An, 18 weeks, one-armed cross over intervention trial consisting of a 6-weeks pre-intervention period, 6-weeks intervention period and a 6-weeks post-intervention period. 25 healthy young men will be included in the trial. The pre-intervention period is the control period with no treatment. During the intervention period participants will receive 500 mg of metformin once daily the 1st week, then 500 mg twice daily the 2nd week, 1000 mg + 500 mg daily the 3rd week and 1000 mg + 1000 mg daily the remaining three weeks. Post-interventional investigators will examine gut microbiota of the participants 6 weeks after completion of the intervention period.~MESUREMENTS: Altered composition of gut microbiota as investigated by 16S rRNA sequencing is the primary outcome of this study. Secondary outcomes are to investigate changes in metabolic and inflammatory markers in blood and fecal samples. Blood, urine, saliva and fecal samples will be stored for future studies.
OBJECTIVE: Investigate structural changes in the human gut microbiota and associated changes in metabolic markers in urine, saliva, blood and fecal samples following metformin treatment.~DESIGN: An, 18 week, one-armed cross over intervention trial consisting of a 6-week pre-intervention period, 6-week intervention period and a 6-week post-intervention period. 25 healthy young men will be included in the trial.~INTERVENTION: Six-week Metformin treatment to young healthy men.