Even though the gut-brain connection is still being studied, there is strong evidence so far to support the fact that microbial communities can influence the brain and mental health states. The gut is known as the “second brain” because many types of neurons and nerves in the gut communicate directly with the brain. There is a direct and systemic connection between the gut and the brain through vagal and sympathetic nerves, neurotransmitters, cytokines, and other molecules. When it comes to mental health, gut microbial communities have been shown to play a role in many disease states. Depression, stress, anxiety, autism spectrum disorder have stood out to scientists thus far as studies have shown the connection between the mental health issue and the dysbiosis of the gut bacteria. In the majority of the studies mentioned, supplementation of a good strain of bacteria was able to alter the microbial communities present and decrease symptoms related to a mental disorder. These relationships are very interesting because they could provide new avenues for better understanding the complexity of mental disorders and ways they could be treated.