Irritable bowel syndrome symptom severity improves equally with probiotic and placebo

World J Gastroenterol. 2016 Dec 28;22(48):10631-10642. doi: 10.3748/wjg.v22.i48.10631.


Aim: To determine the effects of Lactobacillus acidophilus 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 109 or 1010 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 (P value for placebo vs 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.

Keywords: Abdominal pain; Functional bowel disorder; Intervention; Irritable bowel syndrome; Lactobacillus acidophilus; Probiotic; Quality of life; Symptom questionnaire; Visceral pain.

Publication types

  • Clinical Trial, Phase II
  • Multicenter Study
  • Randomized Controlled Trial

MeSH terms

  • Abdominal Pain / drug therapy*
  • Adult
  • Colon / metabolism
  • Dose-Response Relationship, Drug
  • Female
  • Humans
  • Intestinal Mucosa / metabolism
  • Irritable Bowel Syndrome / drug therapy*
  • Lactobacillus acidophilus / chemistry*
  • Male
  • Middle Aged
  • Pain Measurement
  • Probiotics / administration & dosage
  • Probiotics / adverse effects
  • Probiotics / therapeutic use*
  • Receptors, Opioid / drug effects*
  • Severity of Illness Index
  • Surveys and Questionnaires
  • Treatment Outcome
  • Visceral Pain / drug therapy*


  • Receptors, Opioid