Short-chain fatty acids, lactate, and ammonia in ileorectal and ileal pouch contents: a model of cecal fermentation.

Fecal concentrations of total short-chain fatty acids were normal in 16 patients with ileorectal anastomoses (mean ± SEM, 99.7 ± 10.3 mmol/L) and 28 patients with ileal pouch-anal anastomoses (138.8 ± 8.5 mmol/L) and did not differ from those in 14 healthy noncolectomized controls (130.7 ± 12.6 mmol/L). Acetate:propionate:butyrate:isobutyrate+ valerate+isovalerate ratios were similar in the ileorectum (71:12:12:5%) and in the colorectum (66:14:13:7%) of healthy noncolectomized controls, whereas the concentration of acetate was increased at the expense of the polypeptide-derived isobutyrate, valerate, and isovalerate in the ileal pouch (77:12:11:1%). Ammonia was accordingly significantly diminished in ileal pouch contents (28.8 ± 3.2 mmol/L us 45.2 ± 4.1 mmol/L in controls) in contrast to concentrations in ileorectal contents (36.2 ± 5.3 mmol/L). Concentrations of lactate were normal and low. Twenty-four-hour productions of total short-chain fatty acids in 16.6% fecal homogenates from both groups of patien...