Clinical trial for probiotics in irritable bowel syndrome fails to show efficacy

Irritable bowel syndrome is the most common functional gastrointestinal disorder, affecting about 10-15% of people in the United States alone, according to the International Foundation for Functional Gastrointestinal Disorders website. Fortunately, as described by the IFFGD, IBS is a functional disorder, meaning that while it does affect quality of life, it does not affect life expectancy. Probiotics have been studied as treatment for IBS because, as we’ve seen in many other examples of probiotic use, it is safe and rarely has any negative effects on the consumer. Some trials have shown that probiotics help relieve the symptoms of IBS; however the conclusions are controversial due to study structure and participant numbers. For this reason, scientists in Seoul, South Korea recently published a study in the Journal of Clinical Biochemistry and Nutrition, which studied the effects of a multi-species probiotic mixture on IBS symptoms using a double-blind study with a large number of participants.

Eighty-one patients participated in the 4-week-long double-blind study, with 42 people receiving a multi-species probiotic (containing Lactobacilli, Bifidobacteria, and Streptococci) and 38 people receiving a placebo. Baseline fecal samples were collected before probiotic/placebo consumption, revealing no significant difference between the two groups of participants. After consumption, the probiotic group showed a significant increase in concentrations of the probiotic bacterial strains in fecal samples, but not significant increase of levels of Bacteroidetes and Firmicutes.

In terms of symptom relief, while the probiotic group reported a greater percentage of relief, it was not significantly greater than the placebo group. This could be a classic case of the placebo effect, which is a phenomenon in which a sham treatment can actually improve symptoms because the person receiving the placebo believes it will help them. The results of this study are not concrete because there was no significant difference in symptom improvement; however there were significant increases in probiotic strains in fecal samples of the probiotic group. This study could be a step in the right direction toward relieving IBS symptoms.

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