INHIBITION BY WHEAT BRAN CEREALS OF THE DEVELOPMENT OF ABERRANT CRYPTFOCI AND COLON TUMORS

As variation in both type of fibre and its physical properties can inf luence physiological effects, the effects of different dietary levels (1, 4, 8%, w/w) of unprocessed wheat bran (WE) were compared with thos e of two of its processed commercial formulations used in breakfast ce reals, on the formation of aberrant crypt foci (ACF) and colon tumours in Fischer 344 rats following azoxymethane (AOM) administration. All diets were high in fat (20 g/100 g) and low in calcium (0.2%, w/w). Th e rats were fed the experimental diets for 2 wk before receiving two s c injections of AOM (15 mg/kg body weight/wk). 8 wk following the firs t injection of AOM, five rats per group were killed and the formation of ACF was measured. 23 wk following the first injection of AOM, 12 ra ts per group were killed and the colon tumour incidence in different d ietary groups was measured. The results showed that increasing the die tary concentration of fibre from 1 to 8% (w/w), using all the wheat br an formulations, significantly reduced the number of ACF per rat. None of the diets showed any significant effect on the normal growth of ra ts. No statistically significant differences were observed between the protective properties of WE and the two commercial formulations under investigation in terms of the reduction of the number of ACF, or in t erms of the reduction of the colon adenocarcinoma incidence. The resul ts suggest that wheat bran and its two commercial formulations can off er protection against colon cancer even when they are consumed with a high-fat/low-calcium diet. The addition of any of these formulations o f wheat bran fibre is likely to be equally effective in the prevention of colon cancer in human populations that habitually consume high-fat /low-fibre Western-style diets. (C) 1997 Elsevier Science Ltd.