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WHAT ABOUT SOY?
The litany of dangers with soy products, according to the article by Fallon and Enig, is nearly endless. Given the rapidly expanding role that soy in its many forms has come to play in the Western diet, these accusations are extremely serious. ARE SOYFOODS A BLESSING OR A CURSE?
As the evidence of soy's health benefits kept accumulating, sales and consumption skyrocketed. But, according to the article by Sally Fallon and Mary Enig, this is all a tragic mistake, because soy is far indeed from living up to the many health claims that its proponents have made for it. Quite to the contrary, Fallon and Enig say, "the soybean contains large quantities of natural toxins or 'antinutrients,' (including) potent enzyme inhibitors that block the action of trypsin and other enzymes needed for protein digestion... They can produce serious distress, reduced protein digestion and chronic deficiencies in amino acid uptake." These are serious allegations, because soy is often consumed precisely for its considerable protein levels. In my view, there is a kernel of truth behind these charges, though one that Fallon and Enig greatly overstate. It is true that the protein in cooked soybeans is slightly less digestible than that found in most animal foods. However, when soybeans are made into soymilk, tofu, tempeh, and the other common forms of soyfoods, their protein digestibility is enhanced and becomes similar to animal foods. Any negative impact on protein digestibility due to the presence of the enzyme inhibitors found in soybeans is rendered nearly irrelevant in such foods. And even simple soybeans, with their reduced digestibility, are so high in protein and in all the essential amino acids that they could still easily serve as the sole source of protein in a person's diet if that was necessary for some reason. "Soybeans also contain haemagglutinin," continue Fallon and Enig, "a clot-promoting substance that causes red blood cells to clump together. Trypsin inhibitors and haemagglutinin are growth inhibitors... Soy also contains goitrogens - substances that depress thyroid function." It is true that soybeans contain these substances. But there is little evidence that as a result soybeans represent a health danger to humans. Moderate amounts of soyfoods have been eaten happily by entire civilizations for thousands of years. Fallon and Enig's case is built on animal studies in which test animals fed extremely large amounts of soy containing these substances "failed to grow normally," and developed "pathological conditions of the pancreas, including cancer." ANIMAL STUDIES
Fallon and Enig make much of a 1985 study which showed that soy increases the risk of pancreatic cancer in rats. But researchers with the National Cancer Institute point out that the pancreas of a few species of animals, notably rats and chicks, are extraordinarily sensitive to dietary protease inhibitors such as those found in soy. This sensitivity has not been found in other species such as hamsters, mice, dogs, pigs, and monkeys, they say, and is "not expected to occur in humans." In fact, while rats fed nothing but soy run higher risks of pancreatic cancer, human populations consuming high levels of soy have decreased rates of pancreatic cancer. Species, even those that seem quite closely related, often function quite differently at a molecular level. It is true, as Fallon and Enig point out, that baby rats fail to thrive on soy. But they also fail to thrive on human breast milk. This is because rats and humans have vastly different requirements. Human milk, for example, is 5% protein; rats' milk is 45% protein. The difference in nutritional requirements and responses for different species can be enormous. Foods that are highly nutritious for one species are often inedible or even poisonous to other species. Fallon and Enig, however, build their case against soy upon animal studies. Soybeans are high in isoflavones - phytoestrogens, or plant substances that behave like weak forms of the hormone estrogen. K. O. Kline, M.D., of the Department of Clinical Science at duPont Hospital for Children in Delaware comments in a 1998 article in Nutrition Reviews. "It is clear from the literature," writes Kline, "that different species and different tissues are affected by (soy) isoflavones in markedly different ways." Fallon and Enig, however, do not agree. They denounce Kline's comments, fuming that "this is scientific double talk." To my eyes, in contrast, Kline's remark is the thoughtful humility of a scientist acknowledging the realities and limitations of animal research. Remember thalidomide, the drug that caused horrendous birth defects in children born to mothers who took the drug during their pregnancy? Thalidomide had been widely tested on animals, where it appeared to be totally safe. Similarly, the combination of fenfluramine and dexfenfluramine, recently touted to be the answer to dieters' prayers, was extensively tested on animals and found to be very safe. Unfortunately it caused heart valve abnormalities in humans. When the arthritis drug Opren was tested on monkeys, no problems were found, but it killed 61 people before it was withdrawn. Cylert was fine for animals, but when it was given to hyperactive children it caused liver failure. DOES SOY INHIBIT MINERAL ABSORPTION?
