Categories: Soy

What About Soy?

Over the past months, 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. The litany of dangers with soy products, according to the article by Fallon and Enig, is nearly endless. Tofu, they say, shrinks brains and causes Alzheimer’s. Soy products promote rather than prevent cancer. Soy contains “antinutrients” and is full of toxins. The pro-soy publicity of the past few years is nothing but “propaganda.” Soy formula, they say, amounts to “birth control pills for babies.”

“Soy is not hemlock,” they conclude, “soy is more insidious than hemlock.” Fallon and Enig say the soy industry knows soy is poisonous, and “lie(s) to the public to sell more soy.” They say that soy is “the next asbestos,” that there will be huge lawsuits with “thousands and thousands of legal briefs,” and that those who will be held legally responsible for deliberately manipulating the public to make money “include merchants, manufacturers, scientists, publicists, bureaucrats, former bond financiers, food writers, vitamin companies, and retail stores.” Given the rapidly expanding role that soy in its many forms has come to play in the Western diet, these accusations are extremely serious. If they are to be believed, the widespread trust that many people have come to have in soy is not only misplaced, but disastrous.


It’s not that long ago that soybeans were considered by most Americans to be “hippie food.” But then medical research began accumulating, affirming that soy consumption reduced heart disease and cancer risk, that it lengthened lives and enhanced their quality, and that it provided an almost ideal protein to substitute for animal proteins that almost inevitably come packaged with cholesterol and saturated fat. The mainstream culture began taking note. In a 1999 article titled “The Joy of Soy,” Time Magazine announced that a mere 1.5 ounces of soy can lower both total and LDL (“bad”) cholesterol levels. The evidence was becoming so convincing that even the ardently pro-pharmaceutical FDA wound up affirming that soybeans are a food that can prevent and even cure disease.

As the evidence of soy’s health benefits kept accumulating, sales and consumption skyrocketed. Books like The Simple Soybean and Your Health, Tofu Cookery, and The Book of Tofu helped spread the word. Annual soy milk sales, which amounted to only a few million dollars in the U.S. 20 years ago, have now soared to hundreds of millions of dollars. 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 soy foods, 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 soy foods 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 are at the very foundation of many of the accusations against soy. But animals are not the same as humans, so foods that affect them in one way may well affect us differently. Protease inhibitors are substances that retard the action of digestive enzymes that cause the breakdown of protein. Fallon and Enig refer to studies that show that protease inhibitors isolated from soybeans can cause cancer in some animal species, but there is almost no evidence even suggesting that they have the same effect in humans. In fact, protease inhibitors found in soybeans appear to reduce the incidence of colon, prostate and breast cancer in humans.

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 value 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.


Fallon and Enig are adamant in their beef with soy, however, and their indictment of the bean continues. They fault soy for its phytic acid content. “Soybeans are high in phytic acid,” they say, “a substance that can block the uptake of essential minerals – calcium, magnesium, copper, iron and especially zinc in the intestinal tract… Vegetarians who consume tofu as a substitute for meat and dairy products risk severe mineral deficiencies… Phytates found in soy products interfere with zinc absorption more completely than with other minerals. Zinc deficiency can cause a ‘spacey’ feeling that some vegetarians may mistake for the ‘high’ of spiritual enlightenment.”

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 soy foods – 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 soy foods”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.

Let’s look, one by one, at the minerals Fallon and Enig claim to be lacking for vegetarians.

Zinc: It is wise for vegetarians to include plenty of zinc-rich foods in their diets, but the levels of zinc found in the hair, saliva, and blood of vegetarians are typically in the normal range. Zinc deficiency would be particularly harmful in pregnant women, but studies of pregnant women have consistently found no difference in zinc status between vegetarians and nonvegetarians.

Iron: Vegetarian diets are much higher in vitamin C, and vitamin C greatly enhances iron absorption, so even without eating red meat (which is high in iron), and even with the reduction in iron absorption from phytates, vegetarians are no more prone to iron deficiency than are nonvegetarians.

Copper: Vegetarian diets tend to be higher in copper, which overrides any reduced rate of absorption from phytates. Vegans, in particular, consume considerably more copper than meat-eaters.

Magnesium: Although the higher phytate content of soybeans and grains slightly reduces magnesium absorption, vegetarians diets are typically so much higher in this crucial mineral that vegetarians consistently show markedly higher serum magnesium levels than do nonvegetarians.

