Reduction of cancer risk by consumption of selenium-enriched plants: enrichment of broccoli with selenium increases the anticarcinogenic properties of broccoli.

Plant-based diets and phytochemicals present in plants are associated with decreased risk of cancer. Brassica species, and broccoli in particular, are associated with reduced risk of several important cancers. Selenium (Se) is an essential nutrient that is covalently bound in a number of different chemical forms found in plants. Broccoli accumulates Se many-fold beyond the concentration of Se in the soil, and the chemical form of Se in broccoli is similar to the chemical form in high-Se garlic, a food with unique chemoprotective properties. Se from broccoli grown to accumulate more than 500 micro g Se/g did not accumulate in rat tissues or increase glutathione peroxidase enzyme activity to the same extent as Se salts or seleno-amino acids. Se from high-Se broccoli decreased the incidence of aberrant crypts in rats with chemically induced colon cancer by more than 50%, compared with controls. Se from high-Se broccoli also decreased the incidence of mammary tumors in rats treated with 7,12-dimethylbenz(a)anthracene (DMBA) and tumor number and volume in APC(min) mice. These results suggest that development of methods to increase the natural accumulation of Se in broccoli may greatly enhance its health-promoting properties.