Soy

Soy products like tempeh, tofu and edamame can be an integral part of an optimal diet, and they are included in the USDA dietary guidelines in the protein, dairy and vegetable categories.

Soy’s and Women’s Health

Soy foods figure prominently in women’s health.  Soy is the #1 source of isoflavones and may provide protection against ovarian cancer, multiple myeloma and breast cancer. And breast cancer survivors who eat soy foods may have a much lower likelihood of cancer recurrence; in fact, one study showed regular consumption of just one cup of soy milk daily lowered overall mortality among breast cancer patients by up to 38%.

When it comes to endometrial cancer, menopausal women taking estrogen-containing drugs may experience an increased risk of endometrial cancer of as much as ten-fold, while phytoestrogen-containing foods like soy seem to be protective against endometrial cancer. In one study, women who ate the most soy had 30% less endometrial cancer and appeared to cut their ovarian cancer risk nearly in half. 

In addition, menopausal adult women who increase their phytoestrogen intake by eating soy foods may help reduce hot flashes; young girls who consume soy may help delay the onset of premature menarche and puberty. Soy foods, it should be noted, do not reduce male fertility.

Soy and bone health

Soy may prevent or improve osteoarthritis symptoms. Soy phytoestrogens seem to significantly boost bone mineral density. Genistein, the soy phytoestrogen, may prevent bone loss and accelerate new bone formation. Soy food consumption is also associated with lower bone fracture risk.

Additional Health Benefits of Soy

If improved bone health and reproductive health benefits aren’t enough, research suggests soy may reduce skin wrinkles, fight depression, lower cholesterol (though not as much as other beans), reduce allergy risk, prevent and improve asthma symptoms, protect against COPD and suppress storage of abdominal fat.

Like cow’s milk, soy milk may interfere with the beneficial effects of tea drinking on endothelial function.

Soy milk provides the same amount of calcium, and twice the antioxidant content, as cow’s milk. Nevertheless, consuming too much soy may negate some of the benefits of avoiding animal protein. Dr. Greger recommends no more than three to five servings daily.  

Soy is one of the most commonly grown crops in America, and most of it is used to make cheap animal feed. Most of the soy grown is GMO, but so far, there is limited data suggesting eating GMO soy is harmful to human health. Still, research on human placental tissue suggests pesticides on GMO soy may have toxic effects, and GMO soybeans are known to have more pesticide residues than conventional and organic soybeans. 

Image Credit: margouillatphotos / Thinkstock. This image has been modified.

Topic summary contributed by Randy