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The Truth About Non Fermented vs. Fermented Soy Protein


Fermented soy protein comes from soybeans and undergoes a process of allowing the bean curd, or dried tofu, to fully air-dry and ferment from bacteria and fungal spores in the air. After the fermentation process the soy protein, like tofu, is then soaked in brine. Tofu is made like cheese, where the soybean curds are formed by destabilizing the micelles and resulting in tofu. Fermented tofu is like aged cheese, where it is exposed to microorganisms. The big differences are the flavor, increased bioavailability and decreased perishability with the fermented version.

Soy protein in general is a good choice for a high quality protein source. Soybeans have a high Amino Acid Score, are cholesterol-free and contain minimal fats. Fermented soy products are gaining popularity and have quite a few health benefits.

Health Benefits of Fermented Soy Protein

Fermented soy proteins are associated with disease prevention and overall improved health. Trypsin inhibitors are removed during the fermentation process. These inhibitors hinder the ability of your body to absorb some of the health benefits of soy.

  • Fermented soy has been thought to improve bone health. There is 11% of your DV for calcium, 20% DV of magnesium, 65% DV for manganese and 27% DV of phosphorus in 100 grams of Tempeh. These nutrients are all associated with bone health and a reduction in your risk of osteoporosis.
  • Heart health is also associated with fermented soy products. High levels of heart healthy nutrients like niacin, calcium, magnesium, folate, potassium and copper are found in many fermented soy products and are essential for a healthy heart.
  • Menopausal symptoms may also be reduced by adding fermented soy products to your diet. They are a good way to include soy isoflavones into your diet. They are compounds that have estrogen-like effects and soybeans are the richest sources of isoflavones. They are available as glycosides in soybeans and include genistin, glycitin and daidzin.

Commonly Available Fermented Soy Products

  • Natto
  • Tempeh
  • Miso
  • Fermented Soy Milk
  • Soy Sauces
  • Fermented Bean Curd

Concerns of Non-Fermented Soy Proteins

Due to the phytic and oxalic acid levels found in non-fermented soy products, there is some concern that you may not be able to absorb as much nutrition as you might otherwise with fermented versions. The acids may prevent full absorption in the intestinal tracts of some minerals like zinc, calcium, copper, and iron. Another concern is for the goitrogens also found in fresh soy products, these can slow down the function of the thyroid. This can be a concern for people who are already having challenges with absorption of enough nutrients.

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Emily DeLacey MS, RD is a Registered Dietitian and currently working in Jamaica as a HIV/ AIDS Prevention Specialist. She attended Central Washington University for her Bachelor's Degree in Science and Dietetics and continued on after her internship to Kent State University for her Master's Degree in Science and Nutrition, with a focus on public health and advocacy. She served as a U.S. Peace Corps Volunteer in Malawi 2012-2014 working as a Community Health Advisor in a rural village, immersing in the joys of life without electricity or running water. She has been to 20+ countries and 47 of the 50 states in the US. Traveling, adventuring and experiencing new cultures has made her a passionate advocate for the equality of nutrition and wellness for all people.

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