https://www.caltech.edu/news/microbes-help-produce-serotonin-gut-46495 https://www.caltech.edu/news/microbes-help-produce-serotonin... Although serotonin is we

https://www.caltech.edu/news/microbes-help-produce-serotonin-gut-46495 https://www.caltech.edu/news/microbes-help-produce-serotonin... 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.