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Soy extract first became popular in skin care in 2004, when Johnson and Johnson purchased rights to the ingredient from the AMBI brand. Since that time, many companies have jumped on the soy extract bandwagon, adding the ingredient to their formulations. However, is the ingredient safe and effective?
What are some benefits to using skin care products with soy extract?
According to Johnson & Johnson, soy contains small proteins, soybean trypsin inhibitor (STI), Bowman-Birk inhibitor (BBI), amino acids, essential fatty acids, isoflavones, lecithins, mono- and polyunsaturated fatty acids, saponins, phytosterols, phytic acid, minerals and vitamins. According to Paula Begoun, author of Don’t Go to the Cosmetics Counter Without Me, one isoflavone contained in soy is genistein, which has been shown in independent research studies to exhibit both anti-inflammatory and antioxidant properties, and to stimulate the production of collagen and hyaluronic acid in human fibroblasts cultured in vitro, which together increase the firmness, elasticity, and suppleness of skin. These findings have been affirmed in this 2005 study in the journal of Photochemistry and Photobiology, which further reported that use of soy extract twice daily for two weeks reduced the number of hair follicles (dermal papillae) on the skin. Finally, it has been reported in this 2000 study in the journal Dermatology that human trials demonstrate lightening of hyperpigmentation after use of soybean extract for two weeks.
Are there any problems with using soy extract in skin care products?
Many women experience a darkening of the skin during pregnancy (”the mask of pregnancy”) that is caused by overactive melanin production. According to BabyCenter.com, some soy-containing products have estrogenic effects, which can make this form of melasma (darkening of the skin) worse. However, products by Johnson & Johnson brands (i.e., Neutrogena, Aveeno, amongst others) contain a form of soy known as “active soy,” in which the estrogenic compounds have been extracted, so these should not exacerbate melasma like other products.
Does soy in food help improve the skin?
Although the research is limited, this 2004 study from the Journal of the American College of Nutrition demonstrates that mice who were fed soy extract containing isoflavones and subjected to UV light had increased collagen production and decreased matrix metalloproteinase formation (i.e., collagen-digesting enzyme formation) than mice who were not fed soy extract and subjected to UV light. This indicates that soy may have protective anti-aging effects.
Soy is found in foods like (surprise!) soy milk, soy flour, soy sauce and tofu. However, estrogenic compounds have not been extracted from soy. For instance, it was reported in this 2002 study in Nutrition and Cancer that male rats consuming soy isoflavones had lowered testosterone levels. Soy is often considered to be a health food because anti-carcinogenic and cholesterol-lowering effects have been speculated. However, several reports speculate that soy consumption may also lead to disrupted thyroid function. On the contrary, this study in the Journal of Endocrinology and Metabolism reported that the changes in hormonal levels, including thyroid hormone, from soy consumption are modest at best.
Overall, how does soy measure up against other skin care ingredients?
Soy extract with isoflavones acts as an antioxidant that fights hyperpigmentation, decreases hair production, increases collagen and hyaluronic acid production, and has low rates of contact dermal sensitization (irritation) in comparison with 0.15% retinol formulations.
In comparison with retinoids, which do all of the above except decreasing hair production, soy extract has less substantiative research backing its effects, and cannot erase wrinkles and fine lines like retinoids. However, if skin sensitivity or hair production on the face is a problem, soy extract may be desired anyway.
In comparison with niacinamide, which has been found to reduce fine lines and wrinkles, hyperpigmented spots, red blotchiness, and skin sallowness (yellowing), and to increase skin’s elasticity, soy extract again does not erase fine lines and wrinkles like niacinamide can. However, if hair production on the face is a problem, soy extract may be desired instead anyway.
As a result, soy extract overall is an excellent ingredient, particularly if you want to reduce the number of hair follicles on your face. However, due to the estrogenic compounds found in many forms of soy extract, the “active soy” found in Johnson and Johnson products (like Aveeno Active Naturals Ultra Calming Lotion with SPF 15, $17.99, Amazon.com) is probably your best bet. Happy shopping!