FFAR2

Activators and inhibitors

FFAR2 and FFR3 are activated primarily by short-chain fatty acids (SCFAs) that are 2 to 6 carbons in length (see length of fatty acids). In humans, acetic acid, which has 2 carbon atoms, is a strong activator of FFAR2 but very weak activator of FFAR3; propionic and butyric acids, which have 3 and 4 carbons, respectively, are strong activators of both FFAR2 and FFAR3; pentanoic acid, which has 5 carbon atoms, is a weak activator of FFAR2 but strong activator of FFAR3; and hexanoic acid, which has 6 carbon atoms, is a weak activator of FFAR3 but its effect on FFAR2 has not been reported. More recently, the ketone body fatty acid, acetoacetic acid, while not classified as a SCFA, has been shown to activate FFAR2 with a potency similar to acetic and propionic acids.