How does food become nutrients the body can use?

Food travels through a tube from the mouth to the stomach and intestines. Digestion breaks food into smaller parts. Absorption is different: small nutrients cross the small-intestine wall into the body. The gut tube and the blood route are separate. Blood can then carry absorbed nutrients toward body cells. Digestion and absorption are different processes. Digestion reduces food to smaller molecules; absorption moves those molecules across the intestinal lining. Most absorption occurs in the small intestine, supported by secretions from several organs. Many nutrients reach the blood circulation for delivery to tissues, while some fat products travel first through lymph. Water recovery continues in the large intestine.