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Colonic bile acid exposure influenced IBS symptoms, therapy
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Patients with irritable bowel syndrome, primarily those who were nonconstipated, had elevated levels of colonic bile acid that was indicative of abnormal 75Se-labeled homocholic acid-taurine retention and high 7 alpha-hydroxy-4-cholesten-3-one serum levels in a recent study.
Swedish researchers enrolled 141 patients (mean age, 35.3 years; 72.3% women) with irritable bowel syndrome (IBS), who were subclassified as IBS-diarrhea predominant (IBS-D; n=65), IBS-constipation predominant (IBS-C; n=26) and alternating IBS (IBS-A; n=50). They measured patients for 75Se-labeled homocholic acid-taurine (75SeHCAT) retention, serum levels of 7 alpha-hydroxy-4-cholesten-3-one (C4) and fibroblast growth factor (FGF19).
The IBS cohort had lower 75SeHCAT retention values (28 ± 19% vs. 39 ± 18%; P=.005) at 7 days than 29 healthy controls without GI symptoms, and IBS patients displayed greater levels of C4c than controls (n=435) when adjusted for cholesterol (P<.001). FGF19 was considered similar.
Eighteen percent of IBS patients demonstrated abnormal 75SeHCAT retention (<10%), and 30 of 133 evaluable patients had high C4c values. Those with abnormal 75SeHCAT retention had more frequent stools (2.9 vs. 2.1 stools/daily; P=.01), greater BMI (26 vs. 23.1 kg/m2; P=.002), accelerated colonic transmit time (0.9 vs. 1.9 days; P=.007), rectal hyposensitivity (48.7 vs. 38.9 mm Hg; P=.008) and C4c values (11.5 vs. 3.7 mg/mol; P=.02), and lower FGF19 levels (99.2 vs. 149.7 pg/mL; P=.002) than IBS patients with 75SeHCAT retention greater than 10%.
IBS patients (n=27) treated with colestipol for up to 8 weeks showed improved IBS Severity Severity Scoring System grades (P<.01), including 15 patients who met treatment response criteria of at least 50% adequate relief of weeks 5 through 8.
“Our findings … strengthen the involvement of increased bile acid exposure in the colon as a partial mechanism for symptom generation in patients with especially nonconstipated IBS, that is, IBS-D and IBS-A,” the researchers concluded. “The positive symptomatic response to open label treatment with bile acid binders in patients with IBS with low 75SeHCAT values supports a role of bile acids in IBS symptomatology, but placebo-controlled studies are warranted.”
Disclosure: See the study for a full list of relevant financial disclosures.
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