Short-chain fatty acids and the irritable bowel syndrome: the effect of wheat bran.

Short-chain fatty acids (SCFA) in faeces were examined in 18 patients with the irritable bowel syndrome (IBS) during treatment with wheat bran or placebo. In the placebo period, the patients could be classified in accordance with the faecal concentrations of SCFA into one group with low concentrations (mean, 40 mmol/l; range, 19-77 mmol/l; 10 patients) and another with high concentrations (mean, 168 mmol/l; range, 145-187 mmol/l; 8 patients). The concentrations of SCFA differed (P less than 0.001) in both groups from concentrations found in faeces from a reference group of nine normal individuals (mean, 114 mmol/l; range, 93-155 mmol/l). Patients with low levels of SCFA had lower (P less than 0.001) mean stool mass and longer (P less than 0.05) transit times than those with high concentrations of SCFA in faeces. Ingestion of bran, although a precursor of SCFA, did not change faecal concentrations of SCFA. Abdominal pain, distension, and rumbling were not correlated to low or high concentrations of SCFA in faeces, nor did bran improve these symptoms when compared to placebo. The level of SCFA was rather constant intraindividually and independent of the variability of the daily faecal mass. It is concluded that patients with IBS apparently have continuously abnormal concentrations of SCFA in faeces, either high or low, which are unaffected by the treatment with bran and which hypothetically may be of pathophysiologic importance.

The effect of coarse wheat bran in the irritable bowel syndrome. A double-blind cross-over study.

Dietary supplementation with wheat bran has been widely advocated as a first-line treatment of patients with the irritable bowel syndrome (IBS). Few controlled trials have been reported, and the results are, furthermore, contradictory. The present study comprised 20 patients with IBS, of whom 18 (14 women, 4 men) completed the trial. The two treatment periods of 6 weeks each, with a daily intake of 30 g coarse wheat bran or 30 g placebo bran, respectively, were randomized in a double-blind cross-over design. Wheat bran significantly (P less than 0.05) increased the stool weight and shortened the intestinal transit time but was without significant effect on the colonic motility index was shown. We conclude that coarse wheat bran used as the only treatment in IBS does not provide a sufficient effect in a 6-week period. However, wheat bran seems to be justified in the treatment of constipation.

Effect of oat bran on lithogenic index of bile and bile acid metabolism.

Epidemiological studies lend support to the hypothesis that high-fibre diets might prevent and low-fibre diets might facilitate the formation of cholesterol gall stones. In the present study, the bile compositions after ingestion of oat bran 18 g/day and placebo 18 g/day for 2 X 2 weeks were compared in a randomized, double-blind cross-over study in 6 healthy volunteers. The lithogenic index of bile was not influenced, whereas the following changes (0.05 less than p less than 0.10) occurred: the cholic acid pool was enlarged, the relative proportion of chenodeoxycholate in bile was increased and that of deoxycholate reduced, while cholate remained unchanged. It is concluded that oat bran seems to influence the metabolism of bile acids.

Enzymatic determination of total 3 alpha-hydroxy bile acids in faeces. Validation in healthy subjects of a rapid method suitable for clinical routine purpose.

A method for determining faecal bile acids, suitable for clinical purposes, is introduced. The analysis uses a 0.2-g stool specimen, a simple extraction procedure, and 3 alpha-steroid dehydrogenase determination. The method, which is rapid, has been validated by gas-liquid chromatography and by recovery of internal standards. Stool examination was done in 16 healthy volunteers on free diet and in 25 patients with non-gastrointestinal diseases who were on a fat- and fibre-fixed diet. No difference was found between the two groups, so the data were pooled, and the normal reference interval (mean +/- S.D.) for faecal bile acid output was calculated to be 0-975 mumol/24h.