Some probiotic bacteria are able to manufacture and secrete substances that can be used in the brain as neuromediators. A recent review compiled the results and found in favour of the concept of “psychobiotics”, i.e. the use of probiotic strains to combat psychiatric disorders or disease. For example, certain strains of Lactobacillus and Bifidobacterium produce gamma-aminobutyric acid (GABA), one of the chief inhibitory neurotransmitters. GABA-related anomalies are known to have an impact on anxiety and depression. In rats, the ingestion of Bifidobacterium infantis increased their serum levels of tryptophan, a precursor of serotonin which is highly involved in mood regulation.
A promising therapeutic strategy for depression
It has also been reported that other strains are able to produce adrenaline, serotonin and dopamine. Finally, a study on humans demonstrated the stress-reducing effects of taking a combination of probiotics for 30 days.
Based on the above, probiotics appear to offer a new and promising strategy for treating stress and depression.