Fructose is absorbed from the gastrointestinal (GI) track) by a different mechanism than glucose.
Fructose absorption uses facilitated diffusion, the rate of which may depend on the concentration of sugar.
Fructose must attach to a specific carrier to across the wall of the small intestine. The number of fructose carrier is limited; therefore if the amount of fructose in the small intestine is greater than the number of carrier present, then some of the fructose will not be absorbed.
A carrier known as GLUT 5 is necessary for fructose absorption.
Fructose is carried directly to the liver via portal vein, which will eventually be converted to glucose by liver cells.
The liver stores and releases glucose as needed to maintain constant blood glucose level.
Fructose also enters muscle and other cells without depending on insulin, whereas most glucose enters cell in an insulin-dependent manner.
Finally, one inside the cell, fructose, can enter the pathways that provide the triglyceride backbone (glycerol) more efficiently than glucose.
Fructose absorption
