Effect of the probiotic strain Bifidobacterium animalis subsp lactis, BB-12®, on defecation frequency in healthy subjects with low defecation frequency and abdominal discomfort: a randomised, double-blind, placebo-controlled, parallel-group trial

The aim of the present study was to investigate the effect of Bifidobacterium animalis subsp. lactis, BB-12 (R), on two primary end points defecation frequency and gastrointestinal (GI) well-being - in healthy adults with low defecation frequency and abdominal discomfort. A total of 1248 subjects were included in a randomised, double-blind, placebo-controlled trial. After a 2-week run-in period, subjects were randomised to 1 or 10 billion colony-forming units/d of the probiotic strain BB-12 (R) or a matching placebo capsule once daily for 4 weeks. Subjects completed a diary on bowel habits, relief of abdominal discomfort and symptoms. GI well-being, defined as global relief of abdominal discomfort, did not show significant differences. The OR for having a defecation frequency above baseline for >= 50 % of the time was 1.31 (95% CI 0.98, 1.75), P=0.071, for probiotic treatment overall. Tightening the criteria for being a responder to an increase of > 1 d/week for >= 50% of the time resulted in an OR of 1.5 (95% CI 1.22, 1.96), P=0.0003, for treatment overall. A treatment effect on average defecation frequency was found (P=0.0065), with the frequency being significantly higher compared with placebo at all weeks for probiotic treatment overall (all P<0.05). Effects on defecation frequency were similar for the two doses tested, suggesting that a ceiling effect was reached with the one billion dose. Overall, 4 weeks' supplementation with the probiotic strain BB-12 (R) resulted in a clinically relevant benefit on defecation frequency. The results suggest that consumption of BB-12 (R) improves the GI health of individuals whose symptoms are not sufficiently severe to consult a doctor (ISRCTN18128385).