American Society For Nutrition



Excellence in Nutrition Research and Practice
Posted on 09/22/2009 at 12:55:06 PM by Student Blogger
By: Rebecca K.

I recently read: The Whole Soy Story: the dark side of America's favorite health food, by Kaayla T.Daniel, PhD, CCN. The Whole Soy Story is a well-researched and comprehensive exposÉ of soy—conveyed through Daniel's nutritionist point of view.  Below I offer a glimpse into what I learned from this eye-opening and very educational book.

Soy originated in Asia, but it was not a substantial part of the traditional Asian diet. In the United States, John Harvey Kellogg (of Kellogg's cereals) and Henry Ford popularized soy. Soy is a cheap and non-animal protein source that constitutes myriad products. Following the Food and Drug Administration's (FDA) 1999 approval of a soy ‘health claim,' soy and soy products became even more associated with ‘health food.'

Daniel shows throughout her book why soy is the antithesis of a health food. Soybeans have high levels of phytates (‘four times that found in chickpeas')—causing calcium, iron, and zinc malabsoprtion and often deficiency, high levels of oxalates, low levels of methionine and chloride, high levels of manganese, high levels of protease inhibitors, among other components (e.g. lectins). Soy also contains allergens, goitergens, and phytoestrogens (i.e plant estrogens, which can act as strong endocrine disrupters in the human body). While isoflavones are a type of phytoestrogen that exists in many plants, they are at high concentrations in soy. Soy isflavones interfere with the brain; affecting learning, memory, and the birth of new brain cells. Thus, eating tofu, among both middle-aged men and women, is associated with cognitive decline, senile dementia, and brain atrophy later in life.

Infants fed soy-based formula may suffer even greater nutritional consequences. Soy-based formula is fortified with zinc, iron, and calcium, which subsequently interfere with mineral absorption (e.g. copper and zinc); and also contains “the equivalent of three to five birth control pills per day” and 100 times the aluminum found in breast milk. Infants consuming these formulas also ingest 75 to 80 times more manganese than those breast-fed. Both excess manganese and isoflavones consumed during infancy have been attributed to behavioral (e.g. ADD; crime) and endocrine system disorders. Soy consumption during infancy also likely delays (boys) or accelerates (girls) sexual maturation.

Interestingly, however, it was the Federation of American Society for Experimental Biology (FASEB) who spoke out against soy as a nutritional source, stating in 1979 that “the only safe use for soy protein isolates was to strengthen the sealers of cardboard packages.” According to Daniel, “soy protein isolate (SPI) is mixed with nearly every food product sold in today's stores,” and is “the major ingredient in most of today's soy infant formulas.” Despite the FDA's approved health claim, the FDA still does not list soy protein as a ‘generally recognized as safe (GRAS)' food additive. Thus, while the Select Committee of GRAS Substances recommended in 1979 that 150 milligrams of soy protein per day was the “maximum safe dose,” the soy ‘health claim' promotes a consumption of at least 25 grams soy protein per day for heart-health benefits.

So think twice about that next handful of edamame (16.6g protein per 100g), fork full of firm tofu (15.8g protein per 100g raw), or processed soy product; and about feeding soy-based formulas to infants.

But this is by no means the whole soy story—you'll have to read the book for that!

Daniel, K.T. (2005). The whole soy story: the dark side of America's favorite health food. Washington, DC: New Trends Publishing, Inc.