This Facts About reviews soy and gives examples of foods to choose from as well as foods to avoid. We provide a guide for selecting an appropriate portion size, and recommendations for incorporating healthy changes into your diet.

What are the recommended servings per day?

• 1-2 servings per day

Why choose whole soy foods?

• Low in fat
• Excellent source of fiber
• Good source of enriched calcium
• Excellent source of high quality digestible protein (contains all the amino acids essential to human nutrition)
• Tempeh and tofu are moderately rich in important minerals such as zinc, magnesium, iron and selenium
• Some products, such as miso and soy yogurt, are probiotic (contain bacteria which contribute to the health of the intestinal tract)
• Contains isoflavones, which are converted by bacteria in the intestines into phytoestrogens and are beneficial in reducing risk of various cancers, heart disease and osteoporosis

Selected Food Sources with Serving Sizes

Edamamé (Green Soybeans)

These are large soybeans harvested when the beans are still green and sweet tasting. They are high in protein and fiber and contain no cholesterol.

Miso

A smooth paste, made from soybeans and/or grains such as rice or barley, plus salt and a mold culture, aged in cedar vats for one to three years. Miso is a good source of protein, calcium, and zinc.

Soymilk, Soy Beverages

Soybeans, soaked, ground fine and strained, produce a fluid called soybean milk, which is a good substitute for cow's milk. Soymilk is an excellent source of high quality protein and B-vitamins.

Soynuts

Whole soybeans that have been soaked in water and then baked until browned. Roasted soy nuts are highin protein and isoflavones and are similar in texture and flavor to peanuts.

Soy Yogurt

Made from soymilk, its creamy texture makes it an easy substitute for sour cream, cream cheese or dairy yogurt. Soy yogurt is high in protein and calcium.

Tempeh

Whole soybeans, sometimes mixed with another grain such as rice or millet, are fermented into a rich cake of soybeans with a smoky or nutty flavor. Tempeh is a good source of protein and calcium.

Tofu & Tofu Products

Known as soybean curd, tofu is a soft cheese-like food made by curdling fresh hot soymilk with a coagulant. It is a neutral-flavored product that easily absorbs the flavors of other ingredients with which it is cooked. Tofu is rich in high-quality protein and B-vitamins and is low in sodium.

Selected Food Sources of Whole Soy

Specific Considerations

Breast Cancer

• Soy isoflavones are phytoestrogens that can act in the body in similar ways as estrogens
• High levels of soy isoflavones may raise the risk of breast cancer in post-menopausal women. We do not recommend isolated soy in the form of soy supplements or powders; instead we recommend eating whole soy foods such as soybeans.
• Tofu, tempeh, edamame, miso, and other whole soy foods contain isoflavones in combination with protein, fiber, and some fat
• Phytoestrogens in soy may protect estrogen receptors from excessive stimulation by the body's own hormones and foreign estrogen-like substances
• Benefits of whole soy foods seem to outweigh the risks for most people
• Because of the controversy over soy, especially as it relates to breast cancer, we recommend that you discuss this with your physician before deciding whether including soy foods in your diet is right for you

Sensitivity /Allergy to Soy

Food allergies are abnormal responses of the body’s immune system to certain foods or ingredients. They can show up as rashes, swelling of the skin, nasal congestion, nausea and diarrhea or the most serious reaction – anaphylactic shock, which is life threatening. People with food allergies usually need to eliminate the problem foods from their diet altogether.

• Soy is a common source of food sensitivity
• Soy allergy is more common in infants; adults may suffer from soy allergy but it is rare
• The average age at which the allergy manifests is 3 months
• The majority of infants outgrow it by the age of two
• We recommend reading all ingredient labels and if in doubt, contact the manufacturer of the product before purchase about soy sensitivity

Pesticide Use

Pesticides are chemicals that are used to control pests that destroy crops. They are used in the production of most crops sold in the United States. These chemicals may increase your risk for cancer or other chronic diseases and should be limited in your diet.

Choose Organic

We recommend organic foods because they contain less pesticide residue. We believe they also provide better flavor and are a better nutritional choice than conventionally grown.

Organic food is produced by farmers who emphasize the use of renewable resources and the conservation of soil and water to enhance environmental quality for future generations. Organic food is produced without using most conventional pesticides, petroleum-based fertilizers, or sewage sludge-based fertilizers, bio-engineering, or ionizing radiation. Organic systems replenish and maintain soil fertility, eliminate the use of toxic and persistent pesticides and fertilizers, and build biologically diverse agriculture.

