Although serotonin is well known as a brain neurotransmitter, it is estimated that 90 percent of the body’s serotonin is made in the digestive tract. In fact, altered levels of this peripheral serotonin have been linked to diseases such as irritable bowel syndrome, cardiovascular disease, and osteoporosis. New research at Caltech, published in the April 9 issue of the journal Cell, shows that certain bacteria in the gut are important for the production of peripheral serotonin.
