Where does the digestion of proteins primarily begin?

The digestion of proteins primarily begins in the stomach. When food enters the stomach, it is mixed with gastric juices that contain hydrochloric acid and pepsin, an enzyme specifically designed to break down protein molecules into smaller peptides. The acidic environment of the stomach activates pepsinogen (the inactive form of pepsin), allowing it to start the process of protein digestion. This is a crucial step as it prepares proteins for further digestion and absorption in the small intestine.

In contrast, although some digestion continues in the mouth with the action of saliva, it primarily involves carbohydrates rather than proteins. The small intestine is where the majority of nutrient absorption takes place, and pancreatic enzymes further digest proteins, but the initial process starts in the stomach. The pancreas, while involved in producing enzymes, does not directly engage in the digestion of proteins itself.