Genistein, an isoflavone derivative related to coumarin, is found in soy products and holds great promise as a natural cancer preventative. There are a number of isoflavones in soy products, but research has shown that genistein is the most potent inhibitor of the growth and spread of cancerous cells. Coupled with epidemiological studies, which suggest a strong cancer preventative effect of high soy diets, genistein is being scrutinized as a potential anti-cancer drug.

In Asia, soybeans (Glycine max) have been cultivated as a food crop for over five thousand years. Although the origins of the plant are obscure, many botanists believe it to have derived from Glycine ussuriensis, a legume family member native to central China. Today, soy plants are cultivated around the world with the United States being one of the leading producers. While soy still serves as a valuable source of protein for millions of people in Asia, over 90 percent of the soy crop grown in the United States is used to feed livestock.

Isoflavones are multipurpose biochemicals that have several functions in the soy plant: they contribute color to the soybean, protect the plant against bacterial and fungal infections, and serve a hormone-like role (as a phytoestrogen) in plant cell regulation.

Scientists are discovering that when people eat soy products, such as tofu and soymilk, isoflavones and their derivatives produce health benefits in addition to nutritional values. Research suggests that soy isoflavones benefit humans in four ways: as estrogens and antiestrogens, as cancer-enzyme inhibitors, as antioxidants, and as immune system enhancers or stimulants.