It is true that soybeans are high in phytates, as are many plant foods such as other beans, grains, nuts and seeds, and it is true that phytates can block the uptake of essential minerals, and particularly zinc. This would be a problem if a person consumed large amounts of phytates; for example, if they ate nothing but soybeans or wheat bran. But the phytic acid levels found in a plant-based diet including a serving or two of soy a day are not high enough to cause mineral absorption problems for most people eating varied diets. Furthermore, when soy products are fermented - as they are in tempeh, miso, and many other soyfoods - phytate levels are reduced to about a third their initial level. Other methods of soy preparation such as soaking, roasting and sprouting also significantly reduce phytate content. While phytates can compromise mineral absorption to some degree, there is absolutely no reliable evidence that vegetarians who eat soyfoods "risk severe mineral deficiencies." The complete adequacy of vegetarian diets is now so thoroughly proven and documented that even the National Cattlemen's Beef Association has acknowledged the legitimacy of meatless diets. In an official statement, these representatives of the beef industry declared, "Well planned vegetarian diets can meet dietary recommendations for essential nutrients." The statement that vegetarians risk severe mineral deficiencies sounds frightening, but Fallon and Enig provide no supporting documentation. The statement that "zinc deficiency can cause a 'spacey' feeling that some vegetarians may mistake for the 'high' of spiritual enlightenment" is totally unsupported by any data whatsoever, and is devoid of any scientific basis. Without providing any supporting evidence, Fallon and Enig go on to say that "soyfoods block calcium and cause vitamin D deficiencies... The reason that Westerners have such high rates of osteoporosis is because they have substituted soy oil for butter, which is a traditional source of vitamin D...needed for calcium absorption." Actually, as Westerners have eaten less butter, they've replaced it with margarine which, like butter, are fortified with vitamin D. Why, then, do Westerners have such high rates of osteoporosis? We have become sedentary, plus we consume a highly processed, high-salt, high-animal protein diet. Study after study has found that the more animal protein you eat, the more calcium you lose. The calcium-losing effect of animal protein on the human body is not a matter of controversy in scientific circles. Researchers who conducted a recent survey of diet and hip fractures in 33 countries said they found "an absolutely phenomenal correlation" between the percentage of plant foods in people's diets, and the strength of their bones. The more plant foods people eat (particularly fruits and vegetables), the stronger their bones, and the fewer fractures they experience. The more animal foods people eat, on the other hand, the weaker their bones and the more fractures they experience. What, then, about Fallon and Enig's assertion that Westerners have such high rates of osteoporosis because they have substituted soy oil for butter, and as a result no longer consume enough vitamin D for calcium absorption? Vitamin D is indeed needed for calcium absorption. But skin exposure to sunlight is the primary source of vitamin D in humans. In fact, people whose skin is not exposed to direct sunlight have difficulty getting enough vitamin D from their diets without supplementation. A 1999 report in the American Journal of Clinical Nutrition said that blood levels of vitamin D in sunlight-deficient people don't begin to rise until 4,000 units of vitamin D are consumed. Someone relying on butter for this amount would have to eat four pounds of butter a day. The data simply provide no basis whatsoever for blaming the osteoporosis rates in Western culture on the decrease in butter consumption. They do, however, point a definite finger at animal protein consumption, which helps explain the reduced rates of osteoporosis in people consuming soyfoods. DOES SOY PROTECT AGAINST HEART DISEASE?
