Organic acid levels in acidic, normal range, and alkaline feces. Feces from healthy volunteers were used as a baseline comparison control. Fecal samples were tested for organic acid levels, including detection of total organic acid, acetic acid, lactic acid, succinic acid, propionic acid, butyric acid, and formic acid. The data are plotted as mean ± SEM μmol/g of feces. *P < 0.05; **P < 0.01; and ***P < 0.001 by the Tukey multiple comparison test.