Soy’s Anti-nutrients

By Cat, Mar 2007

  • See also:1Whole Foods (About) Menu; 2. Soy’s Impact on Health on my old website: 3.  Soy Infant Formula;
  • Includes: 1. Ancient History: Is Soy a Food? 2. Problematic Soy Anti-nutrients; 3. Soy Isoflavones; 4. Soy Protein Isolates (SPI); 5. Debunking Studies from the Soy Industry; 6. Soy Protein Isolate (SPI)  Lacks GRAS (Generally Recognized as Safe) Status; 7. The Next “Asbestos” — Potential Litigation

It is true that soy contains beneficial nutrients as well as the anti-nutrients* described in the following essay.  The food industry is very quick to laud the good, and ignore or downplay the bad, and ignore the differences between fermented and unfermented soy.  But the truth may well be that the bad in unfermented soy outweighs the good, especially when fed to infants who are most vulnerable, developmentally, to the bad side of soy.

*Anti-nutrients are natural toxins in a seed that block the digestion and/or absorption of nutrients in a food, and/or protect the viability of the seed by sickening animals that  eat the seed.

The following essay the first segment condensed “Newest Research On Why You Should Avoid Soy:  Cinderella’s Dark Side” (1), by Sally Fallon & Mary G. Enig, Ph.D. (1). While there is a fair amount of political content in the original article, I only focus on the health content.  Those who are interested in the political content can read the entire article. 

Another article on the problems of Soy can be found in the July/August 2007 issue of Utne Reader:  The Dark Side of Soy (2), by Mary Vance Terrain. 

Ancient history; is soy a food?

While the soybean was designated one of the five sacred grains by the Chinese during the Chou Dynasty (1134-246 BC), pictographs from that era, and agricultural literature of the period, indicate soy was not used as a food, but rather as a method of fixing nitrogen in the soil.  [The other four sacred grains are barley, wheat, millet and rice.]

During that dynasty they discovered how to ferment the soy, making edible products such as tempeh, natto, miso, and soy sauce; or to precipitate soy to make bean curd (tofu). The use of these soy products soon spread to other parts of the Orient, notably Japan and Indonesia. But use of soybean as a grain or whole bean was not even considered, because they knew that unlike other legumes (such as lentils), soybeans contain large quantities of natural toxins or “antinutrients.”

The soybean has only been used as food in American culture since the early 20th century.  The 1913 USDA handbook listed soy, not as a food, but as an industrial product.  In less than a century, soy has changed from a crop with only industrial uses, to one that covers 72 million acres of American farmland, mostly used to feed livestock (chickens, turkeys, pigs, and cows), and farmed salmon, or highly processed to produce oil for margarine, shortenings and salad dressings. Most of the soy consumed in the US is not fermented.

Problematic Soy Anti-nutrients

Trypsin inhibitors (and inhibitors of other protease enzymes) 

These block ability to digest protein. This produces serious gastric distress, reduced protein digestion, and chronic deficiencies in amino acid uptake. Inhibition of trypsin may also cause pathological enlargement of the pancreas, and cancer.  Trypsin inhibitors are deactivated during fermentation, and precipitated out in the process of making curd.

Haemagglutinin inhibitors:

Haemagglutinin is a clot-promoting substance that causes red blood cells to clump together. Haemagglutinin inhibitors and trypsin inhibitors act together as potent growth inhibitors, which are deactivated during fermentation, and precipitated out in the process of making curd.


These anti-nutrients  depress thyroid activity by interfering with thyroid uptake of iodine.  The genistein in soy blocks the activity of the thyroid peroxidase enzyme (which adds iodine atoms to the thyroid hormone molecules).

Phytic acid and phytates

These are present in the bran or hulls of all seeds, but are especially concentrated in soybeans. They block uptake of dietary essential minerals – calcium, magnesium, copper, iron and especially zinc – in the intestinal tract; not only these minerals present in the soybean, but also those from other digesting foods.  The particular phytates in soy are highly resistant to normal phytate-reducing techniques such as sprouting, and long, slow cooking. Only a long period of fermentation will reduce phytate content. Certain food combinations can reduce the effect of phytates; for example, consuming tofu with meat reduces the mineral-blocking effects.

