Intervention: after informed consent and baseline collection of clinical data (age,sex), the participants will be randomly assigned to one of the order of the treatments. As a run-in period, they will be given a supply of probiotic or placebo tablets enough for seven days. The participants are instructed to take two tablets daily (one in the morning and one in the evening, days 0-7) and are asked to refrain from any other foods or supplements containing probiotics. On day eight, the participant will attend to the clinics and a punch biopsy will be performed. Depending on the allocation group, probiotic or placebo oil will be supplied. The participant will be instructed to apply the oil locally on the wound with a plastic microbrush for 9 days every evening, and strongly reinforced to continue with the assigned tablets twice daily. The participant will attend the clinics on days two, five and eight post-wounding for follow-up photographies of wound healing. The first intervention period terminates with a wash-out period of four weeks, and then the second run-in an intervention period start following the same procedures.