Though the cause of IBS-D is still unknown, research suggests that multiple factors — such as the gut-brain axis, abnormal muscular contractions, gut microbes, hormones and genetics — could play a role in the disease.
IBS is twice as common in women compared to men, which could be explained, in part, by hormonal changes during the menstrual cycle.[1] Other evidence suggests that some women with IBS-D carry a gene mutation that affects their gut-derived serotonin receptors, which could lead to abnormal motility.[2][3]