Soy: Superfood or Health Hype?
Two new studies strengthen the claim that soy products can help prevent osteoporosis. Both studies found that consuming soy isoflavones (either in foods or supplements) reduced bone loss and increased bone density. These studies were both meta-analyses, which analyze the pooled data from several individual studies, and this theoretically gives these results greater weight. (Click here for more on the studies.)
Preventing osteoporosis is just one of many health benefits attributed to soy, although some of the others are controversial. The FDA (which is pretty stingy about such things) has approved the health claim that "Diets low in saturated fat and cholesterol that include 25 grams of soy protein a day may reduce the risk of heart disease." This statment has been challenged by some who feel that an aggressive soy lobby pushed the FDA to approve the claim despite "immature" evidence.
As a trip down supplement aisle of your local health food store will demonstrate, soy is also touted as a natural remedy for menopausal symptoms and other problems associated with "hormone imbalance." The idea here is that the weak plant estrogens in soy are similar enough to human estrogen that they are able to plug into the estrogen receptors on human cells. There, they supposedly supply a small dose of estrogen (which helps relieve symptoms caused by low estrogen levels)--and there is research to back this up.
At the same time, soy estrogens are believed to block stronger estrogens from plugging into the receptors, thereby reducing the risk of hormone-driven cancers. But this is also an area of controversy. It is true that Japanese women, who eat more soy, have lower rates of breast cancer (and hot flashes) than Western women. But it has not been definitively proven that these lower cancer rates are due to soy consumption. In fact, there is some concern that over-consumption of soy products could be dangerous for women with or at risk of estrogen-sensitive cancers. (Unfortunately, we never seem to be able to do anything in moderation!)
And to muddy the waters just a bit more, soy isoflavones can interfere with thyroid function in susceptible individuals and the naturally-ocurring phytates in soy can inhibit the absorption of calcium, magnesium and other minerals.
Despite all the questions that remain about safety and efficacy, soy is still widely regarded (and promoted) as a health food. Brace yourself for "Soyfoods Month" a PR extravaganza sponsored every April by the Soy Food's Association of North America.
Personally, I think that soy foods are fine in moderation.They are a high quality, inexpensive vegetarian source of protein, and can be delicious. I'm a big fan of edamame (steamed soybeans in the pod) and I love miso soup. But, as with anything, it's possible to overdo it. People get the idea that soy is healthy and before you know it, they're eating soy milk over soy nuggets for breakfast, soy burgers with soy cheese on soy bread for lunch, soy chili and frozen soy yogurt for dinner every day.
Let's use some common sense: For most people, a serving or two of soy protein a day is not going to create thyroid problems or mineral deficiencies and--as part of a varied, balanced diet--may have some health benefits. I suggest that you discuss the use of any soy isoflavone supplements with your doctor or nutritionist.
I no longer eat soy, having seen articles stating that it is now genetically modified.