Irritable bowel syndrome symptom severity improves equally with probiotic and placebo. Lyra Anna,Hillilä Markku,Huttunen Teppo,Männikkö Sofia,Taalikka Mikko,Tennilä Julia,Tarpila Anneli,Lahtinen Sampo,Ouwehand Arthur C,Veijola Lea World journal of gastroenterology AIM:To determine the effects of NCFM on irritable bowel syndrome (IBS) symptoms and quality of life (QoL). METHODS:In this randomized triple-blind trial, adult IBS volunteers who were recruited according to Rome III criteria received 10 or 10 colony-forming units of NCFM or placebo daily for 12 wk. IBS Symptom Severity Score (IBS-SSS), which constituted the primary outcome, and secondary outcomes, including individual IBS symptoms, IBS-related QoL questionnaire, anxiety and depression, defecation frequency, and stool consistency, were assessed at baseline at the end of the 8-wk run-in period, after 4 and 12 wk of intervention, and after a 4-wk washout. RESULTS:A total of 340 of 391 randomized volunteers completed the trial. IBS-SSS improved over 12 wk of treatment in all treatment groups, decreasing by a mean ± SD of 44.0 ± 80.2, 50.8 ± 82.4, and 48.3 ± 72.2 in the placebo, active low-dose, and active high-dose groups, respectively. Similarly, secondary outcomes did not differ between treatment groups. However, in a post hoc analysis of volunteers with moderate to severe abdominal pain at baseline (VAS > 35/100), the treatment significantly reduced the sensation of abdominal pain. Pain scores fell by 20.8 ± 22.8, 29.4 ± 17.9, and 31.2 ± 21.9 in the placebo, active low-dose, and active high-dose groups, respectively ( value for placebo combined active doses = 0.0460). CONCLUSION:NCFM alleviates moderate to severe abdominal pain, consistent with earlier observations of this strain mitigating visceral pain through increased analgesic receptor expression. 10.3748/wjg.v22.i48.10631