Soy products like tempeh, tofu, and edamame are an affordable part of an optimal diet, and are included in the USDA dietary guidelines. Soy provides protein and magnesium (see also here), and arginine (which may stimulate fat-burning). This may help explain why soy may suppress fat storage, preventing increases in abdominal fat.
Soy is the #1 source of isoflavones and may provide protection against ovarian cancer, multiple myeloma, and breast cancer – starting in childhood (see also here) as well as prolonging breast cancer survival (see also here, here, here and here). Soy food intake also helps inhibit the enzyme TOR, which may increase cancer risk.
Soy products appear to help lower cholesterol (though not as much as other beans), which is why a soy-based Atkins diet does not have the same adverse impact. Soy ”bacon” does not appear to emit carcinogens when cooked, unlike regular bacon. Soy protein may be better for our kidneys than animal protein, and contains low amounts of the amino acid methionine, which may improve our lifespan.
Soy consumption may also be good for lung health as it may reduce allergy risk, prevent and improve asthma symptoms, and protect against COPD. Soy may also prevent and improve osteoarthritis symptoms, protect against skin wrinkles, and has been associated with lower risk of depression.
Phytoestrogen intake through soy consumption in menopausal adult women may help to reduce hot flashes, while for young girls it may help delay the onset of premature menarche and puberty. Contrary to internet memes, soy foods do not reduce male fertility.
Soymilk, like cow’s milk, may interfere with the benefits of tea such as chai. But as long as it’s shaken, it can provide the same amount of calcium as cow’s milk. Soymilk also has twice the antioxidant content than that of cow’s milk.
To maintain the low IGF-1 levels associated with a plant-based diet, one should probably eat no more than 3-5 servings of soy foods a day, as high IGF-1 levels have been associated with increased cancer risk.
Soy is one of the largest crops in America, and has been subsidized 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. Research on human placental tissue, though, does suggest pesticides on GMO soy may have toxic effects, and GMO soybeans are known to have more pesticide residues than conventional and organic soybeans.
Topic summary contributed by Randy.