Broccoli inhibits cancer - mostly.

Estrogen is a major risk factor in breast cancer. Studies have shown that indole-3-carbinol (I3C), a component of many brassica vegetables (such as cabbage and broccoli), alters the way the body metabolizes estrogen -- stimulating the preferential production of a benign byproduct instead of a highly estrogenic and potentially carcinogenic one (SN: 7/3/93, p.10). In animal studies, this compound has even suppressed the natural rate of mammary tumor development.

But in acidic environments, such as the stomach, I3C will break down into a compound known as ICZ. And in cultured human breast cancer cells, ICZ exhibits both weak estrogenic and more strongly antiestrogenic activity, note Hong Liu of Texas A&M University in College Station and his coworkers in the Dec. 7 JOURNAL OF THE NATIONAL CANCER INSTITUTE.

ICZ's antiestrogenic activity probably contributes to its anticancer effects, the researchers say. Moreover, they argue, "publications that suggest that environmental estrogens may contribute to the increased incidence of breast cancer in women and disorders of the reproductive tract in men [SN: 1/22/94, p.56! have failed to take into account the existence and possible counteractive effects of both dietary and environmental antiestrogens" -- such as the ICZ they studied.