Provided herein are compositions, foods comprising nepenthesin or a derivative thereof and methods of using nepenthesin or a derivative thereof for modulating gluten intolerance and related conditions, such as celiac disease. Further provided herein are pharmaceutical compositions comprising nepenthesin or a derivative thereof and methods of using nepenthesin or a derivative thereof to treat bacterial infections of the gastrointestinal tract, such as C. difficile or H. pylori. Further provided herein are compositions comprising recombinant nepenthesin I or nepenthesin II, or homologous proteins, and methods for making the same.