While skin aging is inevitable, it’s possible to slow the damage, and—according to new research—perhaps even reverse aging that has already occurred.
A decline in estrogen is part of the explanation for skin changes seen with menopause. Estrogen therapy in older women produces increases in collagen—the protein that gives skin its elasticity and resilience—and also increases skin thickness. It’s possible that plant estrogens, like the isoflavones in soyfoods, can have a similar effect. Soy phytoestrogens are not the same as the hormone estrogen but phytoestrogens and estrogen do share some properties in common.
Therapy aimed at improving skin health has focused on a compound called hyaluronic acid (HA). HA exists within the matrix formed by collagen and is responsible for moisturizing the skin, among other functions that keep skin healthy. Researchers in São Paulo, Brazil recruited 30 postmenopausal women between the ages of 45 and 55 to study the effects of soy phytoestrogens on HA (1). Half of the subjects were given a gel containing estrogen and the other half received a gel containing the primary soy phytoestrogen, genistein. Women were instructed to apply the gel to their face every night and advised not to use any other skin care products aside from sunscreen. A facial skin biopsy was taken from the area just in front of the ear at the start of the study and again after 24 weeks.
After 24 weeks, HA concentration in the skin increased markedly in both groups, rising by about 2.5-fold in response to soy and about 4-fold in response to estrogen. Neither estrogen nor phytoestrogens were systematically absorbed through the skin. This study is not the first to show that topical application of soy phytoestrogens improves skin health. Not surprisingly, a number of commercial skin creams now contain soy isoflavones.
But what about improving skin from the inside out? Does soy have a role in this regard as well?
Although there have been relatively few clinical studies on soy isoflavone consumption and skin health, the findings are encouraging. New research, not yet published, has shown that soy phytoestrogens decreased wrinkles and increased collagen synthesis in postmenopausal women after 14 weeks. Although more research is needed, skin health appears to be another advantage of consuming soyfoods.