Soy is a wonderful vegetable source of complete protein that's low in saturated fats and cholesterol and rich in healthy fats, lecithin, fiber, calcium, magnesium, copper and B vitamins. However, the claims that have been made about soy being uniquely healthy as a food and supplement have become less certain as new research emerges. Claims that soy protein and its isoflavones contain unique properties that, when consumed in appropriate dosages, carry the promise of lowering cholesterol, improving bone health, diminishing symptoms of menopause, decreasing risks of breast and prostate cancer, slowing the cognitive declines of aging and degenerative brain diseases, reducing the risk of diabetes and enhancing weight loss have all fallen short of their goals. Calling soy protein and soy isoflavones "health foods" is now a very controversial topic among nutrition scientists and health agencies. You should continue to include soy in your diet and think of it as one of the other healthy foods you eat, but there is little support for — and some data against — the use of soy supplements. Susan Kleiner, PhD, RD, is an international columnist and a speaker on the subjects of nutrition, sports and fitness.