Studies on the mechanism of cancer protection by wheat bran: effects on the absorption, metabolism and excretion of the food carcinogen 2-amino-3-methylimidazo [4,5-f]quinoline (IQ)

We examined ways in which dietary supplements of wheat bran may protect aga inst colon cancer. The effects of supplementing the diet of female Wistar r ats with 10% wheat bran on the disposition and metabolism of the dietary ca rcinogen 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) labelled with C-14 wa s determined. Our data show that the wheat bran had a major effect on both the distribution and metabolism of IQ, At a low dose of IQ (1 mg/kg), we un expectedly found that up to 2 h after gavage there were higher concentratio ns of radioactivity in the plasma of rats fed wheat bran compared with the controls, but there were lower concentrations of radioactivity after 2 h, A t a high dose of IQ (50 mg/kg), there were always lower concentrations of r adioactivity in the plasma of rats fed wheat bran compared with the control rats. One of the most marked effects of wheat bran was apparently to signi ficantly retard the metabolism of IQ in the plasma when this was fed at eit her dose. There were also differences between the rats fed wheat bran and t he control in the concentrations and types of IQ metabolites in the urine.