Correlation between indicators of intestinal environment and amount of carbon dioxide in gas excreted during defecation.

Intestinal microbiota have marked metabolic activity and influences the host in both beneficial and harmful ways. In the present study, we developed an apparatus to measure the amount of CO 2 in the gas excreted during defecation and investigated whether this amount of CO 2 can be used as an indicator of the intestinal environment. The apparatus consists of a fan and a commercial CO 2 sensor attached to a toilet stool. Fecal pH, fecal water content, concentrations of short chain organic acids (SCFAs) and intestinal putrefactive products and composition of fecal microbiota were analyzed as indicators of the intestinal environment. The apparatus could measure the amount of CO 2 in the gas with good reproducibility, irrespective of the open area at the top of the toilet stool, position of gas injection and composition of the gas. In a volunteer study, the amount of C0 2 in defecation gas correlated with pH, water content and concentrations of SCFAs and intestinal putrefactive products in the feces, although correlation with the composition of intestinal microbiota was not be observed. The results indicate that the amount of CO 2 in defecation gas can be measured with simple and sanitary procedures and is a good indicator of the intestinal environment.