Protein, which is made of nitrogen-containing amino acids, is one of the major nutrients used by all the cells of our bodies (Medical Reference 1). Throughout our lives, the protein in our body is being broken down and reformed. The formation of new protein requires both essential (those that our body can’t make) and nonessential amino acids (those that the body can make). Proteins that provide all of the essential amino acids in high enough concentrations are called complete proteins, while those that are low or lacking in one or more of these amino acids are considered to be incomplete proteins. High-quality complete proteins provide the best way to meet human nutritional needs.
Soy is a high-quality, complete protein that provides all the essential amino acids in amounts necessary for our nutritional needs (Medical Reference 2). The addition of soy products that contain high-quality protein to the diet is beneficial for such things as weight loss and reduction of heart disease risk. Per the FDA, consuming 25 grams of soy protein daily, as part of a diet low in saturated fat and cholesterol, may help reduce risk of heart disease.*
Overall, soy is a high-quality protein that provides a full complement of essential amino acids and offers many potential health benefits. Recent reports indicate that skin, hair, and nail health maintenance are among the potential health benefits associated with the consumption of soy products (Medical Reference 3-8).
1. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). The National Academies Press, 2005.
2. Kolar CW, Richert SH, Decker CD, Steinke FH, van der Zanden RJ. “Isolated Soy Protein”, Chapter VIII in “New Protein Foods”, Vol. 5, Seed Storage Proteins, ed. Altschul AA, Wilcke HL, Orlando: Academic Press, 1985.
3. McElwee KJ, Niiyama S, Freyschmidt-Paul P, Wenzel E, Kissling S, Sundberg JP, Hoffman R. Dietary soy oil content and soy-derived phytoestrogen genistein increase resistance to alopecia areata onset in C3H/HeJ mice. Exp Dermatol 2003; 12:30-36.
4. Tsuruki T, Takahata K, Yoshikawa M. A soy-derived immunostimulating peptide inhibits etoposide-induced alopecia in neonatal rats. J Invest Dermatol 2004; 122;848-850.
5. Kim SY, Kim SJ, Lee JY, Kim WG, Park WS, Sim YC, Lee SJ. Protective effects of dietary isoflavones against UV-induced skin-aging in hairless mouse model. J Amer Coll Nutr 2004; 23:157-162.
6. Wei H, Saladi R, Lu Y, Wang Y, Palep SR, Moore J, Phelps R, Shyong E, Lebwohl MG. Isoflavone genistein: photoprotection and clinical implications in dermatology. J Nutr 2003; 133:3811S-3819S.
7. Widyarini S, Spinks N, Husband AJ, Reeve VE. Isoflavonoid components from red clover (Trifolium pratense) protect from inflammation and immune suppression induced by UV radiation. Photochem Photobiol 2001; 74:465-470.
8. Draelos ZD, Blair R, Tabor A. Oral soy supplementation and dermatology. Cosmetic Dermatology 2007; 20:202-204.