APOA4 is a major protein component of chylomicrons in postprandial lymph and plasma. It is synthesized in the small intestine and the liver, attached to chylomicrons by enterocytes, and secreted into intestinal lymph during fat absorption. APOA4 is intimately involved in metabolism and has protective roles in cardiovascular diseases like atherosclerosis. APOA4 can promote INS secretion and maintain glucose homeostasis. It also has potent antioxidant and anti-inflammatory properties.