There is a second nervous system in your body, one so complex and autonomous that scientists call it "The Second Brain." It is located not in your skull, but in your gut. This represents the Enteric Nervous System (ENS). And it doesn't just digest food. It manufactures the chemistry of your mood.

While other microbes are busy fighting for sugar, L. brevis is quietly performing a chemical conversion that has profound implications for the human brain. It takes Glutamate—an excitatory molecule—and transforms it into GABA, the molecule of calm.