Short-chain fatty acids in bowel contents after intestinal surgery

Short-chain fatty acids are produced in the human colon by bacterial fermentation of dietary fibers and other saccharides escaping absorption in the small bowel. Short-chain fatty acid concentrations were determined together with production rates in 6- and 24-h incubations of intestinal outputs from 56 patients with various types of intestinal resections. Concentrations and 6- and 24-h production rates in feces from 9 healthy persons (controls; median ± SD) were 98.9 ± 21.4 mmol/L and 17.2 ± 5.1 and 9.3 ± 1.5 mmol/L · h, respectively. Colectomized patients with short bowel syndrome had extremely low concentrations (0.8 mmol/L) compared with controls (p < 10-5), patients with ileostomy (p = 0.003), and ileal reservoirs (p < 10-5), and showed low 6- and 24-h production rates (1.5 and 0.9 mmol/L · h, respectively; p < 10-5 vs. controls). Short-chain fatty acids in ileostomic digesta (11.1 mmol/L) were decreased (p = 0.011) compared with outputs from ileal reservoirs (51.5 mmol/L), although production rates were in the same order of magnitude—all below control values (p < 0.001). Patients partially colectomized and patients with small bowel bypass or short bowel syndrome with preserved colon had normal fecal concentrations with decreased production rates of short-chain fatty acids vs. controls (p < 0.01). Only minor changes in ratios between individual acids were found. Reciprocal values of short-chain fatty acid concentrations correlated to volumes of outputs from both small intestine (r = 0.86, p < 10-6) and colon (r = 0.79, p < 10-6) when results were cumulated. It is concluded that partial resections of colon and the small bowel do not influence the fecal concentration level of short-chain fatty acids as long as colon is not totally resected.