Soy-derived ingredients are increasingly 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 phytoestrogens (albeit weak ones) and anti-oxidants, which is why they are popular ingredients in skin care products marketed towards menopausal women.
All this went through my mind this week when I read about a new Japanese study showing that a soy supplement containing S-equol, a compound made from fermented soy beans, appears to improve the appearance of crow’s feet, the wrinkles at the corners of the eyes that most people get sooner or later (a nicer term for them is laugh lines). S-equol is actually made in the human body as a by-product of the digestion of soy, but a fairly large percentage of people lack the necessary intestinal flora to produce it. The post-menopausal women in the study were non-producers of S-equol. According to the study, the participants showed some improvement in their crow’s feet.
While I thought the study showed potential, I am certainly not recommending that people rush out to buy soy supplements. First of all, the study was very small and the results were not conclusive. Second, the researchers acknowledged that improvements were modest. Third, soy supplements are not good for everybody, and may even be harmful if taken in large quantities. Menopausal women who take soy supplements may experience vaginal bleeding, for instance, and some doctors feel that breast cancer patients should limit their soy intake. The American diet is rich enough in soy as it is, anyway, considering how often soy-derived compounds are listed among the ingredients of processed food.
My personal opinion is that soy is probably better used topically. Soy compounds prevent melanin pigments from adhering to skin cells, which is why genistein, the most frequently used soy isoflavone, 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, remember, is a phytoestrogen.
Post menopausal women , whose estrogen production has dropped dramatically, may see the most noticeable results with soy-containing skin care creams, since the soy phytoestrogens work to repair the thinness and decreased collagen production cause by a lack of estrogen.
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, I recommend products containing retinols or growth factors, which in my opinion have even better results than soy.