The duodenum and upper jejunum absorb the bulk of the dietary sugars. However, different sugars have different mechanisms of absorption. For example, galactose and glucose are transported into the mucosal cells by an active, energy-requiring process that requires a concurrent uptake of sodium ions; the transport protein is the sodium-dependent glucose cotransporter 1 (SGLT-1). Fructose uptake requires a sodium-independent monosaccharide transporter (GLUT-5) for its absorption. All three monosaccharides are trans- ported from the intestinal mucosal cell into the portal circulation by yet another transporter, GLUT-2.