Ideas to increase soy consumption

1. Choose whole soy foods, such as miso, tempeh, tofu, soybeans, soynuts, and soy milk, over isolated soy products and supplements.
2. Avoid heavily-processed soy ingredients such as soy protein isolate, soy protein concentrate, hydrolyzed soy protein, and texturized soy protein.
3. To learn how to cook with soy foods, ask a friend for recipes, search the internet, or locate soy cookbooks.
4. Edamamé is usually located in the frozen section of the supermarket, and are available either in the pod or shelled.  They cook quickly and can be eaten cold or warm, but don’t eat the pod!
5. Miso is a main ingredient of miso soup, a traditional Japanese soup available in restaurants and in many grocery stores.
6. Soybeans can be used like dried and canned beans in soups, salsas and other dishes containing beans.
7. Soymilk can be used in place of cow’s milk in cooking, baking and drinking.  Try adding some to a smoothie or to soups or sauces.  Soymilk comes in non-refrigerated aseptic boxes found on grocery shelves or refrigerated in plastic containers in the dairy section.
8. Roasted soy nuts are available in most grocery stores and are great for snacking on or adding to trail mix.
9. Soy yogurt is a great substitute for dairy yogurt and is available in the refrigerated section of most grocery stores.
10. Tempeh is sold in vacuum packed rectangle cakes/patties and can be used in place of meat in stir fries.
11. Tofu is found in water packed tubs in the refrigerated section or on grocery shelves in aseptic packages.  Uses for tofu are endless:
    • Silken tofu, which is smooth and creamy, can be used in place of cream in soups or as a substitute for mayonnaise or sour cream in salad dressings and dip.
    • Soft tofu is moist and more firm than silken tofu and can be substituted for soft cheese like ricotta in your favorite Italian dish.
    • Firm and extra firm tofu will hold its texture and shape and can be used in place of meat in salads, grilled shish-ka-bobs or a fajita dish.

This Facts About document is published by Monica Myklebust, MD, and Jenna Wunder, MPH, RD, at University of Michigan Integrative Medicine Clinical Services. Our mission is to care for people using an Integrative Medicine model that reaffirms the importance of relationship between practitioner and patient, focuses on the whole person, is informed by evidence, and makes use of all appropriate therapeutic approaches to achieve optimal health and healing.

Resources

Allergies:  Living with a Soy Allergy
Web MD Website
www.webmd.com
Accessed May 2, 2006

Isoflavones:  New Frontier in Nutrition
Patterson, Anne       
US Soyfoods Directory
www.soyfoods.com
Accessed May 2, 2006

Jury Still Out on Soy and Health
Boyles, Salynn          
Web MD Website
www.webmd.com
Accessed May 2, 2006

Soy and Menopausal Symptoms
Stokes, Monica
Thomson American Health Consultants
www.ahcpub.com
Accessed May 2, 2006

Soy:  Health Claims for Soy Protein, Questions about Other Components
Henkel, John
FDA Consumer Magazine May-June 2000
www.fda.gov
Accessed May 2, 2006

USDA-Iowa State University Database on the Isoflavone Content of Foods-1999
USDA Nutrient Data Laboratory
www.nal.usda.gov/fnic/foodcomp/Data/isoflav/isfl_tbl.pdf
Accessed May 2, 2006

Original Research and Review Articles

Barnes S, et al.  Rationale for the use of genistein-containing soy matrices in chemoprevention trials for breast and prostate cancer.  Journal of Cellular Biochemistry.  1995;22:181S-187S.

Bhathena SJ, et al.  Beneficial role of dietary phytoestrogens in obesity and diabetes.  American Journal of Clinical Nutrition.  2002;76:1191-1201.

Hasler CM.  The cardiovascular effects of soy products.  The Journal of Cardiovascular Nursing.  2002;16:50-63.

Kimoto H, et al.  Identification and probiotic characteristics of lactococcus strains from plant materials.  Japan Agricultural Research Quarterly.  2004;38:111-117.

Messina MJ, et al.  Soy for breast cancer survivors:  a critical review of the literature.  Journal of Nutrition.  2001;131:3095S-3108S.

Messina MJ  Legumes and soybeans: overview of their nutritional profiles and health effects.  American Journal of Clinical Nutrition. 1999;70:439S-450S.

Sacks FM, et al.  Soy protein, isoflavones, and cardiovascular health.  Circulation.  2006;113:1-11.