The American Heart Association published a major statement officially recommending the inclusion of 25 grams or more of soy protein, with its associated phytochemicals intact (i.e., not in the form of an isolated soy protein supplement), in the daily diet as a means of promoting heart health. This recommendation is consistent with the FDA's recent ruling allows soy protein products to carry the health claim: "25 grams/day of soy protein, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease." What do the soy pooh pooh-ers say to this? They say that lowered cholesterol levels, even those lowered by diet, are dangerous. "Studies in which cholesterol levels were lowered through either diet or drugs," claim Fallon and Enig, "have consistently resulted in a greater number of deaths in the treatment groups than in controls." To document this remark, which is entirely unsupported in the scientific literature, the authors provide a footnote to an article written by themselves. Elsewhere they write: "The truth is that cholesterol is your best friend... When cholesterol levels in the blood are high, it's because the body needs cholesterol... There is no greater risk of heart disease at cholesterol levels of 300 than at 180." That's quite a point of view, ignoring as it does nearly everything that has been learned about heart disease and cholesterol in the past 30 years by medical science. The Lipid Research Clinics Coronary Primary Prevention Trial, considered the broadest and most expensive research project in medical history, said that the study proved that even small changes in our blood cholesterol levels produce dramatic changes in heart disease rates. Charles Glueck, M.D., director of the University of Cincinnati Lipid Research Center, one of the twelve major centers participating in the project, noted: " For every one percent reduction in total blood cholesterol level, there is a two percent reduction of heart disease risk." DOES SOY PROTECT AGAINST CANCER?
In 1997, the American Institute for Cancer Research, in collaboration with its international affiliate, the World Cancer Research Fund, issued a major international report, Food, Nutrition and the Prevention of Cancer: A Global Perspective. This report analyzed more than 4,500 research studies, and its production involved the participation of more than 120 contributors and peer reviewers, including participants from the World Health Organization, the Food and Agriculture Organization of the United Nations, the International Agency on Research in Cancer, and the U.S. National Cancer Institute. In 2000, Riva Bitrum, the President of Research for the American Institute for Cancer Research, said that "Studies showing consistently that just one serving a day of soyfoods contributes to a reduction in cancer risk are encouraging. Consuming one serving of soyfoods is a step most individuals would not find too difficult to take." Of course, any foods with such potent biological properties - even healthful ones - are bound to have some unwanted side effects in some people under some circumstances. Although soy consumption on the whole reduces cancer incidence, there are questions about its effect on women who have estrogen-positive (ER+) breast tumors. These tumors are stimulated by estrogen. Might they therefore be stimulated by the weak estrogenic activity of the isoflavones found in soy? There is some evidence this may be the case, though there is also evidence that soy consumption favorably alters the metabolism of estrogen so that it is less likely to stimulate tumor growth. At this point, given the uncertainty, women with ER+ breast cancer should probably avoid eating more than three or four servings of soy a week. For healthy women, according to the American Institute for Cancer Research, "even two or three servings a day of soyfoods should be fine as one part of a mostly plant-based diet." Soy supplements are a different story. Soy pills and powders can contain amounts of isoflavones (usually daidzein and genistein) far in excess of the amounts possible to get through diet. Very little research has been done on the effects of such mega-doses. Although there is no firm evidence to demonstrate that ingestion of isoflavones has adverse effects on human beings, there is also no clear evidence that large doses are safe. When manufacturers of soy protein isolates and supplements recommend that people consume 100 grams of soy protein a day (the equivalent of 7 or 8 soyburgers), they are ignoring the unknown effects of overdosing on isoflavones. I believe it's probably safer, until more is learned, to avoid concentrated soy supplements entirely. DOES SOY CAUSE BIRTH DEFECTS?
We certainly need more studies to determine what is going on, but after reading the actual study I am not nearly as concerned as I was upon reading Fallon and Enig's description, because what they neglect to mention is the significant fact that the total number of baby boys in the study born with this condition to vegetarian mothers was only seven. And it was not just vegetarian women who were found to be at greater risk for delivering a boy with hypospadias. Women who took iron supplements during pregnancy, and women who had the flu during the first trimester, also were at heightened risk. It's hard to know just what to make of this isolated study. To my eyes, it highlights how much we have yet to learn about the impact of the phytoestrogens contained in soy. Given our current state of knowledge, I think that pregnant women should largely avoid soy-based supplements. But there is no cause to conclude that vegetarian diets, or soyfoods, are suspect in pregnancy. DOES SOY CAUSE ALZHEIMER'S?
