
As someone who is conscious of her health, I spent years cultivating a vegetarian diet that included enough protein to fuel my busy lifestyle. I knew products made from soybeans were high in protein and a good source of B vitamins, so I strove to eat soy daily — soymilk, soy yogurt, tofu, soy hot dogs, you name it. I usually avoided products with ingredients I could not pronounce, but if they were attached to soy, I let it slide. Soy protein isolate? Great, I thought to myself. They’ve isolated the protein from the soybean to make it more concentrated. Hydrolyzed soy protein? Sure.
Now, admittedly, I didn’t find good rationalizations for all the soy-based products I consumed, but I wasn’t too worried. After all, in 1999 the Food and Drug Administration (FDA) approved labeling that designated soy products as “heart healthy.” Soy ingredients weren’t only safe — they were beneficial.
After more than a decade of consuming various forms of soy, I felt reasonably fit, but in 2005, I stopped menstruating. I was just 29 years old. I couldn’t figure out why my stomach was so upset after I ate edamame or why I was often moody and bloated. It didn’t occur to me at the time to question soy, the sanctioned heart protector and miracle food.
I’ve had a lifelong interest in how food affects health, and so, in my early 30s, I decided to become a certified nutrition consultant specializing in holistic health. In my classes, I kept running across studies that talked about the wide range of risks associated with eating soy: endocrine disruption, digestive problems, infertility, decreased sex drive — and even the potential to contribute to certain cancers. As I began to learn about these potential dangers, I began wondering why no one was talking about the subject in the popular press or health media.
According to Kaayla Daniel, PhD, a certified clinical nutritionist and author of The Whole Soy Story: The Dark Side of America’s Favorite Health Food (New Trends, 2005), the FDA pushed the health benefits of soy despite massive evidence to the contrary — and against the protests of its top scientists. The motive: pure profit.
To prove the point, Daniel points to the marketing patterns of certain agribusinesses, such as Dean Foods, which produces Silk soymilk. “Soy is a multibillion-dollar U.S. industry that’s taken these health claims to the bank,” she says. Once considered a small-scale poverty food in the United States, soy sales have exploded, increasing from $1 billion to $5.2 billion in sales from 1996 to 2011. “The soy industry has come a long way from when hippies were boiling up the beans,” says Daniel.
That’s an understatement. These days, soy is everywhere in our food supply. Even if you don’t drink soymilk or eat tofu, chances are you are still consuming soy routinely — in many cases, daily. Soybean oil has become the base for most vegetable oils; soy lecithin, the waste product left over after the soybean is processed, is used as an emulsifier; soy flour appears in baked and packaged goods; different forms of processed soy protein are added to everything from veggie burgers to muscle-building protein powders to animal feed. And let’s not forget the “milk,” promoted as the perfect dairy alternative for vegans or the lactose intolerant. Soy’s ubiquity — along with the conventional mindset that if a little is good, more must be better — has led to overconsumption, and as with many foods, too much can cause problems.
The debate over soy continues. In 2006, the FDA announced it was reevaluating the evidence in support of its 1999 claim. But it stated that its decision to do so was not because the data no longer supports its earlier claim, but rather because so many studies on soy have been published since the claim was initially approved.
Processing Soy
Many epidemiological studies have shown that Asians, particularly in Japan and China, have a lower incidence of breast and prostate cancer than people in the United States, and several of these studies credit a traditional diet that includes soy. So, what gives?
As it turns out, Asian diets include only small amounts — on average, about 7 grams a day (picture a small serving of tofu) — of primarily fermented soy products, such as miso, natto (a strong-smelling sticky substance popular in Japan), tempeh and some types of tofu. Fermenting soy makes it easier to digest and creates health-promoting probiotics, the good bacteria our bodies need to maintain digestive and overall wellness.
By contrast, most of the soy consumed in the United States is both unfermented and processed. For example, soy-based snacks or shakes can contain more than 20 grams of soy protein in one serving, and folks who are lactose intolerant or vegan may chug many glasses of soymilk daily.
