As a natural product grown from the earth, the soybean and soy products have been heavily marketed as healthy, high protein alternatives. While there are several benefits from fermented soy products like tempeh, natto, and miso, approximately 95% of the soy products found in the US today like tofu, soy meat products and soymilk, are standardly not fermented and contain ingredients known to be hazardous to your health, especially when consumed in large quantities.
The good news? The fermentation of soy products can convert minerals like iron, calcium magnesium, potassium, selenium, copper and zinc into more soluble forms so that the body gets more of the provided nutrients. Soy fermentation can also increase the total amount of vitamin and mineral content in the final product, and some of the yeasts commonly used during the fermentation process add large quantities of thiamin, nicotinic acid and biotin, creating an even healthier overall product.1
However, unfermented soy contains large quantities of phytic acid which inhibit your body from absorbing these minerals from your digestive tract into the blood stream. (The fermenting process reduces the phytic acid and thus the health risks). A large quantity of the soy on the market is also bio-engineered, or genetically modified which activates the body’s own defense mechanisms and can lead to allergies and auto-immune diseases.2
Maybe most concerning is that soy beans contain large amounts of phytoestrogens which mimic natural estrogens in the body and are linked to breast cancer. It is important to note that Asian cultures standardly consume less than one tablespoon of fermented soy a day, compared to many Americans now consuming soy milk, hot dogs, burgers and unknowingly, many products containing soy fillers including protein bars and cereals.3
In 2008, the Israeli Health Ministry released the results of a study by a 13-member committee of nutritionists, oncologists, pediatricians and other specialists concluding that “the estrogen-like plant hormones in soy can cause adverse effects on the human body.” They strongly urged consumers to minimize their consumption of soy foods warning that babies should not receive soy formula, that children should eat soy no more than once per day to a maximum of three times per week, and that adults should exercise caution due to increased risk of breast cancer and adverse effects on fertility.4
In October 2009, Cornell University’s Program of Breast Cancer and Environmental Risk Factors issued a warning that women at risk for breast cancer should limit their soy consumption. Cornell noted that researchers once thought that soy phytoestrogens would block the effects of endogenous estrogens in the body to reduce breast cancer risk, but are now seriously concerned about the mounting evidence that high-soy diets cause greater cell multiplication in the breast. Increased cell multiplication is a widely acknowledged risk factor for the development of breast cancer.4, 5
Following this report, the Journal of the American Dietetic Association stated that the high intake of soy may increase breast cancer risk and that “health professionals should take an active role in communicating and clarifying such information.”4
Jill Coleman has been a registered nurse for over 21 years working at a variety of Southern California hospitals including UCLA’s Heart Transplant Step-down Unit and LAUSC County Hospital’s Trauma Unit. She has studied holistic medicine since the late 1990’s, and promotes the use of medicinal grade, whole food and organic remedies in her practice. For more information on foods and menopause, visit her blog at www.JillColemanRN.com.
References: 1) Alive.com “Fermented Soy Foods” by RoseMarie Pierce, BSc Pharm; 2) www.foodrenegade.com/dangers-of-soy; 3) http://www.drpepi.com/soy-protein.php; 4) Wise Traditions in Food, Farming and the Healing Arts, the quarterly magazine of the Weston A. Price Foundation, Fall 2005; 5) http://ecommons.library.cornell.edu/handle/1813/14416