Which segment of the small intestine is the primary site for absorption of most nutrients, including water-soluble vitamins?

Which segment of the small intestine is the primary site for absorption of most nutrients, including water-soluble vitamins?

• A. Duodenum
• B. Jejunum
• C. Ileum
• D. Colon

Answer: (B)

The jejunum is the main workhorse for nutrient absorption because it provides the largest absorptive surface from its tall villi and extensive microvilli, along with many transport systems to move sugars, amino acids, minerals, and water-soluble vitamins into the bloodstream. The duodenum mostly mixes chyme with bile and pancreatic enzymes and begins digestion, while the ileum specializes in reabsorbing bile acids and the vitamin B12–IF complex. The colon mainly reabsorbs water and electrolytes and handles fermentation. Because of its vast surface area and active transport capacity, the jejunum handles the bulk of nutrient uptake, including water-soluble vitamins.

The jejunum is the main workhorse for nutrient absorption because it provides the largest absorptive surface from its tall villi and extensive microvilli, along with many transport systems to move sugars, amino acids, minerals, and water-soluble vitamins into the bloodstream. The duodenum mostly mixes chyme with bile and pancreatic enzymes and begins digestion, while the ileum specializes in reabsorbing bile acids and the vitamin B12–IF complex. The colon mainly reabsorbs water and electrolytes and handles fermentation. Because of its vast surface area and active transport capacity, the jejunum handles the bulk of nutrient uptake, including water-soluble vitamins.