The versatile soybean, a common allergen, is in everything from soup to nuts. Is that good for us?
What do many breads, snack foods, canned tuna and margarine have in common? The answer is soy. A cheap source of protein and oil, food manufacturers put this legume in more than 60 percent of processed foods.
Soy can be found in baked goods, cereal, crackers, canned soups, vegetable broth, salad dressings, imitation bacon bits, energy bars, reduced-fat peanut butter, pasta, Worcestershire sauce, deli and luncheon meats and vegetarian meat alternatives. It’s also in some vitamin E supplements, prescription drugs and cosmetics. And don’t forget soy infant formula, soy milk, soy lattes, soy nut butter and soy veggie burgers. Americans love the soybean. Nearly one quarter of us report that we drink soy milk regularly.
This widespread prevalence makes avoidance challenging for those who are allergic to soy, one of the top eight food allergies in the United States. But how healthy is soy for the general public, even those who are not allergic to it?
Once a health-food darling credited with preventing breast cancer, lowering cholesterol and promoting strong bones, a different side of soy is now emerging. A rising chorus of critics say that soy may not be so good for us after all. While answers to the burgeoning debate remain unclear, two things are certain: Soy is one of the most common food allergies in U.S. children and the soy foods industry is booming.
Farmers in more than 30 states grow soybeans, making soy the United States’ second largest crop in cash sales and the No. 1 value crop export. In 2009, the total crop value exceeded $31.7 billion, according to the American Soybean Association.
In the ’70s and ’80s, soy was highly touted as a health food. As the legume’s popularity increased, so did the research into its health benefits. Researchers observed that Asian populations that consume a lot of soy have fewer cases of breast cancer, prostate cancer, cardiovascular disease, bone fractures and menopausal symptoms, like hot flashes, than Western populations.
Over the past two decades, studies in medical journals backed up these observations, asserting that soy supports cardiovascular health and bone health and that soy isoflavones (estrogen-like compounds) protect against breast cancer and prostate cancer.
In 1999, the U.S. Food and Drug Administration approved a health claim that “25 grams of soy protein a day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease.” This announcement was more good news for the soy foods industry. From 1992 to 2008, the sale of soy foods in the United States skyrocketed—from $300 million to $4 billion.
The Dark Side
But lately, another aspect of soy is emerging.
“There are a whole lot of problems associated with soy—thyroid disorders, digestive disorders, reproductive disorders,” says nutritionist Kaayla Daniel, PhD, author of The Whole Soy Story: The Dark Side of America’s Favorite Health Food. Also problematic is the fact that 91 percent of American-grown soy has been genetically modified (GMO) to tolerate herbicide, she says. The long-term effects of ingesting GMO foods has yet to be established.
At the center of the soy debate are soy isoflavones, phytoestrogens or plant compounds that have estrogen-like structures. Daniel and other critics say soy isoflavones are close enough to human estrogens to fool the body and cause early puberty in girls, promote breast cancer in women, reduce male fertility, cause thyroid dysfunction and delay or arrest the sexual maturation of boys.
“Obviously, anyone allergic to soy needs to avoid it completely,” Daniel says. “Others who may want to avoid soy as much as possible are people with thyroid and fertility problems, as well as women who have been diagnosed with or have a family history of breast cancer.”
Mark Messina, PhD, an expert who consults for the soy industry, disagrees and cautions people to look closely at the strengths and weaknesses of individual studies. Although some animal studies raise concerns about harmful effects of isoflavones, human studies support the safety and potential benefits of soy foods, he says. Yes, isoflavones do have a structure similar to human estrogens but they act differently in the human body. “Soy isoflavones can, in theory, have an estrogenic effect in some tissues and anti-estrogenic effects in others,” he says.
Indeed, there are many studies making opposing statements about soy, with well-funded activists on both sides. For the average consumer, the debate is dizzying.
To add to the confusion, some medical organizations have recently changed their recommendations about soy consumption. In 2000, the American Heart Association’s Nutrition Committee stated, “It is prudent to recommend including soy protein foods in a diet low in saturated fat and cholesterol.” In 2006, the AHA retracted its position, saying, “The direct cardiovascular health benefit of soy protein or isoflavone supplements is minimal at best.”
In 1998, the American Academy of Pediatrics said, “Isolated soy protein-based formulas are safe and effective alternatives to provide appropriate nutrition for normal growth and development.” But in 2008, the association recommended soy formulas in only two situations: “There are few indications for their use in place of cow milk-based formula. These indications include (a) for infants with galactosemia and hereditary lactase deficiency (rare) and (b) in situations in which a vegetarian diet is preferred.”
