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The Facts About Soy

Robin Gammon, RD, LD, Extension Associate, University of Missouri Extension and Jessica Kovarik, RD, LD, Extension Associate, University of Missouri Extension


In 1999, the Food and Drug Administration approved a new health claim for soy protein, stating “Diets low in saturated fat and cholesterol that include 25 grams of soy protein a day may reduce the risk of heart disease.” All soy products containing 6.25 grams of soy protein per serving that are low in fat, cholesterol and sodium may use this health claim.


Since this health claim for reducing heart disease was released, soy protein has also been linked to decreasing the risk of other diseases and health conditions. Soy contains plant-like estrogens called isoflavones, or phytoestrogens, which have been thought to help reduce symptoms of menopause and reducing the risk of breast cancer in women by acting like estrogen in the body. However, a 2006 study by the American Heart Association (AHA) suggests soy may not have as many health benefits as once thought.


The study found that soy protein may lower LDL cholesterol only by 1-3%, which is notably less than the 13% drop of LDL cholesterol that was found in a previous study. Also a specific isoflavone, genistein, has been thought to lead to an increased risk of recurrent breast cancer. Thus far, no research has been conclusive as to the effects soy has on either menopause or breast cancer. So why eat soy?


Soy contains heart-healthy omega-3 fatty acids and cholesterol-removing soluble fiber. In addition, soy protein is lower in saturated fat and higher in polyunsaturated fats (the “good” fats), fiber, vitamins and minerals than animal protein choices.


In fact, eating soy products in place of foods high in saturated fat and cholesterol, such as hamburgers, hotdogs and cheese, can be a part of a low-fat, low-cholesterol diet. By substituting soy foods for your usual choices, even once in awhile, you can lower the amount of calories, fat and cholesterol you eat.


If you want to try soy foods, do so in moderation. Aim for the FDA recommendation of 25 grams of soy protein a day, which is approximately four cups of soy milk.


Looking for ways to enjoy soy? Soy milk is a common soy product and is great in smoothies. Also try a handful of soy nuts for a crunchy snack, soy crisps, tofu, tempeh, soy cheese, miso and soy burgers. If you’re not sure how to prepare a soy food, first check the food package. Many foods have serving tips, cooking suggestions and recipes right on the package.


Despite mixed findings about breast cancer and menopausal symptoms, soy protein may provide cardiovascular benefits when substituted for foods that are high in cholesterol and saturated fats. Therefore, the FDA approved soy protein health claim remains valid and is accepted among most health professionals. The next time you enjoy soy, look for the soy heart health claim and know you’re helping your heart.





  1. Anderson, J., Johnstone, B., & Cook-Newell, M. (1995). Meta-analysis of the effects of soy protein intake on serum lipids [Electronic version]. New England Journal of Medicine, 333, 276-282.
  2. Petrakis, N., Barnes, S., King, E., Lowenstein, J., Wiencke, J., Lee, M., et al. (1996). Stimulatory influence of soy protein isolate on breast section in pre- and post menopausal women [Electronic version]. Cancer Epidemiology Biomarker and Prevention. 5, 785-794.
  3. Sacks, F., Lichtenstein, A., Van Horn, L., Harris, W., Kris-Etherton, P., & Winton, M. (2006) Soy protein, isoflavones, and cardiovascular health: an American Heart Association science advisory for professionals from the nutrition committee [Electronic version]. Circulation, 113, 1034-1044.



Last update: Tuesday, May 05, 2009








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