WAIKOLOA, Hawaii -- Natural ingredients in over-the-counter products with proven effectiveness work through tyrosinase inhibition or by curbing melanosome transfer to keratinocytes, according to Dr. Susan C. Taylor (photographed below).
The substances are supported by studies showing evidence of efficacy for skin brightening and improvement in photoaging; however, the studies are often of lesser quality than dermatologists are accustomed to for prescription drugs approved by the Food and Drug Administration, said Dr. Taylor, founding director of the Skin of Color Center at St. Luke's-Roosevelt Hospital Center in New York.
Rest assured, though, that these natural ingredients have known mechanisms of action, are backed by some evidence of improvement in pigmentation, and can be incorporated as adjuncts to more potent standard therapies, Dr. Taylor said.
She discussed several products in detail:
- P Olay Definity. One of the most rigorous scientific evaluations for any of the natural products for skin brightening was conducted by Dr. Alexa B. Kimball of the department of dermatology at Harvard Medical School, Boston, and coworkers.
They conducted a randomized, double-blind trial of Olay Definity (4% niacinamide and 2% N-acetylglucosamine) or its cream vehicle for reduction of facial hyperpigmentation in 202 middle-aged women (Skin & Allergy News, "N-Acetylglucosamine Reduces Hyperpigmentation," December 2006, p. 54).
By all outcome measures, Definity was significantly more effective in reducing the detectable areas of facial spots, as well as hypermelanization and other manifestations of irregular pigmentation, in the Procter & Gamble-funded trial (Br. J. Dermatol. 2010;162:435-41).
- P Arbutin. This glycosylated hydroquinone is derived from cranberry, blueberry, and bearberry leaves, noted Dr. Taylor. In a 50-patient study, the blinded expert consensus was that deoxyarbutin achieved a significant improvement in solar lentigines, but only in the 34 white women (Exp. Dermatol. 2005;14:601-8).
- P Liquiritin. A cream containing liquiritin--a licorice extract derived from the Glycyrrhiza inflata plant of northwest China--was compared with a vehicle in 20 patients with melasma.
Investigators rated 80% of liquiritin-treated areas as showing excellent response in terms of reduced pigment intensity and size, while the other 20% were rated as having a good response. In contrast, no vehicle-treated areas were rated as having a good or excellent response (Int. J. Dermatol. 2000;39:299-302).
- P Soy. Fresh soy, which contains essential fatty acids, saponins, lecithin, and oleic acid, has a salutary effect on hyperpigmentation. Fermented soy contains isoflavones having an estrogenic effect; it is of no value in skin brightening, Dr. Taylor said. Researchers at Johnson & Johnson conducted a double-blind, vehicle-controlled trial of a soy moisturizer in 65 women with moderate facial photoaging. The group treated with the moisturizer showed significantly greater improvement than controls in terms of reduced mottled hyperpigmentation, blotchiness, fine lines, and tactile roughness (J. Drugs Dermatol. 2007;6:512-22).n
Disclosures: Dr. Taylor has served as an investigator, speaker, and/or advisory board member for Allergan, Beiersdorf, Johnson & Johnson, Medicis, Procter & Gamble, Stiefel, and T2 Skin Care. SDEF and this news organization are owned by Elsevier.