A latest research shows that gut flora can affect your mood and stress level. In fact, the digestive tract and the central nervous system maintain a complex two-way line of communication via the “gut-brain axis.” Studies where researchers manipulated the gut bacteria in mice have shown that these microbes influence how the brain develops, particularly the regions that influence the stress response and conditions related to stress, such as anxiety and depression. In addition, serotonin, the “happy hormone” has the highest concentration in the gut.  Hence, it is important to nurture your intestinal good bacteria to boost your mood.