Reassessing soy

The purpose of this research paper is to present an in depth discussion regarding modern soy consumption. Allow me to state my opinions up front, and then you can judge my presentation of facts as you may. I am not anti-soy. Moderate quantities of certain soy products can be healthful for most of us, while other soy products should be completely avoided. As with most other cases of food health, the answer of health results from questions regarding production quality and processing methods.


Contrary to many assumptions about the consumption of soy in Asia, soy is not and has never been a staple, or even a major part of any traditional diet. In her book ”What to Eat”, esteemed nutrition professor Marion Nestle wrote that soy has been consumed in China and other Asian countries for millenia; this seems obvious, but, in fact, the story portrayed by her and other mainstream nutritionists is not entirely true1.” ”In China, soy was used by the poor during times of shortage, and even then only after it had been fermented in a lengthy process to destroy the toxic elements of soy2. Products like tofu and soy milk may have existed for millennia, but they were certainly not consumed regularly or in great quantity.

Soy is traditionally used as a compliment to a meal. For example, tofu is commonly used in Japan in miso soup or fish stew; small bowls of these can be healthful parts of a larger meal3. While living in South Korea, I saw that small portions of tofu was often used in stews and side dishes, but rarely in large quantities. Despite the fact that processed soy products are now common in Asia, it has never been traditional to sit down and eat eight ounces of tofu along with a glass of soy milk2.

In America, soy was sometimes fed to animals, never to humans, until a boll weevil infestation destroyed the cottonseed crop around 1915 and soy was used as a substitute for cooking oil production1. This fateful beginning led to the food industry’s realization that soy could be an immensely profitable food, and its unique and at first glance exceedingly beneficial nutritional profile allowed for a number of health claims. As the vegetarian movement gained momentum, soy was valued as an environmentally friendly super food containing all the essential amino acids (proteins)4.

”Health Benefits”

Going into this research report, I deeply wanted to believe that soy could be as healthful as some say it is. On paper, there are numerous beneficial aspects to soy’s nutritional profile, as well as its efficiency of production compared to meat, that would make it a great food.

Proponents of soy offer a laundry list of potential protections from diseases including “heart disease, cancers (stomach, colon, breast, and prostate), menopausal hot flashes, bone loss, cataracts, immune function disorders, muscle damage, kidney disorders, memory loss, weight gain, and . . . anxiety”1.

Soy is considered a complete protein, meaning that it has all eight of the essential amino acids (essential amino acids are proteins that our bodies cannot produce and thus must be consumed in food). This makes it a potentially beneficial source of protein for vegetarians. However, it has low amounts of certain amino acids—methionine, cystein, and tryptophan—making it a somewhat problematic source of protein unless combined with foods containing sufficient quantities of these amino acids2,3.

Unfortunately, some of the health claims regarding soy are of dubious quality. In 1998 a DuPont subsidiary petitioned the FDA successfully for the allowance of health claims linking soy protein to cardiovascular disease prevention1. This petition was based on DuPont’s own research, wherein substituting an ounce or two of soy protein for animal protein daily led to reductions as high as ten percent1. Independent research did not come to the same conclusion, but this has had no effect on FDA labeling practices1. Similar examples of poor research from the soy industry are widespread1.

There are other aspects to the health benefits of soy, which I will touch on throughout this report.

”Phytoestrogens and Goitrogens”

Some consider the type of phytoestrogens in soy to be beneficial. Phytoestrogens are plant compounds with structural similarities to estrogen compounds allowing them to have estrogenic or antiestrogenic effects6.

The phytochemicals in soy, called isoflavones, are weak, plant-based estrogens that can occupy estrogen receptors1,7. This has a number of consequences—some beneficial, some not.

Respected nutritionist Andrew Weil writes that this estrogen receptor occupation can protect the receptors from stronger phytoestrogens, including environmental pollutants, so he recommends soy products as part of a breast cancer prevention program7 . Marion Nestle writes that the isoflavones “work with soy proteins to reduce blood cholesterol levels,” but because they act as estrogens they may “increase the risk of breast and other cancers in women”1.

Furthermore, isoflavones might replicate estrogen in situations where it is not desirable, such as in infants or young children1. Acclaimed natural health specialist Dr. Joseph Mercola also noted that isoflavones are especially prone to causing complications in infants and young children8. One study found that “phytoestrogens may cause boys to exhibit female traits”5.

One measurable isoflavone found in soy is genistein. Problematically, the recommendations of major soy producers lead to extremely high levels of genistein—and presumably other isoflavones—in the blood2. Whereas Japanese males generally consume less than ten milligrams of genistein per day, Protein Technologies International’s recommendation of one hundred grams of soy protein consumed daily adds up to twenty times the genistein content—fully two hundred milligrams2.

