Serotonin is often described as the happiness chemical because of its well-known role in regulating mood. However, recent research suggests this familiar molecule may play an unexpected role in cancer development. Not through its effects on the brain, but through a completely different mechanism in other parts of the body. Despite serotonin being commonly associated with the brain, almost 95% of the body's serotonin is produced in the gut. From there, it enters the bloodstream and travels to