Gluten-Digesting Enzymes

Prolyl endopeptidase · AN-PEP · Aspergillus niger prolyl endoprotease · Prolyl endoprotease

Snapshot

Indications	Contraindications
Inadvertent gluten exposure¹ Celiac disease symptoms¹ Gluten-induced malabsorption² Non-celiac gluten sensitivity³	Substitute for gluten-free diet^{3, 4} Warfarin with vitamin K products⁵

Gluten-digesting enzymes are oral proteases, chiefly Aspergillus niger prolyl endopeptidase (AN-PEP), that cleave proline-rich gluten peptides during digestion. People take them to limit the effects of gluten that slips past a gluten-free diet, mainly celiac disease patients and those with non-celiac gluten sensitivity.

Results are mixed. A 2024 randomized trial in celiac patients on a long-term gluten-free diet found no significant fall in stool gluten peptides, though fewer patients were symptomatic than at run-in. Pretreating gluten with the enzyme avoided fat or carbohydrate malabsorption in most patients who developed it after a gluten challenge². In non-celiac gluten sensitivity, a randomized trial found no effect on symptoms. In a 2025 simulated-digestion study of pizza, a prolyl-endopeptidase supplement degraded immunotoxic gluten epitopes fastest among three products, yet none abolished the response of celiac-derived T cells; it was a laboratory model, not a clinical trial⁶. Many products listing gluten-digesting enzymes are sold, often blended with other digestive enzymes; see Form comparison.

The consequential limit is incomplete degradation: some celiac patients still developed malabsorption on enzyme-treated gluten². United States product labels warn that vitamin K in some formulations may interact with warfarin, a warning on 1 of 21 labels reviewed⁵.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

12 sources, 10 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources