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Research Suggests Soy Isoflavones May Help Promote Skin Health

Since ancient times, women across nations and cultures have looked for botanical skin care treatments to reduce the effects of aging. According to traditional Chinese folklore, women working in the tofu industry had the most beautiful skin. Today, many women—and men—desire youthful-looking skin and are looking for ways, including diet, to lessen the visible effects of aging.
Worldwide sales in the cosmetics industry have been reported at an estimated $170 billion USD annually, with skin care products accounting for the largest segment of sales. Now it appears that the benefits of soy go beyond the well-recognized moisturizing and topical applications. Recently-published research strongly suggests that the isoflavones in soy may be an important ingredient for reducing the effects of skin aging. Increasingly, attention is being paid to how the food we eat affects our skin—it is the beauty within concept. According to Yale University School of Medicine researchers, “Diet is a very important factor affecting skin health and wrinkles.”
Clinical evidence increasingly supports the notion that isoflavones favorably impact skin. The most recent study supporting this notion, which was published in the International Journal of Cosmetic Science, found a statistically significant reduction in wrinkles in postmenopausal women in response to an active treatment that included just 25 mg of isoflavones—an amount provided by approximately one serving of traditional soyfoods. This amount is well within the range consumed by older people in Japan—and is an amount that can easily be incorporated into the diet.
It has been observed that wrinkling in Asians is not noticeable until age 50, and that even then its degree is not as marked as in the Caucasian population. Now those observations are bolstered by scientific evidence. The aforementioned randomized double-blind study showed that isoflavones, when part of a beverage of bioactive ingredients, lead to a reduction in wrinkles in postmenopausal women.
In this 14-week study, women were assigned to one of three groups—a control group, or one of two groups receiving a beverage containing a mixture of bioactive compounds including isoflavones. Results show that the two test groups experienced a reduction in the severity of skin roughness compared with the placebo group. In particular, there was a change in the parameter considered the primary indicator of wrinkle depth. The average wrinkle reduction was 10 percent, and there was a positive correlation between baseline wrinkles and the response to the active beverage. That is, the greater the wrinkle depth at baseline, the greater the improvement.
While the results of this one study may not be sufficient for reaching definitive conclusions, they add to existing data on both topical application and ingestion of soy isoflavones in the prevention of skin aging. A Wake Forest University researcher who has conducted work in this area concluded, “Oral soy supplementation has a role in dermatology for postmenopausal women.”
As part of its public education initiative, USSEC publicizes soy-related research and highlights the work of experts conducting studies on the health effects of eating soyfoods. Interest in the effects of isoflavones on overall skin health is not surprising, given that isoflavones bind to estrogen receptors, which are present in the skin. Estrogen therapy is thought to improve skin elasticity, water-holding capacity, pigmentation and vascularity. Estrogens also influence hair follicles.
Another recent study evaluating the effects of isoflavones on skin health involved two groups of 20 healthy postmenopausal women aged 50 to 65 years who consumed for three months their usual diet with or without 20 grams per day of an isoflavone-rich soy protein. Women in the isoflavone group demonstrated statistically significant improvements in facial skin wrinkling, discoloration and overall appearance.
Mark Messina, PhD, MS, Executive Director of the Soy Nutrition Institute points out that several questions regarding isoflavones and skin health still need to be addressed. “At what point does the reduction in wrinkles in response to isoflavones plateau? And, will long-term use permanently slow the development of wrinkles that normally accompanies aging? The answers to these questions will help solidify the precise role of isoflavones and soyfoods on aging skin.” Meanwhile, when considering the totality of the clinical evidence, a strong case can be made that isoflavones are important contributors to skin health.