The role for bile acids in causation of irritable bowel gets a closer look in a recent publication (Clin Gastroenterol Hepatol 2012; 10: 1009-15).
This study randomly selected 52 participants (26 with diarrhea-predominant IBS, 26 with constipation predominant IBS) from a cohort of 700 IBS patients followed at the Mayo clinic along with 26 healthy volunteers. The ages of the patients ranged from 29-51. Subsequently, these patients underwent additional testing following a 4-day high fat diet. Of note, 5 of the IBS-D patients had a history of cholecystectomy compared with one patient in the other two groups.
In these patients, bile acid concentrations were measured in the stool and serum levels of 7α-hydroxy-4-cholesten-3-one (C4).In the IBS-D patients, serum levels of C4 were significantly higher than in the other two groups. 38% of the IBS-D group had elevated C4 levels; these elevated levels correlated with increased stool concentrations of bile acids.
The authors note that bile acid malabsorption has been identified frequently in patients with unexplained chronic diarrhea and that these patients often respond to bile acid sequestration (eg. cholestyramine or colesevelam). Another interesting finding was that obesity was associated with elevated bile acid levels. Overall, the cohort with IBS-D had an average BMI of 29.5.
So, what conclusions can be drawn?
- Serum C4 levels may be using in identifying patients with bile acid malabsorption
- Bile acid sequestration agents may be worth a try in some cases of IBS-D and this study provides a rationale
-Alim Pharmacol Ther 2009; 30: 707-17. Bile acid malabsorption in IBS-D.