Scientists: Soy health risks numerous
“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.
Soy also is one of the foods–in addition to wheat, corn, eggs, milk, nuts, and shellfish–most likely to cause allergic reactions. Most people equate food allergies with anaphylaxis, or a severe emergency immune response, but it is possible to have a subclinical sensitivity, which can lead to health problems over time (and is exacerbated by the lack of variety common in today’s American diet).
“People can do an empirical food sensitivity test by eliminating the food for a period of time and reintroducing it to see if there’s an immune response, but most don’t do this,” says Bauman. “Genetically modified (GM) soy is the most problematic, and that’s probably what most people are eating if they’re not paying attention. 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.”
Yet avoiding GM soy doesn’t mean all is well, Daniel says: “One question I get all the time is, ‘What if I only eat organic soy?’ The assumption is that GM soy is problematic and organic is fine. Certainly, organic is better, but the bottom line is that soybeans naturally contain plant estrogens, toxins, and antinutrients, and you can’t remove those.”
The highest risk is for infants who are fed soy 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 will affect the hormonal development of these children, and it will certainly affect 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. The Israeli health ministry recently issued an advisory stating that infants should avoid soy formula altogether.
Antinutrients in soy block enzymes needed for digestion, and naturally occur-ring phytates block absorption of essential minerals. This is most worrisome for vegans and vegetarians who eat soy as their main source of protein, and for women in menopause who up their soy intake through supplements.
Soy contains phytochemicals–plant nutrients with disease-fighting activity–called isoflavones. Studies claim isoflavones can mimic the body’s own estrogens, raising a woman’s estrogen levels, which fall after menopause, causing hot flashes and other symptoms. On the other hand, isoflavones 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. (High estrogen levels have been linked to cancers of the reproductive system in women.)
Although soy’s isoflavones may have an adaptogenic effect (contributing to an estrogen-boosting or -blocking effect where needed), they also have the potential to promote hormone-sensitive cancers in some people. Studies on the effects of isoflavones on human estrogen levels are conflicting, and it’s possible that they affect people differently. In men, soy has been shown to lower testosterone levels and sex drive, according to Daniel.
“There are a lot of problems with these studies,” Daniel says, adding that the 1999 heart health claim was an industry-funded initiative. “Even if there is positive information, and even if these studies are well designed, we need to weigh that against the fact that we’ve also got really good studies showing the dangers. Better safe than sorry is the precautionary principle. Possible bene-fits are far outweighed by proven risks.”
Daniel and Bauman agree on the benefits of variety. “My experience as a clinical nutritionist is that people who have a varied diet tend not to get into trouble,” says Daniel.
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