Another aspect of isoflavones is that they are goitrogens, or substances that depress thyroid function3. Impaired thyroid function is endemic in Western society, and soy is one of many culprits8. It should be noted that adequate iodine consumption is vital for proper thyroid function, and goitrogen consumers may benefit from a healthful source of iodine like unrefined salts (Celtic sea salt, Himalayan salt, etc.) and sea vegetables.

To come back to the original supportive claim regarding isoflavones—that they are able to block more harmful phytoestrogens from estrogen receptors—it firstly seems obvious that avoiding harmful toxins and taking detoxification steps is more useful to prevent the uptake of harmful receptors. But secondly, in light of other research involving isoflavone consumption linked to cancer, thyroid inhibition, and interference with childhood development, as well as the awareness of the fact that soy producers are recommending unnatural amounts of soy, I am reluctant to accept the health benefits of isoflavones. They seem problematic for most people.

My belief is corroborated by research by two senior US government scientists revealing that “chemicals in soy could increase the risk of breast cancer in women, brain damage in both men and women, and abnormalities in infants”9. This study, involving 3,734 Japanese-American men, found that those who ate the most tofu had “2.4 times the risk of later developing Alzheimer’s disease9.

I feel like I should also address the claim that isoflavones can reduce menopausal symptoms including heart disease and hot flashes, which Marion Nestle wrote about1. In fact, recent research shows that reducing menopausal symptoms may not in fact be desirable8. Even if it was, concentrated soy isoflavone extracts were shown in a recent study to have no effect on menopausal symptoms10.

Fermented forms of soy have lower levels of phytoestrogens, though they are not completely removed3,5. I will discuss these in detail later on.

”Hexane, our health, and the environment”

Hexane is “an explosive neurotoxic substance that is the byproduct of gasoline refinement”11. Why is this relevant? Well, during most soy processing, the soy basically takes a bath in hexane11.

A recent study from the Cornucopia Institute in partnership with found hexane residues in soy oil, soy meal, soy grits, soy-based infant formulas, and other products12. The problem is that there has never been any real research on the effects of hexane on the body11. The FDA doesn’t even require hexane testing11.

This recent discovery is horrifying. If consumer consume to purchase soy products, non-organic products should be avoided at all costs. Remember that if products labels say “made with organic” instead of 100% organic, up to 30% of the ingredients may not be organic11.

Environmental impacts are outside of the purview of this paper. Suffice it to say that soy producers in the US release 21 million pounds of this pollutant annually, or two thirds of all US hexane emissions, and in one instance a waste water treatment system downstream from a soy manufacturing plant exploded because of hexane pollution11,12. The concentration of soy production in a smaller and smaller number of corporations is concerning4. Corporations like Cargill and Archer Daniels Midland successfully lobby the US government for huge agricultural subsidies for soy production, and at the same time are expediting the export of soy production to South America1. As many of you know, soy production in South America is a primary cause of rain forest deforestation13.

”Phytic acid, enzymes, fermentation, and other problems with soy”

Soy contains phytic acid and enzyme inhibitors that can be deactivated not by cooking but only by fermentation3,14 .

Phytic acid is a type of fiber that humans are unable to digest8. It impairs the body’s ability to absorb minerals and can cause serious gastric distress3,8.

Trypsin is an important enzyme for protein digestion and soy contains “trypsin inhibitors,” which prevent proper protein digestion11. Regular soy consumers often have serious protein assimilation problems3.

A number of sources point to mineral absorption issues resulting from soy. Phytic acid results in reduced bioavailability of minerals like zinc and iron, potentially leading to mineral deficiencies3,15. Consumption of isolated soy protein powder was found to cause a negative calcium balance, potentially leading to osteoporosis3. Soy was also found to increase the body’s need for vitamin B123,15. Trypin inhibitors that impact protein digestion strain the pancreas, leading to pancreatic swelling3,15.

Traditionally fermented soy, including miso, natto, tempe, and tamari (soy sauce) offer a number of health benefits11. Traditionally soy sauce—like tamari—is carefully brewed in a complex process requiring up to eight months, whereas the modern bioreactor method of soy sauce brewing yields unnatural amounts of glutamic acid—the same kind found in MSG3. These soy products are good sources of enzymes and beneficial bacteria, aiding good digestion3. Miso is a significant source of vitamin K and other important nutrients3. Traditional ethnic diets always contain fermented foods, such as kimchi in Korea and sauerkraut in Germany, and this “food group” is missing from the Western diet3.

Tofu, soy milk, soy protein powders, and most modern processed soy products are not fermented, and thus contain unsafe levels of phytates and enzyme inhibitors14 .

