What I've Learned About Long COVID: A Gut-First Framework — 10. The Gut-Brain Axis: How Your Gut Tells Your Brain It’s Broken

Your gut doesn&#8217;t exist in isolation. The vagus nerve, circulating metabolites, and bacterial-derived neurotransmitters create a two-way conversation with your central nervous system. Dysbiotic bacteria produce less GABA, less short-chain fatty acids, more inflammatory mediators. Your gut barrier dysfunction means more bacterial antigens and toxins crossing into the bloodstream, activating microglia in your brain. The neuroinflammation in long COVID isn&#8217;t primarily a virus in your brain&#8212;it&#8217;s a signal from a broken gut.