The American Cancer Society’s 2006 guidelines recommend that women with breast cancer should eat only moderate amounts of soy foods and should not take soy supplements, stating, “High doses of soy could possibly increase the risk of estrogen-responsive cancers, such as breast or endometrial cancer.”
A Traditional Tale
A 2009 study in the Journal of the American Medical Association looked at 5,000 Chinese breast cancer survivors and found that women who ate higher amounts of soy had an improved prognosis. Patients who consumed more than 15 grams of soy protein per day were about 30 percent less likely to suffer a recurrence and to die from their disease compared to women who ate less than 5 grams of soy protein per day.
But most of the women in the Chinese study ate traditional, whole soy foods, not genetically modified (GMO), processed soy protein or highly concentrated isoflavone supplements, which are often used in the United States.
In Asia, soy is primarily consumed in miso soup, tempeh and natto, foods in which the soy is fermented, a process that neutralizes the toxins in soybeans and creates health-promoting probiotics, Daniel says. Unfermented soy products have a high phytate content, which can block the absorption of minerals, especially calcium, zinc and magnesium.
Also, soy is traditionally eaten in small quantities as a condiment, not in large quantities as a meat replacement or a primary protein source, which is often the case for American vegetarians. A 1998 study of Japanese men and women showed the average consumption of soy protein in Japan at 7 to 8 grams per day, with isoflavone consumption at 25 milligrams.
Americans can easily consume more than that, primarily because of the way soy is packaged and sold here. Three daily servings of soy milk contain about 21 grams of soy protein and 75 milligrams of soy isoflavones. Some commercial soy shakes and soy bars are highly concentrated to contain 20 grams of soy protein and 160 milligrams of isoflavones in a single serving.
Allergy in Children
Soy allergy is one of most common food allergies in children in the United States. Experts once believed that most kids outgrew the allergy by age 3. However, a recent Johns Hopkins Children’s Center study shows the allergy is more persistent than once thought: 45 percent of children outgrow it by age 6 and 69 percent by age 10. Sensitivity usually starts in infancy, when many children are introduced to soy in infant formulas.
“Soy is a common allergy in infants because soy formula is frequently used as a substitute for milk,” says Anna Nowak-Wegrzyn, MD, associate professor of pediatrics at Mount Sinai School of Medicine in New York City.
In infants, the allergy commonly manifests with gastrointestinal symptoms, such as vomiting, diarrhea and poor weight gain. Soy is also a common culprit in infants and children who have chronic eczema. The allergy can show up in older youngsters as immediate IGE-mediated symptoms—hives, vomiting and/or anaphylaxis.
Soy formula is a good option for infants who are allergic to milk, says Nowak-Wegrzyn, because soy is better tasting, better accepted by infants and cheaper than hypoallergenic formula. However, 10 to 14 percent of milk-allergic infants with eczema or immediate symptoms, such as hives, will also have a soy-protein allergy. In case of gastrointestinal milk allergy in infants under 1 year of age, up to 50 percent may also react to soy.
Because infants go through developmental stages that are sensitive to estrogens, they’re more likely than adults to be vulnerable to the estrogen-like effects of the phytoestrogens in soy, according to the National Institute of Environmental Health Sciences.
The National Toxicology Program of NIEHS concludes that there is only “minimal concern for adverse effects on development in infants who consume soy infant formula” but does note that human studies have been limited and “the data in humans are not sufficient to dismiss the possibility of subtle or long-term adverse health effects in these infants.”
Dietitian Marion Groetch of the Jaffe Food Allergy Institute at Mount Sinai School of Medicine in New York City says that, for older kids, soy milk is a good alternative for those who are allergic to cow’s milk and are no longer taking a hypoallergenic formula.
“Soy is a nutritionally dense food providing protein, thiamine, riboflavin, pyridoxine, folic acid, calcium, phosphorus, magnesium, iron and zinc,” Groetch says. Enriched soy milk has a higher nutritional value than rice milk and it’s comparable to cow’s milk in terms of protein content and fat content, she says.
“There is currently an abundance of literature that points to the positive health effects of soy in the diet,” Groetch says. “In regards to safety in infancy and early childhood, soy has been used in this country for many decades and it appears to be safe through puberty—but long-term studies are needed.”
