What is responsible for the breakdown and absorption of nutrients

In the stomach, enzymes break down food such as carbohydrates, protein and fats, so that nutrients can be absorbed farther down the GI tract, according to the National Digestive Disease Information Clearinghouse. The stomach mixes and churns foods to slowly release into the small intestine. Liquids empty the quickest, in one to two hours, and solid food takes about two to three hours to transit out of the stomach.