Proteins are initially digested in the stomach to form polypeptide chains, which enter the small intestine and are finally broken down into amino acids, which are absorbed through the villous epithelium of the small intestine. Proteins are widely found in foods such as milk, meat, and eggs. Protein digestion begins in the stomach, and food digested by the stomach enters the small intestine. Proteins in the small intestine are broken down into amino acids under the action of pancreatic enzymes (trypsin, chymotrypsin, elastase, etc.) and are further digested through the hydrolytic enzymes expressed on the brush border membrane of the epithelial cells that have absorption functions. Under normal circumstances, protein digestion in the human body is mainly carried out in the small intestine. When there is a weakening of the function of the small intestine or other discomforts, it is recommended to go to a regular hospital for consultation and standardized treatment under the guidance of a doctor.