The soybean has been prized for centuries in Asia as a nutritious, high-protein food with a myriad of uses, and today it's popular in the United States not only in Asian food, but also as a cholesterol-free meat and dairy substitute in traditional American foods. Soy burgers, soy yogurt, tofu hot dogs, and tofu cheese can be found in a growing number of grocery stores alongside the traditional white blocks of tofu, and soy is increasingly used as a protein filler in many prepared foods, including fast-food “hamburger.”

Soy appears to reduce blood cholesterol levels, and the US Food and Drug Administration has authorized allowing foods containing soy to carry a "heart-healthy" label.

Soybeans contain isoflavones, chemicals that are similar to estrogen. These are widely thought to be the active ingredients in soy, although, as discussed below, there is substantial evidence that other constituents may be equally or more important. Much of the information in this article overlaps with that in the Isoflavone article.

If you like Japanese, Chinese, Thai, or Vietnamese food, it's easy to get a healthy dose of soy. Tofu is one of the world's most versatile foods. It can be stir-fried, steamed, or added to soup. You can also mash a cake of tofu and use it in place of ricotta cheese in your lasagna. If you don't like tofu, there are many other soy products to try: plain soybeans, soy cheese, soy burgers, soy milk, or tempeh. Or, you can use a soy supplement instead.