COMPARISON OF PURE INOSITOL HEXAPHOSPHATE AND HIGH-BRAN DIET IN THE PREVENTION OF DMBA-INDUCED RAT MAMMARY CARCINOGENESIS

Inositol hexaphosphate (IF,), abundant in cereals and legumes, has bee n demonstrated to be a promising anticancer agent in different in vivo and in vitro models. Because IP6 is particularly abundant in the bran part of certain mature seeds such as wheat, we investigated whether a high-fiber bran diet containing high IF, shows a dose-response inhibi tion of 7,12-dimethylbenz[a]anthracene (DMBA)-induced rat mammary carc inogenesis. Starting at two weeks before DMBA intubation, rats were di vided into five groups and fed AIN-76A diet only or AIN-76A diet conta ining 5%, 10%, or 20% Kelloggs' All Bran, the fifth group received 0.4 % IP6 given in drinking water an amount equivalent to the IP6 content in 20% bran. After carcinogen administration, the rats remained on the se regimens for 29 weeks. Compared with the carcinogen control, at 29t h week, tumor incidence was reduced by 16.7%, 14.6%, and 11.4% in rats fed 5%, 10%, and 20% bran, respectively (not statistically significan t). However, mts given 0.4% IP6 in drinking water equivalent to that i n 20% bran, had a 33.5% reduction in tumor incidence (p < 0.02) and 48 .8% fewer tumors (p < 0.03). These data show that supplemental dietary fiber in the form of bran exhibited a very modest, statistically nons ignificant inhibitory effect, which was also not dose dependent. In co ntrast, animals given IP6 showed significant reduction in tumor number , incidence, and multiplicity Thus IP6, an active substance responsibl e for cereal's beneficial anticancer effect, is clearly more effective than 20% bran in the diet. In practical terms, intake of IP6 may be a more pragmatic approach than gorging enormous quantities of fiber for cancer prophylaxis.