Soy Products Do Not Make You Healthy (part II)
Marketing the Soybean
The truth is, however, that most of us are unlikely to adopt traditional soy products as their principal food. Tofu, bean curd and tempeh (tempe) have a disagreeable texture and are too bland for the Western palate; pungent and musty miso and natto lose out in taste tests; only soy sauce enjoys widespread popularity as a condiment. The soy industry has therefore looked for other ways to market the superabundance of soybeans now grown in the United States and around the world.
Large scale cultivation of the soybean in the United States began only after the Second World War, and quickly rose to 140 billion pounds per year. Most of the crop is made into animal feed and soy oil for hydrogenated fats- margarine and shortening. During the past 20 years, the industry has concentrated on finding markets for the byproducts of soy oil manufacture, including soy “lecithin“, made from the oil sludge, and soy protein products, made from defatted soy flakes, a challenge that has involved overcoming consumer resistance to soy products, generally considered tasteless “poverty foods”. “The quickest way to gain product acceptability in the less affluent society,” said a soy industry spokesman, ” … is to have the product consumed on its own merit in a more affluent society.”11 Hence the proliferation of soy products resembling traditional American foods-soy milk for cows milk, soy baby formula, soy yogurt, soy ice cream, soy cheese, soy flour for baking and textured soy protein as meat substitutes, usually promoted as high protein, low-fat, no cholesterol “healthfoods” to the upscale consumer increasingly concerned about his health. The growth of vegetarianism among the more affluent classes has greatly accelerated the acceptability and use of these ersatz products. Unfortunately they pose numerous dangers.
Processing Denatures and Dangers Remain
The production of soy milk is relatively simple. In order to remove as much of the trypsin inhibitor content as possible, the beans are first soaked in an alkaline solution. The pureed solution is then heated to about 115 degrees C in a pressure cooker. This method destroys most (but not all) of the anti-nutrients but has the unhappy side effect of so denaturing the proteins that they become very difficult to digest and much reduced in effectiveness.12 The phytate content remains in soy milk to block the uptake of essential minerals. In addition, the alkaline soaking solution produces a carcinogen, lysinealine, and reduces the cystine content, which is already low in the soybean.13 Lacking cystine, the entire protein complex of the soybean becomes useless unless the diet is fortified with cystine-rich meat, eggs, or dairy products, an unlikely occurrence as the typical soy milk consumer drinks the awful stuff because he wants to avoid meat, eggs and dairy products.
Most soy products that imitate traditional American food items, including baby formulas and some brands of soy milk, are made with soy protein isolate, that is the soy protein isolated from the carbohydrate and fatty acid components that naturally occur in the bean. Soy beans are first ground and subjected to high-temperature and solvent extraction processes to remove the oils. The resultant defatted meal is then mixed with an alkaline solution and sugars in a separation process to remove fiber. Then it is precipitated and separated using an acid wash. Finally the resultant curds are neutralized in an alkaline solution and spray dried at high temperatures to produce high protein powder. This is a highly refined product in which both vitamin and protein quality are compromised-but some trypsin inhibitors remain, even after such extreme refining! Trypsin inhibitor content of soy protein isolate can vary as much as 5-fold.14 In rats, even low level trypsin inhibitor soy protein isolate feeding results in reduced weight gain compared to controls.15 Soy product producers are not required to state trypsin inhibitor content on labels, nor even to meet minimum standards, and the public, trained to avoid dietary cholesterol, a substance vital for normal growth and metabolism, has never heard of the potent anti-nutrients found in cholesterol-free soy products.
Soy Formula Is Not the Answer
Soy protein isolate is the main ingredient of soy-based infant formulas. Along with trypsin inhibitors, these formulas have a high phytate content. Use of soy formula has caused zinc deficiency in infants.16 Aluminum content of soy formula is 10 times greater than milk based formula, and 100 times greater than unprocessed milk.17 Aluminum has a toxic effect on the kidneys of infants, and has been implicated as causing Alzheimer’s in adults. Soy milk formulas are often given to babies with milk allergy; but allergies to soy are almost as common as those to milk.18 Use of soy formula to treat infant diarrhea has had mixed results, some studies showing improvement with soy formula while others show none at all.19 Soy formulas lack cholesterol which is absolutely essential for the development of the brain and nervous system; they also lack lactose and galactose, which play an equally important role in the development of the nervous system. A number of other substances, which are unnecessary and of questionable safety, are added to soy formulas including carrageenan, guar gum, sodium hydroxide (caustic soda), potassium citrate monohydrate, tricalcium phosphate, dibasic magnesium phosphate trihydrate, BHA and BHT. Nitrosamines, which are potent carcinogens, are often found in soy protein foods, and are greatly increased during the high temperature drying process.20 Not surprisingly, animal feeding studies show a lower weight gain for rats on soy formula than those on whole milk, high-lactose formula.21 Similar results have been observed in children on macrobiotic diets which include the use of soy milk and large amounts of whole grains. Children brought up on high-phytate diets tend to be thin and scrawny.22
Fabricated Soy Foods
A final indignity to the original soy bean is high-temperature, high-pressure extrusion processing of soy protein isolate to produce textured vegetable protein. Numerous artificial flavorings, particularly MSG, are added to TVP products to mask their strong “beany” taste, and impart the flavor of meat. 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 give-away programs. These soy products greatly inhibit zinc and iron absorption; in test animals they cause enlarged organs, particularly the pancreas and thyroid gland, and increased deposition of fatty acids in the liver.23 Human feeding tests to determine the cholesterol lowering properties of soy protein isolate have not shown them to be effective.24 Nevertheless, they are often promoted as having beneficial effects on cholesterol levels.
