Efficacy of Soy Isoflavones
Preclinical Studies Using Soy
Soymilk and soybean extract reduces pigmentation in dark-skinned Yucatan pigs treated for 8 weeks. The data suggest that STI and BBI inhibit PAR-2 activation, reduce keratinocyte phagocytosis, thus inducing a reduction in skin pigmentation. Soymilk also contains trace amounts of free fatty acids and their acyl CoA esters that can inhibit trypsin and may participate in PAR-2 inhibition, thus inducing skin lightening. In addition, soybeans contain isoflavones, which are antioxidants that may downregulate tyrosinase’s DOPA oxidase activity.