Aspergillopepsin is a protein-digesting enzyme made from the fungus *Aspergillus niger*. It cuts proteins into smaller peptides and amino acids. You sometimes find it in digestive enzyme blends, where it assists with protein breakdown. People often take it alongside protein-containing meals when they feel they need extra digestive help.
Since the enzyme comes from a mold, anyone with a mold allergy, asthma, or a weakened immune system should be careful. Protease enzymes can also irritate the stomach lining, a particular risk for those with gastritis or peptic ulcers.