The effect of supplementation of the diet with autohydrolyzed
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 s.c.) 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 supplementation with autohydrolyzed
lignin, a food fiber with good bulking characteristics, had a significant effect on several factors that have previously been linked to reduction of
colon cancer risk, but the consumption of high levels of
lignin did not decrease the risk for
colon cancer.