The feeling of nausea that comes when you hear unexpected news isn’t just a coincidence. The connection between your brain and your stomach is very tight, and is the reason we use phrases like “trust your gut,” or “what is your gut telling you?” Even though these sayings have been around for a long time, it’s very easy to overlook the connection between your stomach and your brain. Sometimes when you’re feeling low, you have to go back to the basics; in this case, the basics refer to what your body is telling you. New research is showing that the makeup of bacteria in your gut can also influence your emotional health. Gut microorganisms are capable of producing and delivering neuroactive substances such as serotonin and gamma-aminobutyric acid, which act on the gut-brain axis. Preclinical research in rodents suggested that certain probiotics have antidepressant and anxiolytic activities. Effects may be mediated via the immune system or neuroendocrine systems. Others have proposed that the gut microbiome may hold promise for fighting stress, anxiety. Interestingly, trials in post traumatic stress disorder patients (PTSD) are ongoing to evaluate the effect of orally administered Lactobacillus reuteri on the disease. The oral administration of L. reuteri via lozenges has been proposed to be useful to treat chronic periodontitis. In 2016 a team of researchers at the University of Colorado Boulder found that treating mice with beneficial bacteria helped them to become more resilient to the stress of residing with much larger, aggressive mice.