Randomization and blinding
Randomization was 1:1 with twelve persons in each group. Randomization was done by drawing a folded paper with treatment allocation (12 placebo and 12 study capsule), from a sealed envelope. The paper slips with treatment allocation and sealed envelope were made by a member of the laboratory staff prior to study start. Randomization was done by the laboratory staff that manufactured placebo or study capsules. The laboratory was located several kilometres from the hospital and there was no direct contact between laboratory and hospital study staff.Identical white capsules were delivered in sealed white plastic containers labelled with the study participants name and study id. Peppermint oil was added to the inside lid of the containers to ensure a non-revealing smell.