Tokyo

Beauty spots: the skin of Asian and Caucasian women differs in its sensitivity to the Sun's ultraviolet rays. Credit: T. AIZAWA/REUTERS/NEWSCOM

Cosmetics companies and scientists around the globe are expanding their efforts to understand Asian skin problems, a symposium was told earlier this month.

Many skin treatments have been developed for Caucasian women, but women in east Asia have different skin problems, say specialists. These include dark melanin spots, which result mainly from exposure to the Sun's ultraviolet rays.

On 11 December, 16 researchers from France and several Asian countries addressed a symposium in Paris organized by Moët Hennessy Louis Vuitton (LVMH), a Paris-based company specializing in luxury brands, including cosmetics. The researchers described their latest findings on skin ageing, the skin's reaction to stress, and those melanin spots.

“In the past, researchers just tried to get rid of spots that appeared on the skin,” says Hachiro Tagami, a dermatologist at Japan's Tohoku University in Sendai. “But now they are trying to find out why spots develop.”

In general, researchers say, dark spots appear when the activity of melanocytes is disrupted, usually by excessive exposure to ultraviolet light. Melanocytes are cells that produce the pigment melanin, and their activity levels help to determine the skin's condition, as well as its colour.

Asian women find that melanin pigments develop in their facial skin at earlier ages than they occur in Caucasian women, say researchers, and that the activity of their melanocytes seems to be more sensitive to stress. But Asian skin retains more of its tension and is less likely to wrinkle. Researchers are now gaining insight into the genetic and biochemical differences that might explain these contrasts.

In a collaboration with Bordeaux University, for example, workers at LVMH have come up with new data in the search to explain melanin spot formation. Beneath such spots, the melanocytes, which are usually found in the epidermis, seem to sink into the dermis by disrupting the thin structure between the layers known as the dermo-epidermal junction (M. Cario-Andre et al. J. Cutan. Pathol. 31, 441–447; 2004).

LVMH says it is developing these findings to launch a skincare range for east Asia under its Christian Dior brand. Meanwhile, cosmetics researchers at Procter & Gamble claim to have found a method of controlling the transfer of melanin from melanocytes, using a substance called niacinamide. (T. Hakozaki et al. Br. J. Dermatol. 147, 20–31; 2002).

Regulators will be keeping a close eye on the safety of these skin treatments, however. Last year, Japan's health ministry ordered 12 Japanese and foreign cosmetics companies to stop selling products containing kojic acid, which is believed to reduce melanin levels in the skin. The agent's cosmetic use was approved in 1988, but animal tests have raised fears that it may cause cancer.