxidant, reported a significant decrease in wrinkles, age spots, and roughness. Copper, an antioxidant metal, may play a role in collagen and elastin production.

Some moisturizers and other skin care products contain vitamin E, but no clinical studies have shown that it can prevent or reverse signs of photoaging.

Growth factors

Hundreds of growth factors occur naturally in the human body to help heal wounds by promoting new tissue formation. Several studies have found that creams with different combinations of these substances diminish wrinkles. A study published in Dermatologic Surgery in 2006 compared the effects of two different creams containing growth factors with a third cream that contained vitamin C. After three months, physicians, not knowing which subjects used which cream, found that those who had used the growth factor products had the greatest reduction of wrinkles.

Peptides

These compounds, which have various roles in the body, are used as cosmeceuticals for different effects. Some peptides stimulate the production of collagen and elastin. Others stabilize copper (an antioxidant metal shown to reduce wrinkles), improve skin elasticity, and reverse other signs of photoaging.

Last updated:	July 20, 2007