HTR5A and irritable bowel syndrome: Another experimental study showed that SCFAs regulate the synthesis and release of 5-hydroxytryptamine (5-HT), which plays an important role in the pathophysiological process of IBS, by acting on enterochromaffin cells, and that a decrease in SCFAs leads to abnormal levels of 5-HT, which in turn triggers the symptoms of IBS (Mars et al., 2020).