As research into the microbiome expands, our understanding of the gut-brain connection deepens. Phrases like “gut feeling” or “butterflies in your stomach” reflect a real biological link: the gut is often referred to as our second brain.
“Studies show that 40 to 60 percent of your neurotransmitters—chemical messengers the nervous system uses to communicate—are produced in the gut,” says Dr. Lela Altman, N.D., who maintains a private practice in Seattle and oversees digestive wellness programs at the Bastyr Center for Natural Health.
“The important takeaway is that while we’ve long assumed stress in the brain drives gut problems, evidence increasingly suggests the reverse can be true: gut health can influence mental health. For people with anxiety and depression, improving gut health often leads to improvements in mood, and when mental health improves, overall health tends to follow.”
Recent findings clarify why this connection is so powerful: the gut generates 80 to 90 percent of the body’s serotonin, a neurotransmitter linked to mood regulation, and about half of its dopamine, which contributes to pleasure and reward. The condition of the gut and its microbial community is now known to affect not only mood, anxiety, and depression, but also inflammation, immune function, and the risk of chronic disease.