The nonfermentable dietary fiber lignin alters putative colon cancer risk factors but does not protect against DMH-induced colon cancer in rats

Abstract The effect of supplementation of the diet with auto‐hydrolyzed lignin on 1,2‐dimethylhydrazine (DMH)‐induced colon carcinogenesis was studied using 112 male Sprague‐Dawley rats. Rats received eight weekly injections of DMH (9.5 mg/kg sc) or the saline vehicle solution and then were maintained on a basal AIN‐76 fiber‐free diet or the basal fiber‐free diet plus 5% or 10% (wt/wt) lignin for 24 weeks. Rats were killed 32 weeks after the start of the experiment. Colon tumor incidence, location, and multiplicity were determined. Body weight, caloric intake, fecal dry weight, gut transit time, pH of cecal contents, and total fecal bile acid excretion were measured. Supplementation of the diet with 5% or 10% lignin resulted in increased fecal dry weight and total fecal bile acid excretion and in decreased gut transit time, colon pH, and fecal bile acid concentration. Dietary lignin did not significantly affect colon tumor incidence or multiplicity compared with the fiber‐free diet. Thus dietary supplemen...