Soy processors have worked hard to get the many antinutrients out of the finished soy product, particularly soy protein isolate (SPI), the key ingredient in most soy foods that imitate meat and dairy products, including baby formulas and some brands of soymilk.
SPI is not something you can make in your own kitchen. Production takes place in industrial factories where a slurry of soy beans is first mixed with an alkaline solution to remove fiber, then precipitated and separated using an acid wash and, finally, neutralized in an alkaline solution.
Acid washing in aluminum tanks leaches high levels of aluminum into the final product. The resultant curds are spray- dried at high temperatures to produce a high-protein powder. A final indignity to the original soybean is high-temperature, high-pressure extrusion processing of soy protein isolate to produce textured vegetable protein (TVP).
Much of the trypsin inhibitor content can be removed through high-temperature processing, but not all. Trypsin inhibitor content of soy protein isolate can vary as much as fivefold. (In rats, even low-level trypsin inhibitor SPI feeding results in reduced weight gain compared to controls.)
However, high-temperature processing has the unfortunate side effect of so denaturing the other proteins in soy that they are rendered largely ineffective. That’s why animals on soy feed need lysine supplements for normal growth. Nitrites, which are potent carcinogens, are formed during spray drying, and a toxin called lysinoalanine is formed during alkaline processing. Numerous artificial flavorings, particularly MSG, are added to soy protein isolate and textured vegetable protein products to mask their strong “beany” taste and to impart the flavor of meat.
In feeding experiments, the use of SPI increased requirements for vitamins E, K, D and B12 and created deficiency symptoms of calcium, magnesium, manganese, molybdenum, copper, iron and zinc. Phytic acid remaining in these soy products greatly inhibits zinc and iron absorption; test animals fed SPI develop enlarged organs, particularly the pancreas and thyroid gland, and increased deposition of fatty acids in the liver.
Yet soy protein isolate and textured vegetable protein are used extensively in school lunch programs, commercial baked goods, diet beverages and fast food products. They are heavily promoted in third world countries and form the basis of many food giveaway programs.
In spite of poor results in animal feeding trials, the soy industry has sponsored a number of studies designed to show that soy protein products can be used in human diets as a replacement for traditional foods.
An example is “Nutritional Quality of Soy Bean Protein Isolates: Studies in Children of Preschool Age”, sponsored by the Ralston Purina Company. A group of Central American children suffering from malnutrition was first stabilized and brought into better health by feeding them native foods, including meat and dairy products. Then, for a two-week period, these traditional foods were replaced by a drink made of soy protein isolate and sugar.
All nitrogen taken in and all nitrogen excreted was measured: the children were weighed naked every morning, and all excrement and vomit gathered up for analysis. The researchers found that the children retained nitrogen and that their growth was “adequate”, so the experiment was declared a success.
Whether the children were actually healthy on such a diet, or could remain so over a long period, is another matter. The researchers noted that the children vomited “occasionally”, usually after finishing a meal; that over half suffered from periods of moderate diarrhea; that some had upper respiratory infections; and that others suffered from rash and fever. That is not what real food is supposed to do to a child.
It should be noted that the researchers did not dare to use soy products to help the children recover from malnutrition, and were obliged to supplement the soy-sugar mixture with nutrients largely absent in soy products – notably, vitamins A, D and B12, iron, iodine and zinc.
MARKETING THE PERFECT FOOD
“Just imagine you could grow the perfect food. This food not only would provide affordable nutrition, but also would be delicious and easy to prepare in a variety of ways. It would be a healthful food, with no saturated fat. In fact, you would be growing a virtual fountain of youth on your back forty.”
The author is Dean Houghton, writing for The Furrow, a magazine published in 12 languages by John Deere. “This ideal food would help prevent, and perhaps reverse, some of the world’s most dreaded diseases. You could grow this miracle crop in a variety of soils and climates. Its cultivation would build up, not deplete, the land…this miracle food already exists… It’s called soy.”
Just imagine. Farmers have been imagining – and planting more soy. What was once a minor crop, listed in the 1913 US Department of Agriculture (USDA) handbook not as a food but as an industrial product, now covers 72 million acres of American farmland. Much of this harvest will be used to feed chickens, turkeys, pigs, cows and salmon. Another large fraction will be squeezed to produce oil for margarine, shortenings and salad dressings.
Advances in technology make it possible to produce isolated soy protein from what was once considered a waste product – the defatted, high-protein soy chips – and then transform something that looks and smells terrible into products that can be consumed by human beings. Flavorings, preservatives, sweeteners, emulsifiers and synthetic nutrients have turned soy protein isolate, the food processors’ ugly duckling, into a New Age Cinderella.
The new fairy-tale food has been marketed not so much for her beauty but for her virtues. Early on, products based on soy protein isolate were sold as extenders and meat substitutes – a strategy that failed to produce the requisite consumer demand. The industry changed its approach.
“The quickest way to gain product acceptability in the less affluent society,” said an industry spokesperson, “is to have the product consumed on its own merit in a more affluent society.” So soyis now sold to the upscale consumer, not as a cheap, poverty food but as a miracle substance that will prevent heart disease and cancer, whisk away hot flushes, build strong bones and keep us forever young.
The competition – meat, milk, cheese, butter and eggs – has been duly demonized by the appropriate government bodies. Soy serves as meat and milk for a new generation of virtuous vegetarians.