Proteins are digested in the stomach with the aid of secretions from the pancreas and the gall bladder. Proteins not fully digested in the stomach are digested in the small intestine.
Proteins are more difficult to digest than carbohydrates, thus involving more than one digestive organ. The enzyme pepsin is essential to protein digestion in the stomach and is created when the protein pepsinogen comes in contact with hydrochloric acid. Pepsin breaks down ingested proteins into amino acids for use in the body. The pancreas, in association with the stomach, utilizes the enzymes trypsin and carboxypeptidase to further break down ingested proteins in the duodenum. Any remaining proteins are then fully digested in the small intestine.