Up until about 10 years ago, soymilk was the main alternative to cow’s milk, says Elson Haas, MD, medical director of the Preventive Medical Center of Marin. Haas would like to see people choose “better options like milks made from almonds, rice, hemp, oats or hazelnuts.” (For more info about milk alternatives, see “The New Moo.”)
For the most part, says clinical nutritionist Ed Bauman, MEd, PhD, founder and president of Bauman College, eating foods in their most pure and unadulterated state is a good thing. Soybeans in and of themselves are not all bad, he says, but the processing of soybeans is another issue. “Once there was a bean,” says Bauman, “but then it got cooked and squeezed and the pulp was separated out, and it was heated and processed for better shelf life and mouth feel.”
Haas stresses that most people fare best when they consume fermented forms of soy. If it’s not fermented, the bean must be processed with solvents or chemicals to make it palatable, although the extent does vary. Soymilk and tofu are no longer considered whole foods, for example, since they have been separated from the bean. And these products are less processed than soybean oil or those ubiquitous soy proteins, such as soy protein isolate, hydrolyzed soy protein and textured vegetable protein (TVP), which are found in many processed and packaged foods.
Consider what it takes to produce soy protein isolate. The soybeans are heated and exposed to a solvent-extraction process (which often uses the chemical hexane, a known neurotoxin) to remove the oils. This defatted meal is mixed with another solution to remove the fiber, and then it is subject to an acid wash. The resulting curds are neutralized in an alkaline solution and spray-dried at high temperatures to produce a protein powder.
Again, says Bauman, this highly processed product is a far cry from whole soybeans or naturally fermented soy. “We’re looking at this whole processed-food convenience market and we’re making generalizations about a plant,” he says. “Is soy the problem, or is it the handling and packaging and processing of the plant that’s the problem?”
Soy Sensitivity
Haas says that soy is one of the foods most likely to cause allergic and other reactions, including digestive upset. And while most people equate food allergies with anaphylaxis or another severe immune response, it is possible to have a subclinical reaction, which can morph into a host of health problems over time.
For reasons scientists cannot fully explain, in fact, food allergies are on the rise, especially in children. The Centers for Disease Control and Prevention reports that food allergies in children increased 18 percent from 1997 to 2007. The top eight food allergens — milk, eggs, peanuts, tree nuts, fish, shellfish, soy and wheat — account for more than 90 percent of those food allergies and sensitivities.
One theory for the rise is referred to as the hygiene hypothesis, which posits that our zealous use of disinfectants and antibiotics is interfering with the natural development of our immune systems. Deprived of more opportunities to fight germs, bacteria and infections, the theory goes, our immune systems get confused and attack allergens in the environment or proteins in foods.
Overconsumption is also an issue. It’s a complex process, but basically the more we consume certain foods, the more our immune systems are put on alert and the more we become sensitive to them. And, says Bauman, genetically modified (GM) foods can be even more problematic. “People can develop sensitivity to a food that has antigens or bacteria not originally in the food chain, as is the case with GM foods.” Up to a staggering 91 percent of soybeans are genetically modified in the United States, according to the Center for Food Safety.
On occasion, negative reactions to the bean start in infancy when babies are fed soy-based infant formula. Symptoms can be as subtle as hives or colic or as severe as an anaphylactic response. In fact, when the FDA declared soy “heart healthy” in 1999, its analysis ignored the emerging risks of soy-based infant formula. In particular, the FDA failed to recognize a 1997 study in the journal The Lancet that showed that daily exposure to plant-based estrogens for infants consuming soy formula was six to 11 times higher than the dose that has hormonal effects in adults consuming soy foods. The National Institute of Environmental Health Sciences has since linked soy’s estrogenic effects with early onset of puberty in females and alterations in development of breast tissue.
