Perception of pain and discomfort: a one-page logbook will be handed to the participants at the beginning of each run-in period so they can register the intake of tablets and their own perception of pain and discomfort according to a VAS-scale. The participant is also encouraged to register factors that could possibly influence the outcome (physical activity and number of alcoholic drinks). The participant will be asked to bring the filled logbook in the end of the intervention period.