Calcium: Calcium from soy is nearly as bioavailable as calcium from cow’s milk. Hundreds of studies have found vegetarians in the West to have healthier bones, more positive calcium balance and less osteoporosis than meat-eaters – as well as less heart disease, cancer, high blood pressure, obesity, and diabetes, and substantially longer lifespans. Without providing any supporting evidence, Fallon and Enig go on to say that “soy foods 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 margarines 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.

Similarly, in January 2001, the American Journal of Clinical Nutrition published a study that reported a dramatic correlation between the ratio of animal to vegetable protein in the diets of elderly women and their rate of bone loss. In this seven-year study funded by the National Institutes of Health, more than 1,000 women, ages 65 to 80, were grouped into three categories: those with a high ratio of animal to vegetable protein, a middle range, and a low range. The women in the high ratio category had three times the rate of bone loss as the women in the low group, and nearly four times the rate of hip fractures.

Might this have been due to other factors than the ratio of animal to vegetable protein? According to the study’s lead author, Deborah Sellmeyer, MD, Director of the Bone Density Clinic at the University of California, San Francisco, Medical Center, researchers found this to be true even after adjusting for age, weight, estrogen use, tobacco use, exercise, calcium intake, and total protein intake. “We adjusted for all the things that could have had an impact on the relationship of high animal protein intake to bone loss and hip fractures,” Sellmeyer said. “But we found the relationship was still there.”

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 soy foods.


If the articles written and spawned by Fallon and Enig were to be believed, just about everything we’ve been taught to believe about soy’s benefits is completely backwards. What about soy’s vaunted reputation (and FDA approval) for bringing down cholesterol levels? “For most of us,” say Fallon and Enig, “giving up steak and eating veggieburgers instead will not bring down blood cholesterol levels.” The kernel of truth in Fallon and Enig’s statement is that soy consumption tends to bring down total cholesterol levels most in people whose cholesterol levels are high. But even people with normal levels benefit from eating more soy, according to dozens of studies, because it improves the ratio between HDL (good) and LDL (bad) cholesterol. This ratio is now recognized by the American Heart Association to be an even more important factor than total cholesterol levels in heart disease risk.

In 2000, the Nutrition Committee of the American Heart Association published a major statement in the peer-reviewed journal Circulation, 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 allowing 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, for example, is considered the broadest and most expensive research project in medical history. Sponsored by the federal government, it took over ten years of systematic research, and cost over $150,000,000. George Lundberg, MD, the editor of the Journal of the American Medical Association, where the gargantuan study was first published, said that the study proved that even small changes in our blood cholesterol levels produce dramatic changes in heart disease rates. Charles Glueck, MD, 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.”


What about soy and cancer? Is there anything to the allegations coming from the anti-soy camp that soy consumption causes cancer? Such charges are certainly incompatible with the findings of the prestigious Health Professionals Follow-up Study, which found a 70% reduction in prostate cancer for men who consume soymilk daily.

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 soy foods contributes to a reduction in cancer risk are encouraging. Consuming one serving of soy foods 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 soy foods 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.


One of the most alarming allegations in the Fallon and Enig article is that, due to the phytoestrogens in soy foods, vegetarian diets promote birth defects. They repeatedly refer in the article and elsewhere to a study published in the British Journal of Urology that found baby boys born to vegetarian mothers were five times more likely to suffer from hypospadias, a malformation of the penis correctable with surgery. I found this disturbing, and somewhat difficult to believe, because I know of no other study that links vegetarian diets with a higher rate of any birth defect, including hypospadias, and there are a number that show the opposite – lower rates of a variety of birth defects in babies born to vegetarian mothers. If the findings of this study were valid, however, it would be extremely important.

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 soy foods, are suspect in pregnancy.

Vegetarian diets have consistently shown profound benefits for pregnancy and lactation, including much lower levels of the toxic chemicals that typically concentrate higher on the food chain in meat, fish and dairy products. A report in the New England Journal of Medicine on the levels of contamination in human breastmilk found that vegan mothers had dramatically lower levels of toxic chemicals in their milk compared to mothers in the general population. The highest level seen among these vegan mothers was actually lower than the lowest level seen in nonvegetarian mothers. In fact, the levels of contamination found in the milk of the vegetarian mothers was only 1 to 2 percent as great as the level found in the milk of nonvegetarians.


