Scientists from McMaster University (Canada) have found that intestinal microflora affects anxiety and depression. They first investigated the role of microflora in behavioral change after suffering stress at an early age.
Scientists have conducted experiments on laboratory mice. They stress the young by taking them away from their mother for several hours. After that, the mice showed signs of anxiety and depression, and their levels of the stress hormone corticosterone increased. In addition, their intestines were disrupted. When the experiment was conducted on mice with sterile intestines (no bacteria), they also increased their stress hormone levels, but their behavior did not change. If the intestines of such animals were inoculated with microorganisms from anxious mice, then they also fell into depression. This indicates complex mechanisms of interaction between the intestinal microflora and the brain.
Studies have shown that the link between gut function on the one hand and emotional and cognitive processes on the other is mediated through bi-directional neuroendocrine regulation, immune activation and gut-to-brain signaling, and tryptophan metabolism. An increase in the synthesis of tryptophan, a precursor of the hormone “happiness” serotonin, leads to improved mood, decreased pain, and improved sleep.