top of page

Soy Protein Isolate and the Its Effects on Health

What is soy?

“Diets low in saturated fat and cholesterol that include 25 grams of soy protein a day may reduce the risk of heart disease,” stated a health claim approved by the FDA in 1999 regarding soy foods. This claim paved the way for an explosion in the soy-based food industry. Soy is known as a “healthy alternative” to meat, a “non-allergenic” to milk and a “low cost” protein that will feed millions.

In ancient times, the Chinese considered the soybean to be a national treasure, and even referred to it as “the yellow jewel.” Soy originated as a solution to nitrogen-deficient soil and was only introduced as a fermented food no earlier than 2500 years ago. In Asian countries, it was not until the soybean was processed and the trypsin inhibitor was deactivated, that they considered the soybean suitable for food. Before that, they considered it inedible. Today in North America we have endless options of processed soy: soy milk, soy protein powder, soybean oil, etc.

Toxic boxes

More than two thirds of the U.S. soybean crop comes from genetically modified soybeans patented and sold by Monsanto. They developed this genetically-modified bean to be resistant to the weed killer Roundup so that farmers could kill the weeds without damaging the soy crop. Soy protein isolate is added to foods because of its emulsifying and texturizing properties. Consumers would never guess that soy protein isolate was not developed nor intended for consumption. The Federation of American Societies for Experimental Biology (FASEB) concluded in 1970 that it was only safe for use as a binder and sealer for cardboard boxes. Investigators were concerned that the carcinogen nitrosamine and the toxin lysinoalaine found in the soy protein isolate used in the binding would contaminate the food contents inside, but they concluded that the amount would be too low to pose a health hazard. However, the same investigators expressed concern about infants being exposed to soy protein isolate, which the industry was beginning to use in soy infant formulas.

Here, there, everywhere

Soy protein isolate is mixed with an abundant amount of food products sold in stores. Seriously, it’s everywhere. You can find it in energy bars, muscle-man powders, breakfast shakes, burgers, hotdogs, baby foods, baked goods, bakery mixes, beer and ale, beverage powders, cereals, cheese, diet food products, frozen desserts, infant formula, imitation meats, non-dairy products, pasta, processed dairy, soups, supplements, and vegetarian foods. It is also used in school cafeterias, hospitals, and prisons as a filler to help cut the cost of items such as hamburgers.

Washed, dipped, and sprayed

Soy protein isolate is a highly refined product meant to improve the flavor, remove the bean taste, and improve the digestibility of the traditional soy bean. This process sacrifices the vitamin, mineral and protein qualities in the soy bean. It is also more deficient in sulfur-containing amino acids than any other soy protein product.

The levels of toxins and carcinogens are greatly increased during the refining process of soy protein isolate. The process begins with defatted soybean meal that is mixed with a caustic alkaline solution to remove the fiber. Once the fiber has been removed, it is washed in an acid solution to precipitate out the protein. Next, the protein curds are dipped into another alkaline solution and spray dried at extremely high temperatures. Besides the aluminum present in the soy protein isolate, monosodium glutamate (MSG), a neurotoxin, is formed during processing. The high aluminum content is often associated with iron deficiency, decreased bone mineral content and Alzheimer’s disease, to name a few.

The soy protein isolate can also be spun into protein fibers. In this process the fat, flavor, color and fiber-binding agents are incorporated into the fibers to imitate the texture found in animal muscle meats. This process makes the soy protein isolate difficult to digest and is extremely hard on the GI tract, resulting in discomfort and a significant amount of flatulence.

The soy protein isolate that provides that familiar ground meat-like texture (found in soy chili and hundreds of other products), contains 38 petroleum compounds including but not limited to: butyl, methyl, ethyl esters of fatty acids, phenols, diphenyls and phenyl esters; abietic acid derivatives, diehydroabietinal, hexanal and 2-butyl-2octenal aldehydes, dehydroabietic acid methyl ester; dehydroabietene and abietatriene. Human bodies are not designed to consume these petroleum products and they could cause symptoms of skin irritation, eye irritation, dizziness, headache, nausea and, in extreme cases, death.

Don’t be deceived

Soy protein isolate, which appears in an endless amount of food items, has many detrimental effects on our health. All soybeans, not just the soy protein isolate, contain goitrogens, allergens, protease inhibitors and other antinutrients and toxins that damage the digestive, immune, and neuroendocrine systems. Consumption of these toxins put consumers at increased risk for a wide variety of health problems, including cancer. We have been led to believe that soy foods, including the soy protein isolate, are the natural heritage of Asia and that it was and continues to be eaten in great quantities. In fact, the Chinese, Indonesian, Korean, Japanese and Taiwanese people only consume an average 8.6 grams of protein per day. This is 65% less than the U.S. government’s recommended dose of 25g for protection against cardiovascular disease. Furthermore, Asian countries consume substantially less old-fashioned soy products, opting for whole food soy products such as miso and tempeh instead. Americans on the other hand, tend to prefer imitation products such as soy protein isolate, soy milk, veggie burgers and TVP chili. Are we going to continue down this dark path soy has paved for us, knowing it has created an epidemic of disease in humans or are we going to start a movement where we demand honesty, integrity and eat whole food? The choice is ours, the time is now.


Daniel, Kaayla. The whole Soy Story. Washington, New Trends Publishing Inc. 2005.

Brownstein, David & Shenefelt, Sheryl. The Soy Deception. Birmingham, Health Living. 2011.

Gregg, Dianne. The Hidden Dangers of Soy. Denver, Outskirts Press Inc. 2008.


bottom of page