As a general rule of thumb, Haas counsels people to eliminate soy from their diets if it is a concern. The most common symptoms Haas sees in people who don’t tolerate soy are gas and bloating, but they can be as wide ranging as eczema, runny nose and moodiness. “As with any potential allergen,” says Haas, “take a break from it and see if you feel better; then try it again and see if it produces any ill effects.” (For more on how to eliminate potential allergens from your diet, see “The UltraSimple Slimdown.”)
Soy and Hormones: Friends or Foes?
Even if you are not allergic to soy, Daniel cautions, you might do well to minimize consumption of highly processed soy-based foods. “The bottom line is that soybeans naturally contain plant estrogens, toxins and antinutrients, and you can’t completely remove those.”
Naturally occurring components found in soybeans, such as saponins, soyatoxin, phytates, protease inhibitors, oxalates and goitrogens, are called “antinutrients” because they basically block absorption of minerals and inhibit enzyme production needed for digestion. That’s one reason why they can cause stomach pain and bloating in some people. Goitrogens, in particular, interfere with iodine metabolism and, as a result, inhibit thyroid function.
“I have a lot of thyroid patients,” says Haas, “and I have them take their thyroid meds first thing in the morning. I tell them to avoid soy at breakfast, because soy may interfere with the way your body absorbs and utilizes the thyroid hormone. It’s not well documented, but it’s something many doctors see.”
Soy also contains plant-based estrogens called isoflavones. Studies on the effects of isoflavones on human estrogen levels are conflicting, and experts say it’s possible that they affect people differently. Some studies show that isoflavones can mimic the body’s own estrogens, which can cause symptoms such as weight gain and headaches in women. Conversely, other studies show that these same isoflavones can offer relief from perimenopausal and menopausal symptoms and may also block the body’s estrogens, which can help reduce high estrogen levels, therefore reducing risk for breast cancer or uterine cancer before menopause. Yet, still more studies show that soy’s isoflavones may also have the potential to promote hormone-sensitive cancers in some people.
Soy’s effects, says Haas, “are so individualized that you can’t take these widespread ideas and apply them to everyone.” In men, soy has been shown to lower testosterone levels and sex drive, according to both Haas and Daniel.
The highest risk of adverse exposure is for infants who drink soy-based formula. “It’s the only thing they’re eating, they’re very small, and they’re at a key stage developmentally,” says Daniel. “The estrogens in soy can affect the hormonal development of these children, adversely affecting their growing brains, reproductive systems and thyroids.”
Soy formula also contains large amounts of manganese, which has been linked to attention deficit disorder and neurotoxicity in infants. In 2005 the Israeli health ministry issued an advisory stating that infants should avoid soy formula altogether. Shortly after, the French Food Agency, German Institute of Risk Assessment and British Dietetic Association all followed suit, warning their citizens of the dangers associated with soy-based infant formula.
Despite the growing evidence that consuming soy can be risky — especially if it’s highly processed or genetically modified — most of our experts agree that small amounts of soy are just fine. Bauman, for example, suggests eating a variety of natural and seasonal unprocessed whole foods, including soy in moderation, tailored to individual biochemistry and sensitivities. (It is possible to obtain similar plant estrogens to a lesser extent from other foods, such as lima beans or flaxseed.)
And Daniel, Bauman and Haas all agree on the benefits of variety.
“My experience as a clinical nutritionist,” Daniel says, “is that people who have a varied diet tend not to get into trouble.”
Thank you for this detailed description about soy products, I came across it while searching for information about the effect of tofu on the gut, after having a small meal of tofu for lunch. In the evening my stomach became horribly distended with bloating, followed by diarrhoea. I have used soy milk and spread for many years and always have bloating. I laid the blame on prescribed medicines that I have to take. That tofu reaction got me wondering if soya milk has been the culprit all along. So from today it will be removed from my diet. Even if it doesn’t stop the bloating the information you have provided is enough reason to stop consuming it.
Very insightful and oh so helpful article that seems to give answers to the many questions I’ve been asking myself about my declining health. Many of my symptoms could be explained by my consumption of processed soy products. I’m a ‘vegatarian’ – the only animal product I consume is eggs. I really love soy milk and yoghurt but can’t wrap my mind around going back to cow’s milk. What other alternative is safe to eat every day? Is almond milk ok? Every day I read about good foods and bad foods and the list of good actually being bad keeps growing longer. What do you recommend?
