Narrator: This is Science Today. There's yet another reason why you should be eating your vegetables, especially if you are a man. Nutritional scientist Leonard Bjeldanes of the University of California, Berkeley, has identified that a chemical called DIM - produced when digesting greens such as broccoli and kale - can stifle the growth of human prostate cancer cells.

Bjeldanes: DIM is the first example of a naturally occurring anti-androgen from plants that we know of. So this is quite remarkable.

Narrator: Early stage prostate cancer is responsive to the male hormone androgen and is typically treated with anti-androgen drugs. This makes the finding of an anti-androgenic chemical in Brassica plants, such as cabbage and bok choy, a promising find.

Bjeldanes: When we treated our tumor cells with the DIM again, it very strongly and very potently blocks the expression of that protein in these tumor cells. And what we think is going on is that you eat these plants over a period time and your tendency to develop cancer is less.

Narrator: For Science Today, I'm Larissa Branin.