Volunteers are asked to follow a diet plan over the whole course of the study. Every newly introduced food (in this study the dinner on days 2-5) will cause a change in biochemical marker excretion with urine. To monitor the kinetics of biomarker excretion it is necessary to collect urine several times a day; we will ask volunteers to collect the first morning urine, before lunch, before dinner and before going to bed. Urine sampling will start with the first morning urine on day 1 and end with first morning urine on day 7.