Wheat aleurone flour increases cecal beta-glucuronidase activity and butyrate concentration and reduces colon adenoma burden in azoxymethane-treated rats

Processed wheat aleurone flour (WAF) is a source of insoluble fermentable d ietary fiber that comes from the outer layers of the wheat kernel. A study was designed to evaluate WAF, wheat bran (WB) and alpha -cellulose as the s ource of dietary fiber (5 g/100 g of diet) in a semipurified high fat (20 g /100 g of as 1:1 lard/sunflower seed oil) diet fed to male Sprague-Dawley r ats in which intestinal tumors were induced using azoxymethane (AOM). WAF a t 33 g/100 g of diet (WAF33) and WB at 16 g/100 g of diet (WB16) increased the weight of feces and produced significantly higher concentrations in the cecum of the short-chain fatty acid butyrate (P < 0.001) than did no fiber (NF) and WAF added at only 10 g/100 g (1.5 g of dietary fiber) (WAF10). Ce cal and fecal pH were both significantly lower in the WAF33 and WB16 treatm ents relative to control and no fiber treatments (P < 0.001). The intestina l tumors in the rats were assessed at 6 mo after the study began, and the W AF33- or WB16-fed rats showed a trend (P = 0.06) with 43% fewer colon adeno mas relative to control. There was a significant inverse relationship betwe en beta -glucuronidase activity and colon adenomas in the rat colon (r(2) = 0.37, P = 0.001). WAF fiber influenced some metabolic markers of fermentat ion in the colon in a manner similar to that of WB, which, independent of t he bulking effect, was associated with a trend to reduced colon adenomas. S ignificantly increased cecal beta -glucuronidase activity and/or butyrate c oncentrations may have protective influences in this context by mechanisms not yet fully elucidated.