Soy is good food, well worth adding to your diet – as soybeans, tofu, soy flour, or soy milk. Soy protein may help lower cholesterol and have anti-cancer effects. Food containing moderate-to-high levels of soy protein can now sport an official health label: if you eat 25 grams of soy protein in the context of a low-fat, low-cholesterol diet, it can help lower the risk of heart disease. But while it’s a good food, it’s not a magic bullet. Like all plants, soybeans are a mixture of complex substances with many potential effects in the body – some beneficial, some not.
(Source: UC Berkeley Wellness Letter: Healthy Eating)