Randomized clinical trial: effect of Lactobacillus plantarum 299 v on symptoms of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common diagnosis in gastroenterology. Its etiology is unknown and therapeutic options limited. Trials suggest probiotics may be beneficial. The aim of this study was to assess the symptomatic efficacy of Lactobacillus plantarum 299 v (L. plantarum 299 v) for the relief of abdominal pain in patients with IBS fulfilling Rome II criteria.

This study was conducted in a referral hospital. Trial participants were randomized to receive either two capsules of L. plantarum 299 v at a dosage of 5 × 10(9) cfu per capsule or placebo daily for 8 wk. Severity of abdominal pain was assessed using a visual analog scale at each visit and a quality-of-life IBS (QoL-IBS) questionnaire was also completed.

There was no significant difference in abdominal pain relief between the study and placebo groups (P = 0.800). There was also no difference in QoL- IBS scores between the groups (P = 0.687). Both groups had a significant improvement in abdominal pain scores over the study period, from an average of 251.55 to 197.90 (P < 0.0001) indicating a large placebo effect.

An 8-wk treatment with L. plantarum 299 v did not provide symptomatic relief, particularly of abdominal pain and bloating, in patients fulfilling the Rome II criteria.