Major depression is the second leading cause of disability worldwide, and is a significant contributor to suicide and heart disease. Therefore it is imperative that we strive to find new ways to prevent and manage depression. Recent advances in medical technology have allowed scientists to discover that our gut bacteria, something that little was known about in the past, is in fact a vital organ which not only helps to maintain the gut barrier, but also functions as a metabolic and endocrine organ. It appears our gut microbiome helps regulate immune function, cholesterol/lipid metabolism and even has an impact on our mental health. Early evidence that gut microbiota can influence serotonin and its precursor tryptophan highlights the microbiome as a potential target in the management and prevention of mental illness.
So the big question is, is it possible to manipulate the function of our microbiome to promote good mental health? Recent pre-clinical evidence suggests this may be possible. The composition of our microbiome is largely determined in our first few years of our life, but it appears that environmental factors such as stress, diet, medication, geography can change our microbiome’s function during adulthood. It is hypothesised that these changes are moderated by the central nervous system via the ‘gut-brain axis’. There is a large volume of observational data suggesting that healthier diets are significantly associated with lower rates of depression, across all ages and cultures. We also know that fat, protein and carbohydrate can alter the composition of gut microbiota. Pre-clinical studies have shown that antibiotics and prebiotics (which alter gut flora) are associated with a significant change in depressive behaviours. Could the improvement in depression observed when following a healthy diet be mediated by changes in the gut microbiome?
There is only one preliminary study which looks at the changes in gut microbiota in depression, and it had inconclusive results. Although research is in its early stages, this is an exciting new space to watch! Interestingly there are a few case studies of patients who have undergone faecal transplants to treat intestinal disease, whose depression has resolved following transplant…..food for thought.