Probiotics and depression

In patients with irritable bowel syndrome, the intake of probiotics promises to improve mood.

Advertisements of various probiotics for health benefits, both for gastrointestinal problems and issues that do not seem to be directly related to the intestine, are now very common. But do probiotics really work? A new study published in the journal Gastroenterology has shown that a specific probiotic can help treat depressive symptoms in patients with a very common gastrointestinal disorder, irritable bowel syndrome, or spastic colitis (IBS).

IBS is one of the most common bowel disorders, affecting approximately 10% of the world's population, and IBS patients often suffer from psychiatric symptoms such as depression and anxiety. Little is known about what causes irritable bowel syndrome and the accompanying psychiatric symptoms, but it seems that the bacteria in the gut, commonly known as the "gut microbiome," play an important role.

A new study by researchers at McMaster University (Canada) shows a link between taking probiotics and improving mood in patients with IBS and adds new evidence that gut bacteria may actually communicate with the brain to influence mood and behavior (brain-gut axis). In this study participated 44 patients with IBS, also suffered from mild to moderate depression and anxiety. Half of them received daily doses of the probiotic Bifidobacterium longum (B. longum), while the other half received a placebo for six weeks. Each individual completed questionnaires to measure depression and anxiety as well as gastrointestinal symptoms. At six weeks, the 64% of patients who received the B. longum probiotic showed an improvement in depression scores, compared with the 32% of those who received a placebo. The depression score remained lower in the B. longum group, even four weeks after the probiotic was stopped. However, it should be noted that neither the anxiety symptoms nor any of the gastrointestinal symptoms changed with this particular probiotic treatment.

Using functional magnetic resonance imaging or functional MRI (fMRI) to measure brain activation, the researchers found that improved depression in patients receiving B. longum was associated with changes in brain activity, especially in areas related to mood regulation. Showing patients specific images, they found that those taking the probiotic had a reduced response to stressful stimuli.

More studies are definitely needed to confirm these findings before this probiotic is used systematically as a medical treatment for IBS-related depression. However, patients receiving B. longum reported improvements in their overall well-being and quality of life, and the results of this study show that the probiotic B. longum has some antidepressant effects.

This opens up new avenues not only for the treatment of patients with functional bowel disorders but also potentially for patients with primary psychiatric disorders, such as clinical depression.