Nutrient absorption in small intestine

Nutrient absorption in the small intestine is a physiological process rather than a single molecule, receptor, enzyme, or transporter. The small intestine is responsible for absorbing more than 90% of nutrients and water from digested food. This occurs primarily through specialized structures called villi and microvilli that line the mucosa of the small intestine. These structures greatly increase surface area for efficient uptake. Different regions absorb different substances: - The duodenum absorbs iron. - The jejunum absorbs most carbohydrates, proteins, lipids, vitamins, and minerals. - The ileum absorbs bile acids and vitamin B12[1][3][5]. Absorbed molecules include amino acids from proteins, monosaccharides from carbohydrates, fatty acids/glycerol from fats—each entering either blood capillaries or lymphatic lacteals within villi[1][2]. Mechanisms include passive diffusion (water/lipids), facilitated diffusion (fructose), active transport/co-transporter systems (glucose/amino acids), and paracellular pathways. Disorders affecting this process can lead to malnutrition or specific deficiencies. While many drugs can influence nutrient absorption by altering motility or mucosal health—or by targeting specific transporters—there is no single drug that targets “nutrient absorption” as if it were one molecular entity. Because “nutrient absorption in small intestine” refers to an integrated physiological function involving many cell types and molecular mechanisms—not a discrete therapeutic target—the entry should be marked as incorrect for use as a canonical drug discovery target[1][3].

Other names

Absorption in the small intestineIntestinal nutrient absorptionSmall intestinal absorption