Many thanks
Not a single thread of evidence linked her health condition to eating soy, just propagating others’ speculations. Here is hard evidence: In Taiwan and China, ten of millions of people drink soybean milk every day and eating various types tofu every day, and not a single person ever died from eating and drinking soy products daily. In Detroit, MI, alone, 16.2 persons per 100,000 residents died from traffic accidents per year. Do we stop driving?
Diet is never a one-size-fits-all-approach. One food may work well in one system and be detrimental to another. Soy happens to be one of the most ubiquitous government-subsidized foods (along with wheat & corn) in our food supply, and 90% of it is genetically engineered, the implications of which we don’t yet fully understand. Early studies, however, are showing stomach lesions and an increase in allergies and autoimmune issues in rats fed GMO-soy and corn.
Most people, even the health conscious, are not eating 100% clean, and even in “health foods,” it’s almost impossible to avoid soy in the food supply. The processing of soy increases its problematic estrogenic properties, giving soy protein isolates, for example, the potential to create problems. (On a related note, yes, flax has estrogenic properties, but are we drinking copious amounts of flax milk and using flax protein isolate in foods?)
That’s why we mention in the article that certain forms of soy, such as fermented, may be okay, and point out those which are processed. The food and soy industry’s spin on soy as a magic bullet meant a huge spike in processed soy products and supplements, and many people were (and are) relying on these foods as the base of their diets. Too much of anything so heavily processed can cause problems.
Bottom line: soy doesn’t work for everyone. Processed soy foods can be very detrimental. Whole unfermented soy is very difficult to digest. Because the food industry spun soy as a health food, many people make soy products the base of their diets (soy protein, soy milk, soy snacks, tofu, etc) and in such doses it can absolutely cause problems. The point is to educate people about how to use soy products wisely.
Science is not based on anecdotes, it is based on research. It was disappointing to read nutrition consultant Mary Vance’s article, “Soy: To Eat or Not to Eat,” in the September 2013 issue. She reported a personal experience with soyfoods that resulted in adverse symptoms, which could have been due to sensitivities to soy, and used interviews and not research to support her thesis. The educated and health oriented readers of Experience Life Magazine should expect a reporter to reference peer-reviewed journals published in the past decade and seek a balance from those who have enjoyed and benefited from a food or diet as well as those who might have health reasons to avoid it. Ms. Vance’s story appeared to be based more on opinion than on facts. The following provides recent research that further elucidates some statements about soy in this article.
Allergies are something to take seriously and, if one is allergic to soy, it may cause bloating or digestive problems as Vance points out. Soy allergies, however, are extremely rare and are usually only found in children. According to the American College of Allergy, Asthma & Immunology, allergies to soyfoods affect less than 1% of children and most grow out of them by age 10, whereas the more prevalent allergies report milk (32%), followed by peanuts (29%), eggs (18%) and tree nuts (6%). In general, plant fibers are hard to digest and can cause bloating and indigestion when taken in large amounts.
Several of the experts cited on the ExperienceLife.com website are proponents of soy, including Dr. Andrew Weil, M.D., who says, “I still recommend one to two servings a day of whole soy foods. A serving is a cup of soymilk or one half-cup of tofu, tempeh, edamame or soy nuts. At those amounts you’ll get the benefits of soy without the theoretical risks of taking in too many isoflavones.”
Soybeans, just like most plants, contain phytoestrogens, such as isoflavones, that look similar in chemical structure to estrogens, but they behave differently in the human body. A serving of flax seed has nearly four times the amount of phytoestrogens as soybeans – and when it comes to soymilk, there is less than 10% of that found in flax. One slice of multi-grain bread has more phytoestrogens than soymilk. (Here is a chart comparing phytoestrogen content of foods.) And, although the idea of having phytoestrogens in soy formula might sound scary, the bio-activity of these phytoestrogens is 1/1000th that of estrogen, which is actually found in cow’s milk formulas. The total daily intake of isoflavones of an infant on soy formula is comparable to an adult consuming a modest amount of soy protein.
