Soy Protein and Soy Isoflavones

Soy foods are popular because of the many health benefits they provide.
Soy Protein and Soy Isoflavones - Articles
Soy Protein and Soy Isoflavones

Photo credit: Mc559, Flickr User, Creative Commons

Soy is one of the most versatile foods available, as well as one of the most researched in terms of its potential health benefits. To have a better understanding of this common food and ingredient, let’s look at what we know at this time.

Nutrition Information

Soybeans are a legume, meaning their seeds grow in enclosed pods. What makes them unique from other legumes is their high protein, healthy fat and fiber content, and lower carbohydrate content. Additionally, soy is a complete plant protein containing all of the essential amino acids our bodies need.

Foods made from soy include tofu, edamame (fresh soy beans), miso (a traditional Japanese seasoning made of a thick soy-based paste used in sauces, spreads, pickling, and soups), and tempeh (a cooked and slightly fermented soybean patty). Some are made with soybean extracts: soy isolate, soy protein concentrate, soy protein flours, soy milk, soy yogurt, soy-based infant formula and gluten-free breads. Meat alternatives like soy vegetable burgers are good substitutes for meat, poultry, and other animal-based foods because of their high quality protein.

Tip: Excellent sources of soy protein include soy milk, tofu, tempeh, miso, and edamame. Give them a try!

The fat in soybeans are primarily polyunsaturated and monounsaturated fats, which are the heart-healthy fats. Soybeans are one of the few plant foods that provide the omega-6 (linoleic) and omega-3 (alpha-linolenic) acids, both essential fatty acids.

Nutritionally, soy is a good source of fiber, B vitamins, calcium, iron, and other vitamins and minerals. Soy isoflavones are special substances found in soybeans that work in combination with the soy protein, possibly providing additional health benefits. The two main isoflavones in soybeans, genistein and daidzein, have weak estrogen-like effects.

Ways to Add Soy

If you are not familiar with soy products, you may want to start by experimenting with some of the snack foods or combining soy products with regular products, such as making a vegetable dip with half-silken tofu and half-regular sour cream. In recipes with meat, start by replacing some of the meat with tofu or soy crumbles. In lasagna, use half ricotta cheese and half pureed tofu or soy cheese. Just be aware that soy products will have different textures and culinary characteristics than the foods you are used to eating, so start slowly.

Health Benefits

The 2015–2020 Dietary Guidelines for Americans notes that “a healthy eating pattern can include a variety of soy food products.” The research on soy, soy protein, and soy isoflavones supports the safety of soy’s consumption and its positive health impacts.

When it comes to heart health, soy protein is beneficial in lowering LDL cholesterol without an unfavorable effect on HDL cholesterol or triglycerides.

Recent research suggests that consumption of soy may have a more moderate effect in lowering blood cholesterol than previously believed. As a result, the U.S. Food and Drug Administration is proposing a removal of the authorized health claim stating that “consuming 25 grams of soy protein a day may reduce the risk for heart disease.” The proposal still allows for a qualified health claim on the label of products containing soy, which simply means that the evidence is not as strong as necessary to make the previous statement. For those with high blood pressure, consumption of soy protein and soy isoflavones can help lower blood pressure. It is not clear whether this is due to the soy compounds themselves or the fact that these foods replace foods that are high in saturated fat and cholesterol.

Other areas of research indicate that soy isoflavones help with bone mineral density in postmenopausal women. The components in soy (fiber, isoflavones, protein, and oligosaccharides) may help increase the amount of beneficial bacteria that make up the gut microbiome. Diets containing soy may also protect against colorectal, prostate, and endometrial cancers. In regard to breast cancer, new research indicates that consuming soy may actually lower breast cancer risk, whereas at one time it was thought to increase risk. Research is ongoing in all of these areas, and it is always best to discuss your personal health situation with your medical provider.

Shopping Tips

There is a wide array of fresh, canned, dried, and frozen soy-based products at the grocery store.

Dairy aisle

Most dairy products are now available with soy as a base, including milk, cheese, yogurt, and sour cream. Some dairy foods may have added soy protein to boost their protein content, so be sure to read the ingredient list.

Eggs

Soy egg replacers

Freezer case

Edamame, soy bacon, soy burgers, soy crumbles (ground meat substitute), soy entrees, soy-based ice cream

Grocery aisle

Canned black and yellow soybeans, dried soybeans, miso, seasoning mixes with soy, soy cereal, soy flour, soy jerky, soy nut butter, textured soy protein (TSP), soy beverage powders

Meat counter

Garden or soy burgers, soy hot dogs

Produce

Edamame (in pod or shelled), soy sprouts, tempeh, tofu

Snack aisle

Soy protein bars, soy nut trail mix, soy nuts

Recipe: Strawberries, White Bean and Edamame Salad

”A flavorful, enticing mix of fresh strawberries, white beans, and edamame in a light vinaigrette, nested on baby spinach, and topped with crumbled feta cheese.”

Serving size: 4

Ingredients

For the vinaigrette:

  • 1½ tablespoons extra virgin olive oil
  • 2 tablespoons balsamic vinegar
  • ¼ cup apple juice
  • ¼ teaspoon salt
  • teaspoon pepper

For the salad:

  • 1½ cups cleaned, sliced strawberries
  • 1½ cups shelled edamame, cooked
  • 1 15-ounce can low-sodium white beans, rinsed and drained
  • ½ cup chopped red onion
  • 2 tablespoons chopped fresh basil
  • ½ cup crumbled feta cheese
  • 6 cups baby spinach

Directions

Cook edamame according to package directions while preparing remaining ingredients. Once cooked, rinse edamame under cool water and drain. In a small bowl, whisk vinaigrette ingredients. In a medium bowl, toss together strawberries, white beans, and edamame. Serve on individual plates by nesting strawberries, white beans, and edamame mix atop spinach. Drizzle with dressing.

Nutrient Information

Per serving: calories 270, total fat 10 g, saturated fat 2 g, sodium 350 mg, total carbohydrate 30 g, dietary fiber 10 g, protein 14 g.

Source

What’s Cooking? USDA Mixing Bowl.”

Examine Your Choices

FoodSourceWhat I buy nowWhat I plan to buy/change
Example: Stir fryProteinBeef cubesTofu or edamame

My goal: Have one meatless meal each week by substituting with soy.

Sources

Duyff, R. Academy of Nutrition and Dietetics Complete Food and Nutrition Guide. 5th ed. New York: Houghton Mifflin Harcourt, 2017.

Messina, V. “Soyfoods and Heart Disease.” Today’s Dietitian 18, no. 4 (April 2016): 18–22.

U.S. Department of Health and Human Services and U.S. Department of Agriculture. 2015–2020 Dietary Guidelines for Americans. 8th ed. December 2015.

U.S. Food and Drug Administration. “Statement from Susan Mayne, Ph.D., on proposal to revoke health claim that soy protein reduces risk of heart disease.” October 30, 2017.

Webster, A. “Sound Science: History of Soy and Health.” International Food Information Council, December 5, 2017.

Prepared by Sharon McDonald, senior extension educator/food safety specialist. Reviewed by Lynn James, senior extension educator.

Authors

Nutrition research and education Diabetes education Child overweight prevention Food Safety education Food Preservation

More by Lynn James, MS, RDN, LDN 

Food Safety Retail Food Safety for Volunteer Groups Home Food Preservation Home and Consumer Food Safety Nutrition

More by Sharon McDonald, MEd, RD, LDN 

J. Lynne Brown, Ph.D., R.D.