Aminopeptidase is a type of exopeptidase enzyme that catalyzes the cleavage of amino acids from the N-terminus of peptide chains. In the context of the small intestine, aminopeptidases are naturally present in the brush border membrane of enterocytes lining the intestinal wall. Their physiological role is well-documented: they participate in the final steps of protein digestion by breaking down small peptides into free amino acids, which can then be absorbed by the intestinal mucosa. This function has been validated in numerous biochemical and physiological studies, and deficiencies in aminopeptidase activity are associated with malabsorption syndromes in both humans and animal models.

The use of supplemental aminopeptidase enzymes is supported by scientific rationale, particularly in cases where endogenous enzyme production is insufficient, such as in certain digestive disorders. Some clinical and preclinical studies have evaluated the use of enzyme supplements containing aminopeptidase (often in combination with other proteases) and reported improvements in protein digestion and absorption, although the evidence base is not as extensive as for pancreatic enzymes. Nevertheless, the mechanistic basis for their use is strong, given their established role in normal intestinal physiology.

In summary, the use of aminopeptidase to support the small intestine is justified by scientific understanding of digestive physiology, and there is moderate to strong evidence for its role in protein digestion at the intestinal level.