High fat diet elevates the activity of inducible nitric oxide synthase and 1,2-dimethylhydrazine-induced aberrant crypt foci in colon of rats.

Rats were examined for the effect of dietary level of fat (beef tallow or safflower oil) on colonic activity of inducible nitric oxide synthase (iNOS) which has been suggested to be associated with colon carcinogenesis. In experiment 1, feeding high fat diets (20%) for 3 weeks caused higher activity of the iNOS compared to feeding low fat diets (5%). In experiment 2, rats were fed 20% or 5% beef tallow diet for 11 or 32 days, and given an injection of a carcinogen, 1,2-dimethylhydrazine on day 4. The activity of colonic iNOS and the development of colonic aberrant crypt foci were enhanced by high fat diet.