The Gut Brain Axis and Anxiety & Depression
Psychobiotics affect psychophysiological markers of anxiety and depression.
"Understanding the correlation between the microbiome and mental health first takes an understanding of how the microbiome affects mood. There have been numerous research studies that suggest lack of gut biodiversity can affect neurotransmitter functionality and decrease signals via the vagus nerve.
One interesting study, by Vitetta et al. (2014), found that depression was accompanied by the activation of immune-inflammatory pathways. It was demonstrated that when mice with imbalanced gut flora were given a probiotic with Lactobacili, GABA in the brain was increased, which influenced signaling via the vagus nerve. This stabilized mood and behavior. Further, "anxious rats" that were treated with probiotics showed lower levels of anxiety, fear, and a decrease in stress hormones.
Tillisch et al. (2013), state that probiotics may improve symptoms of depression through anti-inflammatory actions, raising the possibility that this internal inflammatory response slows signaling via the gut-brain axis possibly creating neurotransmitter imbalance along the way."