What does your gut microbiome actually do for your health?

Your gut microbiome is the community of trillions of bacteria, fungi, and other microbes living in your digestive tract. These microbes break down dietary fiber into short-chain fatty acids like butyrate, which fuel colon cells and reduce inflammation. They also synthesize certain vitamins, including B12 and K2, and help regulate how well you absorb nutrients. Beyond digestion, the microbiome plays a major role in immune function, since roughly 70 percent of your immune system is located in the gut. It communicates with the brain through the gut-brain axis, influencing mood and stress responses partly through serotonin production. A disrupted microbiome has been linked to conditions like obesity, type 2 diabetes, inflammatory bowel disease, and even depression.