In the human body, which organ is the primary site of nutrient absorption?

The small intestine is the primary site of nutrient absorption in the human body.

Most chemical digestion is completed there, and its lining is folded into circular folds, villi, and microscopic microvilli. These structures greatly enlarge the surface available for absorbing digested carbohydrates, proteins, fats, vitamins, minerals, and water. Absorbed nutrients then enter blood capillaries or lymphatic vessels.

The small intestine is divided into the duodenum, jejunum, and ileum. The duodenum receives partially digested food from the stomach, along with bile and pancreatic secretions. The large intestine absorbs additional water and electrolytes and helps form feces, but it is not the main location for absorbing energy-providing nutrients. The stomach begins digestion, especially of proteins, but its absorptive role is comparatively limited.