Potent antioxidant and anti-inflammatory agent for skin, Soy is one of many phyto (i.e., plant) chemicals that are biologically active against free radicals. Polyphenol compounds, such as the catechins found in green tea, also fit this profile.

Soy extract’s increased use in anti-aging products is largely due to studies showing that genistein (a component of soy) has a collagen-stimulating effect and that various compounds in soy influence skin thickness and elasticity. Researchers have also looked at Bifidobacterium-fermented soy milk extracts. On mouse skin and in human skin fibroblasts (lab cultured), this bacteria-modified form of soy was shown to stimulate production of hyaluronic acid in skin. This was due to the amount of genistein released during the fermentation process.