What is the primary mechanism for the absorption of fructose?

The primary mechanism for the absorption of fructose in the intestines is facilitated diffusion. This process allows fructose to move across the intestinal cell membranes without the requirement of energy, which is an essential characteristic of facilitated diffusion. Specifically, fructose utilizes transporter proteins, such as GLUT5, which assist its movement down its concentration gradient into intestinal cells from the lumen of the intestine.

Fructose does not require active transport since it is not being moved against its concentration gradient, and it is also not involved in co-transport or endocytosis. Co-transport typically involves the simultaneous movement of one molecule along with another molecule that is moving down its concentration gradient, while endocytosis refers to the process where cells engulf substances, which is not applicable in the case of fructose absorption. Thus, facilitated diffusion is the accurate and primary mechanism through which fructose is absorbed in the digestive system.