Probiotics could relieve the symptoms of depression, according to research published in the journal Gastroenterology.
The study, at McMaster University in the US, found that when irritable bowel syndrome was treated with a specific probiotic (Bifidobacterium longum NCC3001) patients experienced fewer symptoms of depression.
The study involved 44 adults with IBS and ‘mild to moderate’ anxiety or depression. Over a period of 10 weeks, half took a daily dose of the probiotic and the other half took a placebo.
After six weeks, 14 out of 22 patients (or 64 per cent) of those taking the probiotic had decreased depression scores, compared to seven of 22 (or 32 per cent) of those taking the placebo.
These findings were backed up by functional magnetic resonance imaging (fMRI), which showed that the improved scores were associated with changes in multiple brain areas involved in mood control.
The study’s authors say this provides further evidence of the direct link between the gut’s microbiotic environment and the brain.
Dr Premysl Bercik, the study’s senior author, said: ‘This study shows that consumption of a specific probiotic can improve both gut symptoms and psychological issues in IBS. This opens new avenues not only for the treatment of patients with functional bowel disorders but also for patients with primary psychiatric diseases.
‘This is the result of a decade-long journey — from identifying the probiotic, testing it in preclinical models and investigating the pathways through which the signals from the gut reach the brain.’
This is a randomised controlled trial, which is the highest level of evidence when it comes to assessing treatment of disease, save for the pooling of the results of many such trials in a meta-analysis or systematic review.
It is, however, a pilot study, meaning a preliminary study done to assess the feasibility of performing a larger study of similar design. Smaller studies, no matter how well performed, can often indicate positive results that are not subsequently replicated in a larger study.
Depression is a major cause of morbidity and mortality among those it affects. Despite years of research and therapy, we still know very little about the root causes and hence treating it can be a profound challenge.
This study’s strength is that it points the way to further research into this debilitating condition. Should its promise be replicated in larger studies, we may have another tool in the armoury of treatment.
The effect of the gut biome (gut bacteria) on human health is something we have relatively little data on; research in this area has suggested that there is a profound body of knowledge yet to be ascertained and the potential is exciting in terms of possible therapies for a vast array of disease. We are exploring the tip of what appears to be a phenomenally large iceberg.
Hippocrates said: ‘All disease begins in the gut.’ Modern medicine has looked scornfully on this idea, but it looks like there is more truth to it than we thought and for vastly more profound reasons than simple biochemistry.
Research score: 3/5