Table 1.

Absorption mechanisms of dietary carbohydrates and specific drugs available to facilitate digestion.

Carbohydrate	Type	Absorption Mechanisms	Available Specific Drugs
Monosaccharides	Fructose	Absorption of excess fructose occurs in the small intestine: rapidly via GLUT-2, the sodium-dependent active transport mechanism in conjunction with glucose; slowly via GLUT-5, a specific transporter for fructose using carrier-mediated facilitated diffusion. Thus, fructose is well-absorbed in the presence of equimolar glucose in the proximal small intestine, whereas free fructose is absorbed slowly along the length of the small intestine.	Xylose-isomerase
Disaccharides	Lactose Sucrose	Unabsorbed in small intestine if lactase is absent. Unabsorbed in small intestine in case of sucrase-isomaltase deficiency	Lactase Sacrosidase
Oligosaccharides	FOS * GOS	Humans do not possess small intestinal hydrolases to hydrolyse oligosaccharides, and they are unabsorbed.	None
Polyols	Sorbitol Mannitol Maltitol Isomalt Lactitol Xylitol	Sugar alcohols are poorly absorbed along the length of the small intestine by slow passive diffusion.	None

* FOS: Fructo-oligosaccharides; GOS: Galacto-oligosaccharides.