Patients will be investigated for all the markers at the beginning of the study (T0) and then randomized using a computer-generated list (StatsDirect statistic program) in two groups, with either 4 coffee cups/day intake for 1 month or abstinence for the same time period. Obviously, blinding is not possible and we decided not to prescribe any wash-out period, being the T0 sampling examined in relation to the patients' routine coffee consumption.