PYY and multiple sclerosis: For example, propionic acid stimulates the release of peptide YY and glucagon-like peptide-1 in human colonic cells, and thereby reduces energy intake and weight gain.51 Intriguingly, propionic acid stimulates Muc2 production by IECs by regulating the expression of the prostaglandins.52 A recent study proposed that supplementation of propionic acid improves the Treg/Th17 imbalance in multiple sclerosis patients.53 Taken together with our results, we conclude that propionic acid may play an important role in IEC homeostasis and the overall gut, and therefore may modulate host physiology.