It began with researchers finding ‘neurons’ in the gastrointestinal or GI system, perhaps a million or more. Then the estimate was revised upwards to maybe 200-600 million. Hmm-m-m. Now it appears that there may be as many neurons in your gut as you have in your brain. These gut neurons look like those in the brain in hour head, eat the same neurotrophic food, and use many of the same neurotransmitters. Estimates are that 90-95% of all the serotonin in your entire body lives in your gut. The serotonin helps trigger digestion and collaborates with the immune system to protect you from undesirable microorganisms. Neurons also utilize serotonin to send signals up to the brain in your head, information that can impact your desire to eat or not to eat.