Multiple studies demonstrate that certain intact peptides and proteins can cross the intestinal epithelial barrier through paracellular transport or specific carrier mechanisms, though poor permeability and enzymatic degradation generally present significant barriers.
The retrieved literature contains multiple experimental studies showing that specific dietary and bioactive peptides (such as whey protein peptides, cricket protein peptides, and gliadin peptides) can cross the intestinal epithelial barrier intact. Therefore, the claim is supported by the provided evidence.