How does digestion break food proteins into amino acids?

The digestion of protein is a process of proteolysis, where complex protein molecules are broken down into peptides and eventually into individual amino acids through hydrolysis.123

This process occurs in stages:

• Stomach: Protein digestion begins here, where the enzyme pepsin (secreted as the inactive precursor pepsinogen) acts in an acidic environment to perform partial degradation of proteins into smaller peptide units.1452
• Small Intestine: The majority of protein digestion occurs in the duodenum and upper jejunum. The pancreas secretes powerful proteolytic enzymes—such as trypsin, chymotrypsin, and elastase—as inactive precursors that are activated in the intestine.52
• Final Breakdown: These enzymes, along with carboxypeptidases, further break down peptides into smaller chains and finally into single amino acids. This process continues at the brush border and within the enterocytes of the intestinal wall, allowing the resulting amino acids to be absorbed into the bloodstream.52