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The Benefits, Risks, and Uncertainties of Soy for Lower Blood Cholesterol

Soy, a type of legume, can be found in many products. On the grocery store shelves, you will see soy milk, tofu, protein bars, veggie burgers, and many other options. Are you interested in adding soy to your diet? Are there health benefits? Find out if soy is a good option for you.

Soy and Cholesterol Levels


Some studies have found that substituting soy protein for high-fat meats and other foods may slightly reduce LDL (bad) cholesterol levels. Since high cholesterol puts you at an increased risk of developing heart disease, the Food and Drug Administration (FDA) allows a "heart healthy" label on foods that contain 6.25 grams (g) of soy protein. But, researchers do not know the exact components of soy that may lead to these benefits. And some experts are debating if this label is deserved at all.

Soy Safety Issues

While soy is considered safe for most people, there are some health concerns if you have certain conditions, such as:

  • Impaired thyroid function—Soy may affect the thyroid gland, but research had produced conflicting results. In general, if you have problems with your thyroid gland, it is a good idea to avoid eating large amounts of soy.
  • Lower testosterone levels—One study found that soy may decrease testosterone levels in men. This could potentially cause problems with infertility or erectile dysfunction.
  • Problems with absorbing certain nutrients—Soy could reduce how well your body absorbs zinc, iron, and calcium.

If you are concerned about any of these safety issues, talk to your doctor before adding soy to your diet.

Ways to Get More Soy Into Your Diet

Here are some tips on substituting soy protein for meats and other protein sources in your diet:

  • Include it in other dishes:
    • Mash a cake of tofu and use it in place of ricotta cheese in your lasagna, soups, or stews.
    • Mix textured vegetable protein into hamburgers and seasoned meat dishes like tacos, chili, and casseroles.
    • Add cubes of fried, seasoned tofu to salads.
  • Try Asian cuisine—Japanese, Chinese, Thai, and Vietnamese foods often contain flavorful soy options, including tofu, tempeh, and edamame (green soy beans). Edamame is eaten cold and salted. Tofu and tempeh can be stir-fried, steamed, or added to soups.
  • Use supplements and soy protein powders—Try mixing soy protein powders into smoothies or mashed potatoes.
  • Soy nuts, flavored with salt and spices, make a delicious snack.
  • Use soymilk in cereal.
Major Food Sources
Soy FoodServing size Soy content (grams) Isoflavones (milligrams)
Soybeans, cooked½ cup9-1140-50
Soy milk (regular)1 cup710
Soy milk (fortified)1 cup1043
Textured soy protein¼ cup1133
Isolated soy protein½ ounce1127
Tofu½ cup1025
Meat alternatives (soy crumbles)½ cup118.5

RESOURCES:

American Heart Association
http://www.heart.org

National Heart, Lung, and Blood Institute
http://www.nhlbi.nih.gov

CANADIAN RESOURCES:

Dietitians of Canada
http://www.dietitians.ca

Health Canada
http://hc-sc.gc.ca

References:

20 ways to increase soy in your diet. University of California San Francisco Medical Center website. Available at: http://www.ucsfhealth.org/education/20_ways_to_increase_soy_in_your_diet/index.html. Accessed June 11, 2014.

Go Ask Alice: What are the benefits of soy? Columbia University website. Available at: http://goaskalice.columbia.edu/what-are-benefits-soy. Updated November 2011. Accessed June 11, 2014.

Hypercholesterolemia. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated June 3, 2014. Accessed June 11, 2014.

Harland JL, Carr TA. Does a practical daily intake of ~25 g soy protein significantly lower cholesterol?—A meta-analysis of recent studies. J of Nutr. 2004;134(5):1267S (Poster Abstract).

Mackey R, Ekangaki A, Eden JA. The effects of soy protein in women and men with elevated plasma lipids. Biofactors. 2000;12:251-257.

Qin Y, Niu K. Isoflavones for hypercholesterolaemia in adults. Cochrane Database Sys Rev. 2013:6: CD009518.

Rosell MS, Appleby PN, Spencer EA, Key TJ. Soy intake and blood cholesterol concentrations: a cross-sectional study of 1033 pre- and postmenopausal women in the oxford arm of the European Prospective Investigation into Cancer and Nutrition. American J of Clin Nutr. 2004;80(5):1391-1396.

Sacks FM, Lichtenstein A, Van Horn L, Harris W, Kris-Etherton P, Winston M; American Heart Association Nutrition Committee. Soy protein, isoflavones, and cardiovascular health: an American Heart Association Science Advisory for professionals from the Nutrition Committee. Circulation. 2006;113(7):1034-44.

Siegel-Itzkovich J. Health committee warns of potential dangers of soya. BMJ. 2005;331(7511):254.

Soy. EBSCO Natural and Alternative Treatments website. Available at: http://www.ebscohost.com/biomedical-libraries/natural-alternative-treatments. Updated August 22, 2013. Accessed June 11, 2014.



Last reviewed June 2014 by Michael Woods, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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