“Tofu Shrinks Brain,” shouted the headlines of a tidal wave of articles emanating from the anti-soy camp in recent years. The basis for the excitement were discoveries made in the Honolulu Heart Program, an ongoing study of the health of Japanese-American men living in Hawaii. It seems that those who consumed the most tofu (two to four times a week) during middle age showed the most signs of mental deterioration in later years, including greater incidence of Alzheimer’s disease. This was startling, because high cholesterol levels have long been intimately linked to increased risk for Alzheimer’s, and soy has been shown repeatedly to lower cholesterol levels. The researchers who conducted the study, led by Lon White, believe the negative effect could stem from the hormonal effects of the isoflavones found in soy. 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.

While the anti-soy crusaders have been claiming, based on this single isolated study, that soy causes a decrease in cognitive function, students at Bay Point Schools in South Miami-Dade County, Florida, have been having a very different experience. This is an alternative year-round residential public school for students 13 to 18. Most of the kids are sent to this school by the court system after committing offenses. Many come from the streets, and their academic achievement typically is low. But many of them are finding an experiment with vegetarianism could be the recipe for success. The school’s culinary arts program challenges the kids to be vegans for a month, and the achievements have been stunning, with students in the program reporting boosts in both their grades and their energy. “I came in here with a 1.6 (grade-point average). That’s not even a passing grade.

At this point I’ve got a 3.4,” said Willie Williams, who admits that at first he was skeptical of the tofu. But Willie, who plays both basketball and football, soon noticed an improvement both in the classroom and on the court and field. “I’m considering doing this for a long time, just make it a constant thing,” he says. He’s not alone. Kovanic Capron, 17, saw his grade point average improve from 3.1 to 3.9. The brain-boosting powers of soy were evident in that not a single one of the students enrolled in the program scored below 85 on the final exam. And the students say that eating this way has them devouring the competition in school sports. “I used to get tired when I ran laps or lifted weights,” said Gabriel Saintvil, 18. “Now I get endurance and keep on doing it.”


Another of the disturbing charges made by the soy bashers is the allegation that “an infant exclusively fed soy formula receives the estrogenic equivalent (based on body weight) of at least five birth control pills per day.” Soy formula, say Fallon and Enig, amounts to “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. Compared to babies who are fed soy or cow’s milk based formulas, babies who are beast-fed for at least six months have three times fewer ear infections, five times fewer urinary tract infections, five times fewer serious illnesses of all kinds, seven times fewer allergies, and are fourteen times less likely to be hospitalized. Babies who are breastfed spit up less often, have less diarrhea and less constipation. For every 87 formula-fed babies who die from Sudden Infant Death Syndrome, only three breastfed babies die from the disease. Babies who are fed only human milk for at least six months are six times less likely to develop lymphoma, a cause of cancer, in childhood. Babies breastfed for at least one year are only half as likely to develop diabetes. Children who were fed human milk have an average IQ seven points higher.

As adults, people who were breastfed have less asthma, fewer allergies, less diabetes, fewer skin problems including dermatitis, lower risks of heart attacks and stroke due to lower cholesterol levels, less ulcerative colitis (ulcers in the large intestines), less Crohn’s disease, and protection from certain chronic liver diseases. The indisputable advantages of breastfeeding apply to mothers, too, affording major reductions of breast cancer risk. Yet working mothers wanting to breastfeed are often faced with a formidable challenge, because few workplaces have daycare facilities for their workers or allow for breastfeeding breaks. In 1998, New York Representative Carolyn Maloney sought to change that, introducing a bill in Congress that would provide a mandated daily one hour of unpaid leave for expressing breast milk, plus provide incentives for employers who created a “lactation-friendly” environment.

The evidence that breast is best is overwhelming. Infants breastfed by vegetarian mothers have all these advantages, plus more, because the milk of vegetarian mothers has the added advantage of harboring substantially fewer residues from pesticides and other toxic chemicals. 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.


Other anti-soy crusaders, most notably the U.S. dairy industry, clearly have a financial agenda. In recent years, the dairy industry has been waging war against soymilk. They have attempted to keep soy beverages from being included in the milk group in the Dietary Guidelines for Americans. They have sued the manufacturers of soy beverages for using the word milk, claiming that the dairy industry alone has a right to use the term. And they have tried to keep soy beverages from being sold alongside cow’s milk in the grocery aisles. A spokesperson for the National Milk Producers Federation made it clear why the industry was upset. “It is,” he said, “a clear attempt to compete with dairy products.”