The blocking of zinc uptake is even more profound than that of the other minerals.  Zinc deficiency can cause a “spacey” feeling that some vegetarians may mistake for the “high” of spiritual enlightenment.  Zinc is required for healthy functioning of the brain, nervous system, and reproductive system; is involved in protein synthesis and blood sugar control; is a co-factor for many enzymes; and plays a vital role in the immune system.

While milk consumption is given as the reason why second-generation Japanese in America grow taller than their native ancestors, some investigators postulate that the reduced phytate content of the American diet is the true explanation.  Both Asian and Western children (who do not get enough meat and fish products to counteract the effects of a high phytate diet) frequently suffer rickets, stunting and other growth problems.


Approximately 99% of soy is genetically modified; and has one of the highest percentages of contamination by pesticides of any of our foods.

Soy Isoflavones 

The health industry has been making much of claims that the isoflavones present in soy products provide relief from symptoms of menopause, including hot flashes, mental fogginess, mood swings, and osteoporosis.  These isoflavones are powerful phyto- (plant) estrogens. Genistein, the isoflavone from soy described above as problematic for thyroid activity, is the predominant soy isoflavone used for menopausal symptoms

Phytoestrogens are natural substances produced by plants that act like estrogens in animal systems.  They have a molecular structure similar to estradiol, one of the human estrogens.  Common sources are the isoflavones in soy, lignans in flax seed, and flavonoids in herbs such as black cohosh, red clover, and dong quai.

However, the health claims for isoflavones may be overblown, and furthermore, the isoflavones found in soy are known to be quite toxic. (Refer to Soy Alarm Part 2: Impact on Health – links to the Diet section on my old site)

Soy Protein Isolates (SPI)

SPI, as in soy protein powder and TVP (textured vegetable protein), once considered a waste product, is not something you can make in your own kitchen.  Production in industrial factories involves processes that further degrade the food quality of the bean:

  1. Fiber is removed by soaking in an alkaline solution.
  2. The beans are then washed in an acid bath to neutralize the alkalinity, resulting in the SPI product, which can be used in soy protein powders and animal feed, or further processed to TVP.
  3. TVP is made by high-temperature, high-pressure extrusion processing of the soy protein isolate.

This high temperature processing does remove much of the trypsin inhibitors from the bean product, but it negates the reason for consuming this protein product in the first place:  it totally denatures the protein molecules, rendering them largely ineffective and indigestible, which in turn causes problems for the digestive system.

SPI processing leads to contamination by many poisons:

  • Aluminum, a toxic heavy metal and potent poison leaches into the slurry during soaking and washing in aluminum tubs.
  • Potent carcinogenic nitrites, are formed during spray-drying.
  • Lysinoalanine, a cross-linked amino acid, is a renal toxin formed during alkaline processing.
  • MSG (monosodium glutamate) and other numerous artificial flavorings, are known toxins used to mask the strong “beany” taste, and impart the flavor of meat.

SPI in animal feed – especially in livestock feed

A major use of SPI is in animal feed, but this feed presents many problems for the animals (based on results of animal feeding studies). The following nutrients are reduced or blocked by the SPI, requiring supplementation of essential nutrients:

  • Lysine: Because the protein is rendered mostly indigestible, the animals fed on SPI need lysine supplementation for proper growth, as lysine is an essential amino acid for most animals, including humans.
  • Vitamins E, K, D & B12
  • Minerals: If not supplemented with calcium, magnesium, manganese, molybdenum, copper, iron and zinc, the animal will develop deficiency symptoms due to the action of phytic acid remaining in the SPI.

Animals in the studies develop enlarged organs, particularly the pancreas and thyroid gland, and suffered increased deposition of fatty acids in the liver.

