A new area of research in live bacteria is the field of psychobiotics, looking at the specific effects of bacteria and the microbiome on mental health. There is a strong association between the gut and the brain and gut dysbiosis is linked to mood disorders and vice versa. Up to 90% of serotonin is produced in the gut and everyone is familiar with the feelings that we get in the gut in response to stress or anxiety. Human studies are in their infancy, but some studies do suggest that live bacteria, such as Lactobacillus acidophilus and Bifidobacterium bifidum can support mood.

This may also be due to the compounds, known as postbiotics that these bacteria produce and due to the fact that a diverse microbiome is also associated with lower inflammation, and inflammation can be a marker for depression.Link to Article