The Dark Side of Soy

By Mary Vance, Terrain. Posted July 5, 2007.

This article from Terrain magazine was first reprinted by the Utne Reader in its July/August 2007 issue -- thanks to Utne for resurfacing it.

As someone who is conscious of her health, I spent 13 years cultivating a vegetarian diet. I took time to plan and balance meals that included products such as soy milk, soy yogurt, tofu, and Chick'n patties. I pored over labels looking for words I couldn't pronounce -- occasionally one or two would pop up. Soy protein isolate? Great! They've isolated the protein from the soybean to make it more concentrated. Hydrolyzed soy protein? I never successfully rationalized that one, but I wasn't too worried. After all, in 1999 the Food and Drug Administration (FDA) approved labeling I found on nearly every soy product I purchased: "Diets low in saturated fat and cholesterol that include 25 grams of soy protein a day may reduce the risk of heart disease." Soy ingredients weren't only safe -- they were beneficial.

After years of consuming various forms of soy nearly every day, I felt reasonably fit, but somewhere along the line I'd stopped menstruating. I couldn't figure out why my stomach became 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, heart protector and miracle food.

When I began studying holistic health and nutrition, I kept running across risks associated with eating soy. Endocrine disruption? Check. Digestive problems? Check. I researched soy's deleterious effects on thyroid, fertility, hormones, sex drive, digestion, and even its potential to contribute to certain cancers. For every study that proved a connection between soy and reduced disease risk another cropped up to challenge the claims. What was going on?

"Studies showing the dark side of soy date back 100 years," says clinical nutritionist Kaayla Daniel, author of The Whole Soy Story (New Trends, 2005). "The 1999 FDA-approved health claim pleased big business, despite massive evidence showing risks associated with soy, and against the protest of the FDA's own top scientists. Soy is a $4 billion [U.S.] industry that's taken these health claims to the bank." Besides promoting heart health, the industry says, soy can alleviate symptoms associated with menopause, reduce the risk of certain cancers, and lower levels of LDL, the "bad" cholesterol.

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 many of these studies credit a traditional diet that includes soy. But Asian diets include small amounts -- about nine grams a day -- of primarily fermented soy products, such as miso, natto, and tempeh, and some tofu. Fermenting soy creates health-promoting probiotics, the good bacteria our bodies need to maintain digestive and overall wellness. By contrast, in the United States, processed soy food snacks or shakes can contain over 20 grams of nonfermented soy protein in one serving.

"There is important information on the cancer-protective values of soy," says clinical nutritionist Ed Bauman, head of Bauman Clinic in Sebastopol, California, and director of Bauman College. Bauman cautions against painting the bean with a broad brush. "As with any food, it can have benefits in one system and detriments in another. [An individual who is sensitive to it] may have an adverse response to soy. And not all soy is alike," he adds, referring to processing methods and quality.

"Soy is not a food that is native to North America or Europe, and you have issues when you move food from one part of the world to another," Bauman says. "We fare better when we eat according to our ethnicity. Soy is a viable food, but we need to look at how it's used."

Once considered a small-scale poverty food, soy exploded onto the American market. Studies -- some funded by the industry -- promoted soy's ability to lower disease risk while absolving guilt associated with eating meat. "The soy industry has come a long way from when hippies were boiling up the beans," says Daniel.

These days the industry has discovered ways to use every part of the bean for profit. Soy 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 animal feed to muscle-building protein powders. "Soy protein isolate was invented for use in cardboard," Daniel says. "It hasn't actually been approved as a food ingredient."

Soy is everywhere in our food supply, as the star in cereals and health-promoting foods and hidden in processed foods. Even if you read every label and avoid cardboard boxes, you are likely to find soy in your supplements and vitamins (look out for vitamin E derived from soy oil), in foods such as canned tuna, soups, sauces, breads, meats (injected under poultry skin), and chocolate, and in pet food and body-care products. It hides in tofu dogs under aliases such as textured vegetable protein, hydrolyzed vegetable protein, and lecithin -- which is troubling, since the processing required to hydrolyze soy protein into vegetable protein produces excitotoxins such as glutamate (think MSG) and aspartate (a component of aspartame), which cause brain-cell death.

See more stories tagged with: soy

Mary Vance is the associate editor of Terrain.

Reprinted from Terrain (Spring 2007), published by Berkeley's Ecology Center. Dedicated to fine feature writing about environmental issues, Terrain is distributed free throughout Northern California. Subscriptions: $15/yr. (3 issues) from 2530 San Pablo Ave., Berkeley, CA 94702.

Liked this story? Get top stories in your inbox each week from Health and Wellness! Sign up now »