The relationship between diet and rat fecal bacterial enzymes implicated in colon cancer

J Natl Cancer Inst. 1976 Aug;57(2):371-5. doi: 10.1093/jnci/57.2.371.


We studied the effect of diet on the activities of four enzymes found in the intestinal flora of the male F344 rat. Animals initially fed a diet with high vegetable and grain content were shifted to a diet consisting predominantly of beef. While eating the meat diet, the rats had significantly higher levels of nitroreductase, azoreductase, and beta-glucuronidase in their fecal flora when compared to levels measured during grain feeding. However, beta-glucosidase activity was significantly lower during meat feeding, which probably reflected the lack of beta-glucosidic linkages in this diet. These findings suggested that a high-beef diet, similar in composition to that consumed by humans with a relatively high risk of colon cancer, is associated with elevated levels of specific enzymes in the colon microflora. These enzymes have been implicated in the conversion of procarcinogens into carcinogens.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Azo Compounds
  • Bacteria / enzymology
  • Colonic Neoplasms / enzymology*
  • Colonic Neoplasms / etiology
  • Diet* / adverse effects
  • Feces / enzymology*
  • Feces / microbiology
  • Glucosidases / metabolism
  • Glucuronidase / metabolism
  • Intestines / microbiology
  • Male
  • Meat / adverse effects
  • NADH, NADPH Oxidoreductases
  • Neoplasms, Experimental / enzymology
  • Neoplasms, Experimental / etiology
  • Nitro Compounds
  • Nitroreductases
  • Oxidoreductases / metabolism
  • Rats
  • Rats, Inbred F344


  • Azo Compounds
  • Nitro Compounds
  • Oxidoreductases
  • NADH, NADPH Oxidoreductases
  • Nitroreductases
  • azoreductase
  • Glucosidases
  • Glucuronidase