Meanwhile, the dairy industry spends hundreds of millions of dollars on ads and other forms of promotion trying to convince the public that cow’s milk is vastly preferable to soy milk. For example, the Dairy Bureau tells you about the nutritional comparison between cow’s milk and soy milk. “Unfortified soy beverages,” they say, “contain only half of the phosphorus, 40 percent of the riboflavin, 10 percent of the vitamin A, (and) 3 percent of the calcium . . . found in a serving of cow’s milk.” Let’s look at this carefully for a moment.

Only half the phosphorus? Brenda Davis is a registered dietitian and former Chair of the American Dietetic Association’s Vegetarian Practice Group. She is not impressed by the dairy industry claims. “We get plenty of phosphorus in the diet,” she says, “and possibly even too much. Providing only half the phosphorus of cow’s milk is an advantage, not a disadvantage.” Only 40 percent of the riboflavin? It’s true that unfortified soy milks contain only about half as much of this nutrient as cow’s milk, but riboflavin is plentiful in nutritional yeast and green leafy vegetables, and is found in nuts, seeds, whole grains, and legumes, so getting enough riboflavin isn’t a problem for people who eat a variety of healthy foods. In fact, vegans (who consume no dairy products) consume as much, or nearly as much, of this vitamin as lacto-ovo vegetarians and non-vegetarians. A mere teaspoon of Red Star Nutritional Yeast powder contains as much riboflavin (1.6 mg) as an entire quart of cow’s milk.

Only 10 percent of the vitamin A? Vitamin A is plentiful in plant-based diets. We don’t need milk to get sufficient amounts of this nutrient. In fact, vitamin A deficiency is quite rare among North Americans and Europeans who eat plant-based diets. Furthermore, vitamin A is high in cow’s milk only because it’s added to it, and there is no reason it could not be added to non-dairy beverages if there was some advantage to doing so.

Only 3 percent of the calcium provided by cow’s milk? Where does the dairy industry come up with this stuff? All of the most popular soy beverages sold in the United States provide vastly more calcium than the 3 percent claimed by the Dairy Bureau. Westsoy Plus provides 100 percent as much; Vitasoy Enriched provides 100 percent as much; Pacific Soy Enriched provides 100 percent as much; and Edensoy Extra provides 67 percent as much. Even those soy beverages that have not been enriched provide two to nine times as much calcium as claimed by the Dairy Bureau.

Meanwhile, there are a few more things the dairy industry isn’t telling you about the nutritional comparison between cow’s milk and soy milk. For example:

  • Cow’s milk provides more than nine times as much saturated fat as soy beverages, so is far more likely to contribute to heart disease. Soy beverages provide more than 10 times as much essential fatty acids as cow’s milk, and so provide a far healthier quality of fat.
  • Soy beverages are cholesterol-free, while cow’s milk contains 34 mg of cholesterol per cup, which again means that cow’s milk is far worse for your heart and cardiovascular system. Soy beverages lower both total and LDL (“bad”) cholesterol levels, while cow’s milk raises both total and LDL cholesterol levels, providing yet more reasons soymilk is better for your health.
  • Soy beverages contain numerous protective phytochemicals that may protect against chronic diseases such as heart disease and osteoporosis. Cow’s milk contains no phytochemicals.
  • Men who consume one to two servings of soymilk per day are 70 percent less likely to develop prostate cancer than men who don’t. FRANKENSOY?

There are legitimate questions about soy. One of the most recent, and most disturbing, stems from the fact that two-thirds of the U.S. soybean crop today is genetically engineered. These are beans that have been genetically altered to enable the growing plants to withstand being sprayed with weedkillers, particularly Monsanto’s Roundup. Because so much Roundup is used on these crops, the residue levels in the harvested crops greatly exceed what until very recently was the allowable legal limit. For the technology to be commercially viable, the FDA had to triple the residues of Roundup’s active ingredients that can remain on the crop. Many scientists have protested that permitting increased residues to enable a company’s success reflects an attitude in which corporate interests are given higher priority than public safety, but the increased levels have remained in force.

