Selenium from high selenium broccoli protects rats from colon cancer

Colon cancer is the third most common newly diagnosed cancer in the United States and the third most common cause of cancer-related deaths. Previous s upplementation studies have demonstrated the efficacy of selenium (Se) for prevention of colon cancer in humans. The metabolism of Se depends on its c hemical form, and studies have shown that the chemical form of Se in brocco li does not accumulate in the body as fast as other forms of Se and may be especially beneficial for prevention of cancer. In the first experiment of the present study, Fisher F-344 rats (n = 45) were allotted randomly to tor ula yeast-based diets supplemented with the following: 1) no Se; 2) 0.1 mu g Se/g diet as selenate; 3) 1.0 mu g Se/g diet as selenate; 4) 0.1 mu g Se/ g diet as selenized broccoli (Se concentration of similar to 500 mu g/g); o r 5) 1.0 mu g Se/g diet as selenized broccoli. In Experiment 2, rats (n = 8 0) were allotted randomly to the same basal diet supplemented with the foll owing: I) no added Se; 2) 2.0 mu g Se/g diet as selenite; 3) 2.0 mu g Se/g diet as selenite + low Se broccoli; and 4) 2.0 mu g Se/g diet as selenized broccoli. Rats were fed the diets for 2 wk and injected with a chemical car cinogen (3,2 dimethyl 4-amino biphenyl or dimethyl-hydrazine in Experiment 1 or dimethyl hydrazine in Experiment 2; 2 rats/treatment were used as vehi cle controls). Supranutritional amounts of Se supplied as high Se broccoli significantly decreased (P < 0.05) the incidence of aberrant crypts (AC) an d aberrant crypt foci (ACF; preneoplastic lesions indicative of colon cance r) compared with other dietary treatments. Diets were controlled for the pr esence or absence of broccoli and for the total amount of Se. The reduction in AC and ACF was a function of Se in high Se broccoli and not a result of broccoli alone or Se alone. Adequate dietary Se supplied as high Se brocco li did not accumulate in tissues or increase glutathione peroxidase activit y as well as other forms and amounts of Se. Thus, Se from high Se broccoli may be metabolized in a manner that diverts much of the Se into a pool that provides protection against colon cancer.