Tea Time: Soy Myths and Facts

Research provided by Emily Winokur, Dietetics Student at University of Central Missouri ('19)​

• Soy can be found in whole soybeans (edamame), tempeh, tofu, soy milk, soy flour, soy protein isolate (can be found in protein powders, protein bars, and some meat substitutes), soybean oil
• 80% of soy currently produced in the US is used as animal feed
• According to the USDA, 94% of soybean farmland in the US was used to grow genetically engineered soybeans in 2014
  • GM soybeans could mean less use of pesticides and herbicides
• Health Benefits/Concerns
  • It contains all 9 essential amino acids, equivalent to an animal protein
  • The soybean is high in protein, and is often a staple food in vegetarian and vegan diets
  • 25 grams of soy protein per day (2 to 4 servings) has been shown to reduce the risk of heart disease
  • Some studies have suggested that a diet including soybeans and soy based products benefits cardiovascular health, weight loss, lower LDL cholesterol and possible prevention of certain cancers
  • Other studies have showed that certain components of soy can be harmful by stimulating the growth of breast cancer cells and negative effect on thyroid health
    • Soy contains an estrogenic compound called isoflavones (or phytoestrogens) that can mimic estrogen in the body and can bind to estrogen receptors (was believed to allow the growth of the cancer cells)
    • A review of soy and breast cancer published in Nutrition Journal stated there is little evidence that soy will increase breast cancer risk in healthy adults
    • The latest science from American Institute for Cancer Research shows soy consumption has a slightly protective or no effect on breast cancer risk
      • Consuming these foods in adolescence may have a protective effect against breast cancer
    • Soy may actually help with menopausal and breast cancer tx symptoms:
      • hot flashes and night sweats
      • joint pain
      • fatigue
      • hair thinning/loss
      • memory problems
    • Regarding interference with thyroid medication for those with hypothyroidism, the medication is often taken on an empty stomach, so absorption isn’t an issue
      • Often the same recommendations are made for other foods or supplements that may interfere with this medication (these include iron supplements, calcium supplements, antacids with aluminum or magnesium, some other medications, walnuts are some examples)
      • May require an increased dose of thyroid hormone in hypothyroid patients, however, they need not avoid soy foods
      • Some soy foods contain goitrogens, substances that interfere with the production and utilization of the thyroid hormone thyroxine
        • These include cassava, millet, and cruciferous vegetables
        • Most of these goitrogens, however, are of no clinical importance
        • However, soy effects (negative) on the thyroid involve a critical relationship with iodine (requires deficiency) among other connections
  • Soy can effect mineral absorption (such as iron) due to its phytate content
    • Whole grain products actually do the same thing
    • The iron in soy is shown to be well-absorbed
• Soy is among the top 8 most common food allergies
  • Others include milk, egg, peanuts, tree nuts, fish, shellfish, and wheat
  • many kids outgrow their soy allergy
• Conclusion
  • Soy is considered a safe, beneficial food when leaning toward the less processed versions (actually helps prevent breast cancer)
    • To maximize the benefits of soy, eat natural and minimally processed sources
      • Tofu, tempeh, soy nuts, soy milk, and edamame are the best options
    • Limit the more processed sources include soy protein isolate and hydrogenated soybean oil
• Recipes from Chef Catherine Brown on Facebook: "A Seat at My Table"
  • Rice Noodle Bowls with Baked Tempeh
  • Smoky Tempeh Apple Bites
  • Autumn Salad with Grilled Figs
  • Tofu Scramble