Does eating genetically engineered soybeans pose potential health risks to people? In 2001, the Los Angeles Times published an expos 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 soy foods you eat are not genetically engineered is if they are organically grown.


While soy foods have much to offer, they have certainly been at times heavily over-promoted. As a result, some people have gathered the impression that as long as they eat enough soy, they don’t have to worry about the rest of their diet and lifestyle. This is a dangerous and mistaken belief. Just as taking vitamins can’t atone for a poor diet, taking soy can’t make up for a diet that’s otherwise high in calories, saturated fat, and junk food. Nor can it compensate for a lack of exercise, or other destructive lifestyle habits.

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. This doesn’t mean, though, that you should avoid eating broccoli, lentils, grapefruit, peanut butter, celery, spinach, chard and mushrooms. In fact, 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.

It’s true that soybeans contain substances that in excess can be harmful. But to imply, as some do, that as a result eating soy foods poses a risk to human health is taking things much further than the evidence warrants. There would be dangers in eating a diet based entirely on soybeans. But, then, the same could be said for broccoli or any other healthy food. This is one of the reasons why varied diets are so important. Diversity protects. For most people under most circumstances, soy products are a healthful addition to a balanced diet that includes plenty of vegetables, whole grains, seeds, nuts, fruits, and other legumes. For most people, substituting soy foods for some of the animal foods they now eat is one of the healthiest dietary changes they could make.

What, then, would be a healthy relationship to soy in the diet? Are some forms of soy healthier than others? 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 soy foods such as tofu, soymilk, and edamame, as well as the fermented versions, tempeh, tamari, and miso. These are the soy foods that I prefer to eat – rather than the soy products made with soy protein isolates, soy protein concentrates, hydrolyzed soy protein, partially hydrogenated soy oil, etc.. Whole soy foods are more natural, and are the soy foods that have nourished entire civilizations for centuries.

For me, the best of the bean includes foods like:

Tofu, soaked and cooked soybeans that are made into a custard-like curd. The soaking process used traditionally to make tofu reduces the trypsin inhibitors and phytates. High in protein, tofu has a bland and neutral taste, and can be added to all kinds of foods. As with all soy products, get organic if you can. Tempeh, a fermented soybean cake with a nutty, mushroom flavor and chewy texture. Extremely high in protein and fiber, and produced in a way that greatly lowers trypsin inhibitors and phytates, tempeh is, from a nutritional perspective, an ideal way to eat soybeans.

Miso, a paste made from cooked soybeans that are fermented with rice or other grains. Widely used as a salty condiment and a basis for soups, miso is a potent probiotic, containing many kinds of friendly bacteria that are beneficial to the intestinal tract. The fermentation process used to make miso deactivates the trypsin inhibitors and phytates. Tamari (or Shoyu), a fermented soysauce that is very flavorful and salty Soymilk, made from soaked, ground soybeans, and increasingly used in the U.S. as a substitute for the milk of cows. Often called soy “beverages,” or soy “drinks,” because the dairy industry refuses to allow them to use the word “milk.” Trypsin inhibitors and phytates are low. I prefer the brands made with whole soybeans, and avoid those made with soy protein or soymilk powder. (There are also milks made from rice, almonds and oats that offer their own advantages to cow’s milk.)

Soy Nuts and Soy Nut Butter, a particular favorite with many children. Roasting helps reduce phytate levels. Edamame, a green vegetable soybean harvested while immature, so that the seeds fill 80% to 90% of the pod. Cooked for about 15 minutes in lightly salted boiling water, it’s served as a snack, mixed with vegetables, or added to salads or soups. Soy ice creams (non-dairy frozen desserts) may not technically belong on a list of the healthiest of ways to eat soy, but I’ve got a weakness for them. I eat the ones made with organic beans and/or organic soymilk, not those (like Tofutti) made with soy proteins or soy protein isolates. (As with soymilk, there are frozen desserts made from rice and other plant foods that also offer advantages to cow’s milk ice cream.)

There are legitimate questions about certain soy foods, and much we have yet to learn. Becoming soy-a-holics and automatically downing anything made from soybeans is not the road to health, but neither is shunning and stigmatizing soy foods The anti-soy crusade has needlessly frightened many away from a food source that has long been a boon to humankind, a food source that can, if we are respectful of our bodies and of nature, nourish and bless us in countless ways.

Author: John Robbins