Soy-derived ingredients are most often found in skin care products, usually as genistein, a soy isoflavone. There are good reasons why some moisturizers and night creams include soy isoflavones: they brighten the skin, decrease redness, boost collagen production and improve skin tone. These soy isoflavones are weak phytoestrogens and anti-oxidants.
Soybean Oil is the extracted or expressed oil from the soybean, Glycine Soja. It consists primarily of triglycerides of oleic, linoleic and linolenic, saturated acids and Vitamin E. These ingredients are often listed this way and, if you are allergic to soy, you may have to do some research to find out if these acids are obtained from soy rather than another source.
Vitamin-rich soybean oil has a small molecular structure which enables it to penetrate the epidermis – the top layer of your skin. Soy can actually nestle into the cellular structure and stimulate the synthesis of collagen, elastin, and other proteins. Its properties are important for cell growth and regeneration by reversing abnormal cell formations.
Soy compounds prevent melanin pigments from adhering to skin cells, which is why genistein is used in skin-brightening creams and lotions. It seems to be most effective with hyperpigmentation caused by sun damage. Genistein does not work for melasma, though, because melasma is fueled by estrogen, and genistein is a phytoestrogen.
Soy is not the only anti-oxidant and collagen booster around, though, which is fortunate, since some people are violently allergic to it and should not use anything containing a soy–derived ingredient. For these people, products containing retinols or growth factors may be a better option.