This antioxidant, antiproliferative, antiangiogenic phytoestrogenic extract is used to treat hyperhidrosis in Asian medicine (22). Epidemiologic studies indicating much lower malignancy and cardiac disease rates in people eating a diet high in soy resulted in thorough investigations revealing multiple medicinal uses. The major components of soy are phospholipids (45-60%) such as phosphatidyl choline and essential fatty oils (30-35%). The minor components include the most active compounds such as isoflavones, saponins, essential amino acids, phytosterols, calcium, potassium, iron, and the proteases soybean trypsin inhibitor and Bowman-Burke inhibitor. The most potent isoflavones are the phytoestrogens genistein and daidzein. Topical estrogens have been shown to increase skin thickness and promote collagen synthesis; thus, soy phytoestrogen stimulatation of human fibroblast collagen synthesis is expected. Genistein, the most potent antioxidant, inhibits lipid peroxidation and chemical – and UVB-induced carcinogenesis. The two protease inhibitors lighten pigmented lesions and reduce unwanted facial and body hair in human clinical trials (3,51,52).
Soy products have rarely caused dermatitis and pruritis as well as asthma and gastrointestinal symptoms (3,22).