Many children who are allergic to soy have multiple food allergies. Since soy and peanuts are related—both are legumes—about 10 to 15 percent of people with peanut allergy also have soy allergy. However, peanut-allergic kids should not automatically avoid soy since most can tolerate it, Nowak-Wegrzyn says.
Not so for Cindy Smith’s 8-year-old daughter, Laney, who is extremely allergic to peanuts. At first, Laney ate soy products without a problem, says Smith, who lives in Highland Park, Illinois, and is a member of MOCHA, Mothers of Children Having Allergies. But when Laney was 5, the family went to their favorite Japanese restaurant and ordered the same meal Laney had eaten before: edamame and rice with soy sauce. This time, the little girl’s reaction to soy was different.
“When we left the restaurant, Laney began gasping, ‘I can’t breathe, I can’t breathe.’ She was turning blue,” says Smith, who quickly stuck her daughter with an EpiPen to halt the anaphylaxis and gave her Benadryl. “Our allergist later confirmed that Laney’s allergy to soy was very serious, calling it ‘a ticking time bomb.’”
The undiagnosed soy allergy was all the more dangerous because Laney’s severe peanut allergy and asthma had already compromised her lungs. A 1998 Swedish study noted four asthmatic youngsters who died from soy anaphylaxis. Like Laney, these kids were severely allergic to peanuts but had no previously known allergy to soy.
Smith resolved that her family would not eat any soy-containing foods for a year, even though her doctor said that soy lecithin, an emulsifier, and soy oil weren’t likely to present a problem.
“Every item in our pantry—snacks, crackers, cookies—had either soy oil or soy lecithin. I was in tears. I literally cleaned out the pantry,” Smith says.
Under U.S. labeling laws, any packaged food product that contains soy as an ingredient must list “soy” on its label. However, highly refined oils, including soy oil, are exempt since almost all the allergenic protein is eliminated in the processing. Most soy-allergic people can tolerate soy oil and soy lecithin—but each individual is different.
“Soy is a very, very tough ingredient to avoid,” says Roxanne Dominis, whose 3-year-old son, David, is allergic to soy and certain other foods. “It is in so many things, including personal care products, like bubble bath and shampoo, where it’s often labeled as tocopherol. You’ll even find soy in some processed hamburgers. Why would anyone put soy in hamburger?”
“The scariest place to go is a restaurant,” says Dominis, who lives in Forest Park, Illinois. “It’s challenging to figure out if a dish is safe and that ingredients don’t contain soy or aren’t cross contaminated. I ask the waitstaff whether a menu item is frozen or fresh. If it’s frozen, I ask to see the package. If they can’t produce the package, I don’t order that dish.”
To manage allergy-free meals while working as a social worker, Dominis plans far in advance. “We map out an entire month’s lunch and dinner menus, so we’re rotating foods and planning ahead. It’s so much less stressful day to day and it allows us to try new recipes on the weekends when we’re not as rushed.”
Dominis also consulted with an integrative nutritionist who helped teach the family how to eat healthy foods that avoided David’s allergies to nuts, legumes, soy, corn, dairy, gluten, eggs and nightshade vegetables. “She told us about alternative grains and roots that are safe for David. We also learned a lot about soy,” says Dominis, who is concerned about GMO soy, as well as the legume’s effect on hormones. “Before David’s diagnosis, soy milk was our family’s drink of choice. Now we don’t even have it in the house.”
As the debate about soy continues, what’s the health-conscious consumer to do?
Daniel, who wrote the book about soy’s “dark side,” notes that, for children up to age 18, the Israeli Health Ministry recommends consuming soy food or soy milk no more than once a day and no more than three times a week. “That’s the maximum I’d recommend for anyone for all types of soy foods,” she says.
Even Daniel eats soy in its traditional fermented forms. “I enjoy old-fashioned fermented soy products, such as miso, tempeh and natto, and eat them a couple times a week,” she says. “These are nourishing foods in the context of a richly varied diet.”
The bottom-line advice from many nutritional experts is this: If you’re consuming soy as part of a balanced diet, choose non-GMO soy and avoid highly processed forms, including soy isoflavone supplements, soy bars, soy shakes and, some say, soy meat substitutes. Instead, choose traditional fermented soy or one of the least processed forms of soybean limiting intake to no more than one serving a day, or three to five servings per week.
When it comes to consuming soy, the old adage “everything in moderation” holds true.
Writer Eve Becker lives in Chicago.