CONCENTRATIONS AND CORRELATIONS OF FECAL SHORT-CHAIN FATTY-ACIDS AND FECAL WATER-CONTENT IN MAN

Faecal concentrations of short chain fatty acids (SCFAs) and faecal wa ter content were determined in 93 healthy volunteers. We found positiv e correlation between faecal water content and the concentration of ac etic, propionic and butyric acid. Multiple correlations between differ ent SCFAs were found and grouping of the correlations according to an assumed substrate specificity was observed. Acetic, propionic and n-bu tyric acid, that are derived from carbohydrates, were best related to each other, whereas the minor acids, derived mostly from proteins, for med another group. Some specific features of the blanched chain fatty acids (iso-acids) were discovered: their faecal concentrations were ve ry strongly correlated to each other (Rho=0.977), they did not correla te with the total concentration of SCFAs, and showed negative correlat ions to the faecal water content. These findings suggest that the iso- acids have common and specific substrates in vivo, possibly of endogen ous origin.