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Quest Vitamins LTD,
8 Venture Way,
Aston Science Park,
B7 4AP.

Tel: 0121 359 0056
Fax: 0121 359 0313
Registered in England No. 2530437

Soy Protein


The soybean has long been valued in Asia as a high-protein food rich in nutrients. Due to its apparent ability to reduce cholesterol levels, soy protein products are allowed to carry the FDA approved "heart healthy" label. Soy protein also contains isoflavonones, which may reduce the risk of breast and uterine cancer as well as prevent Osteoporosis.


25 g of soy protein per day to reduce cholesterol. This is the equivalent of about 2 cups of soymilk or pound of tofu.


Soy protein has been documented to reduce blood cholesterol levels, as well as improve the ratio of LDL to HDL cholesterol (1).

While it is not well established, soy protein may help reduce the risk of breast and uterine cancer. Isoflavonones may be responsible for this effect (2,3).

Menopausal symptoms:
Soy protein may also reduce "Hot Flushes," a common menopausal symptom (4).


Soy protein is believed to be quite safe. However, isoflavonones may be harmful in certain situations. For instance, isoflavonones may not be safe for women who have already had breast cancer.


Isoflavonones may interact with hormonal medications such as estrogen, tamoxifen, or raloxifene. In addition, they may interfere with the absorption of Zinc, Iron, and Calcium supplements (5,6,7).

Food sources of soy protein include tofu, plain soybeans, soy cheese, soy burgers, soymilk, and tempeh. Soy protein supplements are also available.


1. Anderson JW, et al. Meta-analysis of the effects of soy protein intake on serum lipids. N Engl J Med 33: 276-282, 1995.
2. Goodman MT, et al. Association of soy and fiber consumption with the risk of endometrial cancer. Am J Epidemiol 146: 294-306, 1997.
3. Messina MJ, Persky V, Setchell KDR, and Barnes S. Soy intake and cancer risks: a review of the in vitro and in vivo data. Nutr Cancer 21: 113-131, 1994.
4. Albertazzi P, Pansini F, Bonaccorsi G, et al. The effect of dietary soy supplementation on hot flashes. Obstet Gynecol 91: 6-11, 1998.
5. Werbach M. Foundations of nutritional medicine. Tarzana, CA: Third Line Press, 1997: 202.
6. Hallberg L, et al. Phytates and the inhibitory effects of bran on Iron absorption in man. Am J Clin Nutr 45: 988-996, 1987.
7. Heaney RP, et al. Soybean phytate content effects on Calcium absorption. Am J Clin Nutr 53: 745-747, 1991.