Transglutaminase inhibitor containing composition obtainable from milk, in particular from a whey fraction obtainable from skimmed milk by forming a curd from the milk, separating the curd from the whey in a centrifugation step followed by subjecting the whey to an ultrafiltration step or, alternatively, by subjecting the skimmed milk to a diafiltration step, a method for the production of a transglutaminase inhibitor and the use of the transglutaminase inhibitor in the production of food or pharmaceutical compositions and to the use in the preparation of a medicament for the treatment of pathologies.