Influence of intestinal inflammation (IBD) and small and large bowel length on fecal short-chain fatty acids and lactate

Treatment with short-chain fatty acids (SCFAs) seems promising in ulcerative colitis and changes in colonocyte oxidation of butyrate have been suggested to be of importance for the development of this disease. The influence of small and large bowel length after surgery on SCFAs is only partly known. SCFAs and lactate were measured in consecutive fecal samples from 300 patients with ulcerative colitis (103), Crohn's disease (127), and noninflammatory bowel disease (70); 205 had had surgery, 52 had short bowels (<200 cm). Lactate (mainly thel-isomer) was elevated in ulcerative colitis patients with pancolitis (mean ±sem, 17±5 mmol/liter) and proctitis (12±3 mmol/liter) compared with quiescent ulcerative colitis (3±1 mmol/liter,P<0.01), and correlated with the index of Truelove (R=0.52,P<0.0005). Lactate was also increased in Crohn's colitis (21±8 mmol/liter), but not in isolated ileitis (4±2 mmol/liter), compared with quiescent Crohn's disease (7±2 mmol/liter,P<0.02), but did not correlate with the activity index (CDAI;R=0.18,P=0.12). In contrast to earlier reports, SCFAs (including butyrate) did not correlate with inflammatory activity or localization in either ulcerative colitis or Crohn's disease. The length of the small bowel had no influence on SCFAs and lactate in patients with either no colonic function (ileostomies), or with >50% and <50% preserved colorectal length, respectively. Fecal SCFAs from completely (100%) preserved large bowels (89±5 mmol/liter), and from>50% (76±7 mmol/liter) and<50% (72±7 mmol/liter) preserved colons were not significantly different, in contrast to SCFAs from ileorectals (51±10 mmol/liter), ileal reservoirs (57±6 mmol/liter), and ileostomies (20±2 mmol/liter). Fecal lactate is associated with proctocolitis, but not with ileitis. SCFAs were remarkably constant and not influenced by active inflammation in patients with inflammatory bowel disease or extreme differences in the length of the small or large intestine.