Excretion of Creatine and Creatinine in Feces of Man 1

Abstract

Summary

To examine the effects of a high beef diet on the bacterial flora and chemical composition of feces, 10 healthy human adults were fed four diets in succession for 1 month each: a control diet, meatless diet, high beef diet, and a repeat control diet. As a part of the larger study, creatine and creatinine were measured in the food consumed and in the feces excreted. Food creatine concentration was 5- to 12 -fold greater than creatinine; food creatine and creatinine were increased 4- and 10-fold, respectively, in the high beef diet compared with the control diets. Fecal creatine concentration was significantly elevated during the high beef diet (1.3-fold) over that in the control diets, whereas fecal creatinine excretion was elevated with only the meatless diet. Thus, creatinine and creatinine are present in human feces, and dietary creatine has an incomplete absorption during consumption of high beef diets.