A couple other things to keep in mind regard soy processing is that the high omega 3 content in soy means that it often goes rancid when processed into flour; soy flour should be completely avoided3. Carcinogens are often formed during soy milk processing as well3. Processed soy is generally high in heavy metals like aluminum, fluoride, and manganese, as well as MSG3.

Finally, soy is heavily genetically modified. 91% of the soy grown in the US is genetically modified5. There is hardly room for a discussion on genetically modified products in this essay. The American Academy for Environmental Medicine recently issued a warning to the public to avoid genetically modified foods16. Recent studies show that GMO soy and other GMO products caused death in rats, DNA changes in rats, reproductive abnormalities in rats, infertility in buffaloes, allergies and immune reactions in humans, death in sheep, death in cows, death in horses, death in water buffaloes, death in chickens, and bleeding stomachs in rats16. To avoid the consumption of genetically modified foods, non-organic soy should be completely avoided.

”Soy-based infant formulas”

Of course, infants have more fragile digestive and immune systems than adults. One would think that concerns regarding phytoestrogens, phytic acid, trypsin inhibitors, genetic modification, and goitrogens would be enough to persuade the public to avoid soy-based formulas. However, this has clearly not been the case.

I hate to keep picking on Marion Nestle as if she was the source of all mainstream nutrition ideas, but she writes in her book that “soy formulas are valuable for infants allergic to milk”1. First of all, if breast milk must be avoided, cow’s milk is a safe and healthful option for infant formulas, and unpasteurized milk is often tolerate by those who do not do well with pasteurized milk3. If cow’s milk is not tolerated, sheep or goats milk often is3. If none of these options are tolerated, resources and recipes for other formula options, including nondairy options, can be found in Sally Fallon’s ”Nourishing Traditions ”and at Dr. Joseph Mercola’s website, (search for “alternative infant formula”).

Let’s not assume that soy is the only last option.

With that in mind, I think that it is important to be aware of the ramifications of using soy formula in infants. Soy is devoid of cholesterol, which is vital for brain and nervous system development. The high levels of toxins in soy products, including hexane, manganese, and aluminum, are particularly damaging to infants8,12.

Phytoestrogens in soy adversely impact hormonal development. Studies show up to 20,000 times the normal amount of estrogen circulating in the bloodstream of male and female infants fed soy formulas8.

No long term research has vindicated the safety of soy formula3. These are dangerous products that should not be in the market.


The best way to eat soy is in fermented forms, such as miso, tempe, tamari, and natto, though these foods do contain some isoflavones. Consuming small amounts of tofu or other non-fermented forms of soy not as a substitute for protein but as part of a soup or side dish, like in traditional Japanese cuisine, should be fine for most people. Non-organic soy products—the overwhelming majority of soy products—should be completely avoided. Health claims of the soy food industry should be regarded with suspicion.

1 Nestle, Marion. (2007). What to Eat. New York: North Point Press.

2 The History of Soy. Retrieved August 22, 2009 from []

3 Fallon, Sally. (2001). Nourishing Traditions. Washington, DC: NewTrends Publishing, Inc.

4 Lappe, Frances Moore. (1991). Diet for a Small Planet. New York: Ballantine Books.

5 Patrick, Kirk. (2009). Japanese Vegetarian Cuisine Explained. Retrieved August 22, 2009 from [].

6 Phytoestrogens. (2009). Retrieved August 22, 2009 from [].

7 Weil, Andrew. (1998). Ask Dr. Weil. New York: Great Bear Publications, LLC.

8 Mercola, Joseph. (2009). Why Soy Can Damage Your Health. Retrieved August 22, 2009 from [].

9 MacArthur, John D. (2000). Soy and Brain Damage. Retrieved August 22, 2009 from []

10 Soy Symptoms Fail to Help Menopause Symptoms. Retrieved August 22, 2009 from [].

11 Croxton, S. (2009). Soy: Dirty Little Secrets. Retrieved August 22, 2009 from []

12 Adams, Mike. (2009). Soy Protein Used in “Natural” Foods Bathed in Toxic Solvent Hexane. Retrieved August 22, 2009 from []

13 (2008). Amazon deforestation due to oil, soy prices. Retrieved August 22, 2009 from [].

14 Wolcott, W, Fahey, T. (2002). The Metabolic Typing Diet. New York: Broadway Books.

15 Myths & Truths about Soy Foods. Retrieved August 22, 2009 from [].

16 Huff, Ethan. (2009). Genetically Modified Organisms Unfit for Human Consumption. Retrieved August 22, 2009 from [].


One response to “Reassessing soy

  1. Answer your damn phone

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