Debunking Studies from the Soy Industry

The soy industry counters the problems listed above with studies of their own in effort to show that soy is a nutritious replacement for traditional foods.  For example, the “Nutritional Quality of Soy Bean Protein Isolates: Studies in Children of Preschool Age“, sponsored by the Ralston Purina Company.

In this study a group of Central American children suffering from malnutrition, showed heath improvements after being fed a 2-week diet that replaced their traditional foods with a soy protein drink and sugar. However, these findings are a masking of the real truth.  What the study did not report to the media:

  • Before being treated with the soy diet, the children were stabilized and brought into better health by feeding them native, traditional foods, including meat and dairy products.
  • During the 2 weeks on the soy diet, the researchers noted that most of the children:

> vomited “occasionally,” usually after finishing a meal;

> suffered from periods of moderate diarrhea (over half the population);

> had upper respiratory infections; or

> suffered from rash and fever.

  • Researchers were obliged to supplement the soy-sugar mixture with nutrients largely absent in soy products, notably: vitamins A, D, & B12; and minerals iron, iodine & zinc.

SPI (Soy Protein Isolate) Lacks GRAS (Generally Recognized as Safe) Status

The Food, Drug and Cosmetic Act requires all food additives not in common use prior to 1958 to undergo study, and be approved as “Generally Recognized as Safe” (GRAS) before they can be used in foods.  While soy protein isolate (SPI) does have GRAS status for use as a binder in cardboard boxes that contain food, it has yet to gain this approval for use as a food additive.  Yet it is present in many foods, including infant formula, because food manufacturers have blatantly flown in the face of the law, even getting a supportive nod from the FDA. How did this happen?

The Nixon administration in 1972 directed a re-examination of substances believed to be GRAS, but ineligible for grandfathered status, in the light of any scientific information then available.  This included two protein isolates introduced after 1958:  casein (from milk), and SPI (from soy).  Casein was codified as GRAS in 1978.  In 1974, a literature review of SPI was begun. While the literature recognized many antinutrients in SPI, including trypsin inhibitors, phytic acid, and genistein, the FDA dismissed discussion of adverse impacts by requiring “adequate processing” to remove the toxic substances.

Genistein could be removed with an alcohol wash, but processors have avoided this procedure because it is too expensive.  Trypsin inhibitor content could be removed only with long periods of heat and pressure, but the FDA has never imposed requirements to do so.

The FDA was more concerned with toxins formed during processing, than those inherent in the soy.  They focused their attention on known carcinogens: nitrites and lysinoalanine.  Even at low levels of consumption — averaging 1/3 of a gram per day at the time — the presence of these carcinogens was considered too great a threat to public health to allow GRAS status.  Safety specifications and monitoring procedures were called for, before granting GRAS status for use in foods. These were never performed, and SPI has never been granted GRAS status.

Instead, SPI must be subject to premarket approval procedures each time manufacturers intend to use it as a food or add it to food.  When infant formula containing SPI was introduced in the 1960s, it was a new product with no history of any use at all.  Because soy protein did not have GRAS status, premarket approval was required.  But it was not, and has never been, granted.  The key ingredient of soy infant formula is not recognized as safe by the FDA.  And yet it is available on market shelves. (refer to Soy Alarm Part 3:  Soy Infant Formula for more on this subject).

The Next “Asbestos”  — Potential Litigation

The soy industry is extremely exposed, and has very, very deep pockets.  The number of potential plaintiffs can be counted in the millions.  Juries will hear something like the following:

“The industry has known for years that soy contains many toxins.  At first they told the public that the toxins were removed by processing. When it became apparent that processing could not get rid of them, they claimed that these substances were beneficial. Your government granted a health claim to a substance that is poisonous, and the industry lied to the public to sell more soy.”


  1. Essay by Sally Fallon and Mary G. Enig, PhD. on Mercola’s site: Page 1: and following pages; Page 2:, and Page 3:;  Please refer to  Page 3 of this article for list of their sources.
  2. The Dark Side of Soy by Mary Vance Terrain in Utne Reader, July/August 2007:

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