Through what mechanism are glucose and galactose absorbed in the intestines?

Glucose and galactose are absorbed in the intestines primarily through active transport via SGLT-1, which stands for Sodium-Glucose Cotransporter 1. This mechanism is crucial because it leverages the sodium gradient established by the sodium-potassium pump (Na+/K+ ATPase) present on the basolateral membrane of intestinal epithelial cells.

As sodium ions are transported out of the cell, a concentration gradient develops, allowing sodium to flow back into the cell along with glucose or galactose. This co-transport process requires energy, making it an active transport mechanism. The simultaneous uptake of sodium with glucose or galactose enhances the efficiency of carbohydrate absorption, particularly in the proximal small intestine.

This active transport mechanism is vital for ensuring adequate absorption of these sugars, especially since they are not readily absorbed through passive or facilitated diffusion methods commonly used by other nutrients.