The gut-brain axis is the bidirectional communication highway between your gut and brain, operating via the vagus nerve, immune signals, and gut-produced neurotransmitters. Your gut produces over 90% of the body's serotonin and significant amounts of GABA, dopamine precursors, and other neuroactive compounds. This is why chronic stress causes IBS flares, why anxiety manifests as stomach pain, and why digestive diseases are so strongly associated with depression and anxiety disorders.
