Since research is showing a significant amount of neurotransmitters are produced in our digestive tract, would it make sense that specific strains and/or improving digestive wellness could influence mood, sleep, and function of neurotransmitters?

The term “neurotransmitters” refers to neuroactive substances that include amino acids such as glutamate and  g-aminobutyric acid (GABA), as well as biogenic amines such as dopamine, serotonin, and histamine. Neurotransmitters are found in natural food sources and several gut bacteria are known sources of neurotransmitters, however, the function of bacterial-derived neurotransmitters is not clear. Evidence demonstrates that gut microbiota can influence serotonin production in gut tissue, and in addition, microbiota-brain communication influences neurotransmitters in the brain, although this is not a direct action of neurotransmitters produced by commensal bacteria.

The role of specific bacterial gut taxa in mood, sleep, and brain function is an active area of research. Several pathways of microbiota-brain communication are known including the immune system, endocrine connections such as the hypothalamic-pituitary-adrenal (HPA) axis, and neural pathways involving the enteric nervous system. Research has demonstrated the utility of several strains of probiotics that have been clinically shown to decrease overall cognitive reactivity to sad mood, rumination, negative thoughts, and aggressive thoughts. These specific strains have demonstrated influence on the gut-brain axis through mechanisms including strengthening of the gut barrier function, modulation of cytokines and inflammatory response, production of potentially neuroprotective metabolites, and HPA regulation.

References

Steenbergen L, Sellaro R, van Hemert S, Bosch JA, Colzato LS. A randomized, controlled trial to test the effect of multispecies probiotics on cognitive reactivity to sad mood. Brain Behav Immun. 2015 Aug;48:258-64

Abildgaard A, Elfving B, Hokland M, Wegener G, Lund S. Probiotic treatment reduces depressive-like behaviour in rats independently of diet. Psychoneuroendocrinology. 2017 May;79:40-48.

This question was answered by Jane Foster, PhD, and Leah Linder, ND.