How Probiotics May Help Depression

Probiotics relieve depression

It is common for people with neurological disorders to suffer digestive disorders and vice versa. Many people who suffer from irritable bowel syndrome (IBS) also struggle with depression.


Now a study published in the journal Gastroenterology suggests that taking a probiotic supplement may provide relief from both conditions.


The randomized, placebo-controlled study found a connection between probiotics and mood improvement in people with IBS and depression or anxiety. The research also identified changes in the brain related to emotional processing in people taking the probiotic. Most previous research has focused on healthy people without mood disorders.


Canadian scientists recruited 44 individuals with IBS and mild-moderate anxiety or depression and followed them for 10 weeks.


Half took a daily dose of the probiotic Bifidobacterium longum and the other half took a placebo.


After six weeks, twice as many people taking the probiotic had lower depression scores compared to those taking the placebo.



The researchers used functional MRI scans to study the brain function of the study participants. They found that improved depression scores were associated with changed activity in several brain regions involved in mood regulation.


The data didn’t show significant independent changes in anxiety, constipation, diarrhea or pain (probably due to the small sample size), but people taking the probiotic did report improvements in overall symptoms of IBS and in quality of life.


One potential explanation for the improvement in mood in the probiotic group could be that because their physical symptoms feel better, their mood gets better too. In this respect, the fMRI findings are the most interesting and important aspect of the new study because they show that the probiotics may really be working on the brain itself.


Interestingly, the researchers found no significant changes in inflammatory markers between the probiotic and the placebo group. Therefore, the effects aren't due to systemic inflammation, which many experts believe is the main way gut bacteria influence the brain.


The study was a pilot trial, so the number of participants involved was relatively small. A much bigger trial will be required to confirm the results.