Other scientists were not so sure just what was going on here. If tofu consumption increased Alzheimer's incidence, then there would be more Alzheimer's in Japan than in Hawaii, because more tofu is eaten in Japan. But in fact the reverse is true. What, then, could have been the cause of the findings? People with Alzheimer's disease characteristically have higher levels of aluminum in their brains. Many studies have shown a link between increased levels of aluminum consumption and risk of Alzheimer's disease. Higher levels of aluminum in drinking water, for example, typically produce higher rates of the disease. When a physician practicing in Hawaii, Bill Harris, subsequently had soy products made in Hawaii and those from the mainland tested for their aluminum levels, the levels of aluminum in the Hawaii products were found to be significantly higher. Could it be that it is aluminum - used in the refining of some soy products in Hawaii - that is the actual culprit? No other study to my knowledge has ever found a link between soy consumption and Alzheimer's, but dozens of studies have supported the link between aluminum and the disease. INFANT SOY FORMULAS: BIRTH CONTROL PILLS FOR BABIES?
In my view, there is some basis here for concern. For an adult to regularly eat soy characteristically produces a reduced risk of developing breast or prostrate cancer. But the same phytoestrogens that produce this effect in adults may produce very different effects in infants. "With adults, half their phytoestrogens are freed into the bloodstream to bind to estrogen receptors, which helps to fight breast cancer," explains Patricia Bertron, dietician director of the Physicians Committee for Responsible Medicine. "But with infants, less than five percent are available to bind to receptors." There is a possibility that this could pose a risk to the sexual development of infants and children. Because the milk source makes up nearly the entire diet of infants, babies fed soy formulas may be at increased risk of harm. These theoretical risks are quite disturbing, but they appear at this point to be merely theoretical, because we have yet to see any substantive evidence of this harm in people. It is striking that there have been no reports of hormonal abnormalities in people who were fed soy formula as infants - and this includes millions of people in the past 30 years. In fact a major study published in the August, 2001, Journal of the American Medical Association found that infants fed soy formula grow to be just as healthy as those raised on cow's milk formulas. If the phytoestrogens in soy were affecting the reproductive system of infants fed soy formulas, then soy-fed babies would develop reproductive health problems as adults. The study evaluated 811 men and women between the ages of 20 and 34 who had participated in soy and cow's milk studies as infants. No significant differences were found between the groups in more than 30 health areas. The major exception was that women who had been soy-fed reported slightly longer menstrual periods (one-third of a day) than women raised on cow's milk formulas. The debate as to which is better, formulas based on soy or cow's milk, is unresolved. Each seems to have its own dangers. What is indisputable is that babies reared on breastmilk have tremendous health advantages over babies reared on any type of formula. Yet the anti-soy crusader Sally Fallon would evidently prefer that an infant be fed a cow's milk formula rather than breastmilk, if the mother is a vegetarian. She writes that "breast milk is best IF the mother has consumed a ...diet...rich in animal proteins and fat throughout her pregnancy and continues to do so while nursing her child." Why would someone make a statement like that? Where are these soy antagonists coming from? What are they trying to prove? Fallon and Enig are proponents of the philosophy that in order to be healthy people must eat large amounts of saturated fat from animal products. They insist that only with the regular consumption of lard, butter and other full fat dairy products, and beef, can people derive the nutrients they need to be healthy. They deplore the fact that soy products are increasingly replacing animal products in the American diet. Many of the most vocal soy bashers are of similar dietary persuasions. Joseph Mercola, for example, a Chicago osteopath who has authored a series of vehemently anti-soy articles that have circulated widely on the internet, is an ardent advocate of eating beef, chicken, turkey, ostrich, and other meats. FRANKENSOY?
