Could Probiotics Improve Depression and Anxiety Symptoms in IBS Patients?

Probiotics may improve quality of life scores and alleviate depression symptoms in patients with irritable bowl syndrome (IBS), according to the findings of a recent study.

The randomized, double-blind, placebo-controlled study included 44 adult patients with IBS and mild to moderate anxiety and/or depression. Patients were evenly divided into groups that took either Bifidobacterium longum NCC3001 (BL) or placebo once a day for 6 weeks. At baseline, week 6, and week 10, researchers assessed levels of anxiety and depression, IBS symptoms, quality of life, and somatization of patients. In addition, urine and blood samples were collected at baseline and week 6, and functional magnetic resonance imaging (fMRI) tests were performed to assess brain activation patterns.
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Of the 22 patients who received BL, 14 patients experienced a reduction in depression scores of 2 points or more on the Hospital Anxiety and Depression scale by week 6 compared with 7 patients in the placebo group. Patients who received BL had a mean increase in quality of life scores compared with patients who received the placebo. In addition, fMRI analysis showed that BL reduced responses to negative emotional stimuli in multiple areas of the brain, including the amygdala and fronto-limbic regions.

However, BL did not show any significant effect on anxiety or IBS symptoms.

Fecal microbiota profiles, serum markers of inflammation, and levels of neurotrophins and neurotransmitters were similar between the two groups, but urine levels of methylamines and aromatic amino acids metabolites were lower in the BL group.

By week 10, patients who received BL had reduced depression scores compared with patients who received the placebo.

“In a placebo-controlled trial, we found that the probiotic BL reduces depression but not anxiety scores and increases quality of life in patients with IBS,” the researchers concluded. “These improvements were associated with changes in brain activation patterns that indicate that this probiotic reduces limbic reactivity.”

—Melissa Weiss


Pinto-Sanchez MI, Hall GB, Ghajar K, et al. Probiotic Bifidobacterium longum NCC3001 reduces depression scores and alters brain activity: a pilot study in patients with irritable bowel syndrome [published online May 5, 2017]. Gastroenterology.