Scientists identify 'sixth sense' in gut bacteria that signals brain to stop eating

Within the living ecosystem of the human gut, scientists at Duke University have discovered that ancient bacterial proteins are not silent passengers but active messengers, speaking directly to the brain through a network of specialized nerve cells and the vagus nerve. A protein called flagellin, found on the tails of common gut bacteria, triggers a fullness signal that travels upward to suppress appetite — a biological conversation that has been happening inside us long before we had words for hunger. Published in Nature, the research reframes digestion itself as something closer to a sensory