The effect of soy formula compared to breast milk and dairy formula on infant growth and development is actually being tested in a long-term study of 600 children at the Arkansas Children’s Nutrition Center. To date, the study shows soy-formula-fed infants developed at similar rates as breast-fed infants. In careful ultrasonic examinations of infants’ reproductive organs, the study did not find any estrogenic effects in the soy-formula-fed infants during the first four months of life, when development of reproductive organs is rapid. In fact, what it did find was evidence that ovarian development in girls may be faster in dairy milk-formula-fed infants and there were more ovarian cysts per ovary in milk-formula-fed than breast-fed babies.
Ms. Vance tries to link soyfoods with inadequate thyroid function in healthy people. Like all dietary fiber and some medications, goitrogens like soy isoflavone may take up some of the iodine the body would normally use to make thyroid hormone. For people with a healthy thyroid, the research shows positive or neutral effects of soyfoods. For those on thyroid medication, they may have to consult their doctors about adjustments. The Cancer Prevention Institute of California’s Bay Area Thyroid Cancer Study, for example, found that those who consumed the most phytoestrogens from soyfoods, whole grains, nuts and seeds had a markedly lower risk of thyroid cancer. Women who consumed the most soy had about half the risk of thyroid cancer compared to those who consumed the least.
Ed Bauman, Ph.D., is quoted in the Vance article, saying soybeans are not bad and “eating foods in their most pure and unadulterated state is a good thing.” We agree that no adulterated food should be consumed, but all plant foods have some anti-nutrients such as phytates and should be cooked, steamed, roasted, or fermented to reduce or eliminate them.
Ms. Vance is a little misleading in her categorization of soyfood processing. In short, soymilk is made from heating the soybeans and then pressing out the milk from the fiber without adding chemicals. Soymilk is then thickened to make tofu. Edamame can be eaten from the shell either boiled or baked, and soy nuts are just roasted soybeans. If one wants to avoid solvents, look for products marked “organic.”
The author also mentions the FDA announced in 2006 it was going to look at soy’s heart-health claim to lower cholesterol. The FDA at the time announced a plan to review several earlier health claims, but the claim still holds true and was not retracted. In fact, since 2006, multiple research studies have confirmed that soy protein in the diet lowers blood cholesterol from 5-10%. A 2007 review by a well-known cardiologist confirmed the cholesterol-lowering effect of soy protein. In a recent clinical trial, women with metabolic syndrome who ate soyfoods were able to decrease their LDL cholesterol levels by 5-10%.
Health advice from the Food and Drug Administration, the Dietary Guidelines for Americans, and the American Cancer Society has concluded: soyfoods are low in saturated fat, are high in complete protein, fiber and iron, contain essential omega-3 fatty acids, and are safe to eat.
Nancy Chapman, RD, MPH
Soyfoods Association of America
I am a father of a vegetarian 4 year old and my vegetarian wife is 3 months pregnant. I’ve been reading the The Whole Soy Story (hard for a layperson to fully digest, but I’m getting through it).
Currently, all three (including the fetus) eat soy all the time. I want to cut back, but I need ideas for a protein substitute for both of them. My 4 year old, well, she’s 4, so she’s picky. My wife is not as bad, but tempeh is not her thing.
I also want to echo Tara’s comments. My 4 year old went on soy formula after about 13 months, and the plan (before reading the book) was to do the same with the new baby. So any suggestions there would be helpful as well.
Please help!
Hi Mary, what a great article. However, as a first-time parent of a 14 month old with a milk protein allergy, I feel lost, not wanting to give him soy formula any longer. He has weaned himself from breastfeeding over the last few weeks and I’m unsure of what I should offer him now. Could you offer any guidance or suggestions?
Thank you!
coconut milk! it’s nutritious and tasty.
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