The present invention pertains to nutritional and pharmaceutical compositionsfor treating and preventing cyclooxygenase-2 mediated diseases and to aprocess for increasing the cyclooxygenase-2 inhibiting activity of a product.In addition thereto, the present invention relates to the use of one ore moremilk protein fractions and/or one ore more milk protein preparations forinhibiting the activity of cyclooxygenase-2 (COX-2), in particular for thepreparation of a medicament or a functional food for treating and preventingcyclooxygenase-2 mediated diseases.