Does eating genetically engineered soybeans pose potential health risks to people? In 2001, the Los Angeles Times published an exposé revealing that Monsanto's own research had raised many questions about the safety of their Roundup Ready soybeans. Remarkably, the FDA did not call for more testing before allowing these soybeans to flood the marketplace. Since half the soybeans grown in the United States are now Monsanto's Roundup Ready variety, and because soy is contained in such a wide array of processed foods, tens of millions of people are unknowingly eating these experimental foods daily. According to Monsanto's own tests, Roundup Ready soybeans contain 29 percent less of the brain nutrient choline, and 27 percent more trypsin inhibitor, the potential allergen that interferes with protein digestion, than normal soybeans. Soy products are often prescribed and consumed for their phytoestrogen content, but according to the company's tests, the genetically altered soybeans have lower levels of phenylalanine, an essential amino acid that affects levels of phytoestrogens. And levels of lectins, which are most likely the culprit in soy allergies, are nearly double in the transgenic variety. I find it fascinating that compared to regular soybeans, the genetically engineered beans have more of the very things that are problematic, and less of the very things that are beneficial. To my eyes, this is certainly another reason to eat organic foods whenever possible. The best way to insure that any soyfoods you eat are not genetically engineered is if they are organically grown. WHITHER THE JOY OF SOY?
The hype has also made us forget something important. We are eating soy products today at levels never before seen in history. Advances in food technology have made it possible to isolate soy proteins, isoflavones, and other substances found in the bean, and add them to all kinds of foods where they've never been before. The number of processed and manufactured foods that contain soy ingredients today is astounding. It can be hard to find foods that don't contain soy flour, soy oil, lecithin (extracted from soy oil and used as an emulsifier in high-fat products), soy protein isolates and concentrates, textured vegetable protein (TVP), hydrolyzed vegetable protein (usually made from soy) or unidentified vegetable oils. Most of what is labeled "vegetable oil" in the U.S. is actually soy oil, as are most margarines. Soy oil is the most widely used oil in the U.S., accounting for more than 75 percent of our total vegetable fats and oils intake. And most of our soy products are now genetically engineered. This has never before been done in human history. It is an experiment, and should be undertaken, if at all, with great humility, watchfulness, and caution. Instead, under the influence of an almost mystical belief in soy's virtues, we've tended to fall prey to an illusion that has haunted American culture in all kinds of ways - the illusion that if a little is good, then surely more must be better. The anti-soy crusaders, on the other hand, point to certain substances found in soy, and tell us that almost any amount of soy is too much. The reality, though, is all foods contain substances that, if eaten in high enough concentrations, would cause problems. Even the most healthful foods contain components that produce unwanted effects when they are tested in isolation in a laboratory. For example, broccoli, lentils, and grapefruit contain naturally occurring pesticides that can cause mutations if eaten in high enough quantities. Peanuts and peanut butter often have traces of aflatoxin, a substance found in a mold that grows on the nuts that causes cancer in high enough amounts. Celery harbors toxins that at high enough levels damage the human immune system and causes photosensitivity. (Highest levels occur in celery that has brownish patches.) Spinach and chard contain oxalic acid, a substance which binds with calcium and diminish its absorption. Common mushrooms contain several substances that in sufficient concentrations are carcinogens. If you made it your policy to eat no food that contained substances which can in large enough concentrations cause damage, there would be literally nothing left for you to eat. In my view, the best way to take advantage of soy's health benefits is to follow the example of the traditional Asian diets and stick with whole foods. As a population, these are cultures that, when they have eaten their traditional diets, have tended to be healthier and live longer than Americans. The Okinawa Japanese, the longest living people in the world, average 1-2 servings of soy each day. They have traditionally eaten regular but moderate amounts of whole soyfoods such as tofu, soymilk, and edamame, as well as the fermented versions, tempeh, tamari, and miso. These are the soyfoods that I prefer to eat - rather than the soy products made with soy protein iso |
I've received quite a number of requests from people asking for my views on soy products. Many of these inquiries have mentioned a stridently anti-soy article written by Sally Fallon and Mary G. Enig, titled "Tragedy and Hype," that has been widely circulated. This article presents a systematic series of accusations against soy consumption, and has formed the basis for many similar articles. Large numbers of people, as a result, are now seriously questioning the safety of soy.