Cancer Preventing or Cancer Causing?
The food industry also touts soy products for their cancer preventing properties. Isoflavone aglycones are anticarcinogenic substances found in traditionally fermented soybean products. However, in non-fermented soy products such as tofu and soy milk, these isoflavones are present in an altered form, as beta-glycoside conjugates, which have no anti-carcinogenic effect.25 Some researchers believe the rapid increase in liver and pancreatic cancer in Africa is due to the introduction of soy products there.26
The fatty acid profile of the soybean includes large amounts of beneficial omega-3 fatty acids compared to other pulses (legumes); but these omega-3 fatty acids are particularly susceptible to rancidity when subjected to high pressures and temperatures. This is exactly what is required to remove oil from the bean, as soybean oil is particularly difficult to extract. Hexane or other solvents are always used to extract oil from soybeans, and traces remain in the commercial product.
References:
- 11. Coleman, Richard J., “Vegetable Protein-A Delayed Birth?”, J-Am-Oil-Chem-Soc, v. 52, Apr 1975, p. 238A.
- 12. Wallace, G.M., “Studies on the Processing and Properties of Soymilk”, J-Sci-Fd-Agric, v.22, Oct 1971, pp.526-535.
- 13. Berk, Zeki, “Technology of production of edible flours and protein products from soybeans”, FAO Agricultural Services Bulletin 97, Food and Agriculture Organization of the United Nations 1992, p. 85.
- 14. Rackis, J.J., et. al., “The USDA trypsin inhibitor study. I. Background, objectives and procedural details”, Qual-Plant-Foods-Hum-Nutr, v. 35 1985, p. 232.
- 15. Ibid.
- 16. Lonnerdal, B. et. al., “The effect of individual components of soy formula and cows’ milk formula on zinc bioavailability”, Am-Jour-Clin-Nutr, v. 40 Nov 1984, pp. 1064-1070.
- 17. Palmer, Gabrielle, “The Politics of Breastfeeding”, Pandora Press, London, 1993, p. 310.
- 18. Ganse, R. “Doctors still sleuthing cause of food allergies”, Sch-Foodserv J, v. 40 (4), May 1986, pp. 38-39.
- 19. Alarcon, P. et. al., “Clinical trial of home available, mixed diets versus a lactose-free soy-protein formula for the dietary management of acute childhood diarrhea”, J-Pediatr-Gastroenterol Nutr, v.12 (2), Feb 1991, pp.224-232
- 20. “Rackis”, Op. Cit., P. 225.
- 21. Dukakis, E.S., et. al., “Evaluating the nutritional quality of infant formula” Nutr-Res, v. 9 (1), Jan 1989, pp. 93-104.
- 22. “Lonnerdal”, Op. Cit.
- 23. Smith, Allan K. Ph.D. ed., Soybeans: Chemistry and Technology, Vol 1, Avi Publishing Company, Inc. Westport, CT, 1972, p. 183; Jenkins, M. Y., et. al., “Nutritional assessment of twelve protein foods/ingredients”, NutrRes, v. 9 (1), Jan 1989, pp. 83-92.
- 24. Wolfe, B.M., “Elevation of VLDL-cholesterol during substitution of soy protein for animal protein in diets of hypercholesterolemic Canadians”, Nutr-Rep-lnt, v. 32 (5), Nov 1985, pp.1057-1065.
- 25. Coward, L., et. al., “Genistein, daidzein and their beta-glycoside conjugates: Antitumor isoflavones in soybean food from American and Asian diets”, J-Agric-Food-Chem, v. 41 (11), Nov 1993, pp. 1961-1967.
- 26. Katz, Op. Cit.
