Dietary fat and cecal microbial activity in the rat

Abstract

Weanling rats were fed low‐fat (1 % w/w safflower oil) or high‐fat (1% w/w saf‐flower oil plus 35% w/w beef fat or cocoa butter) diets for 30 days, and the activities of five cecal microbial enzymes were determined. When compared with the low‐fat diet, beef fat significantly increased total cecal β‐glucuronidase activity, but cocoa butter, with a similar fatty acid composition, did not. Both high‐fat diets significantly decreased total cecal azoreductase, β‐glucosidase, and nitrate reductase activities, but neither significantly affected urease activity. When expressed as specific activities (per 10¹¹ bacteria), cocoa butter decreased azoreductase, and beef fat caused increases of β‐glucuronidase and urease. Beef fat, but not cocoa butter, significantly reduced cecal bacterial numbers when compared to the low‐fat diet. Both high‐fat diets led to equivalent reductions in the proportion of aerobic bacteria.