39 healthy subjects without medication (except oral contraceptives) aged 20-70 years are recruited via advertisements or through telephone contacts with individuals that had previously participated in population-based cohort studies in Malmö. All subjects are exposed to three different intervention procedures; water and coffee loads (acutely and chronically), or no change from usual fluid intake (as a time-control), respectively in randomized order. The daily intake of coffee or water will amount to 3 L of water and 1 L of coffee, respectively for one week each. The three interventions (water, coffee and control), are separated by three weeks of normal fluid intake as a wash-out period.

By testing if simple life style interventions, i.e., increased water or coffee intake, may affect vasopressin secretion, evaluated as copeptin, we will increase the knowledge as to whether such life style induced changes of copeptin may in turn lead to effects on glucose tolerance as well as on other cardiometabolic risk factors previously shown to be associated with high copeptin level. Thus, the study will lead to further understanding about vasopressin and copeptin release and how life style manipulation of the vasopressin system may influence glucose metabolism and other cardiometabolic risk factors in healthy individuals.

Day 1: The initial examination consists of medical history, clinical examination including office blood pressure, and blood sampling (overnight fasting plasma copeptin (a marker of vasopressin), osmolality, insulin, glucagon, glucose, creatinine, hsCRP and OGTT), and start of 24-h urine collection and 24-h ambulatory blood pressure measurement.

Day 2: After completion of the 24-h urine collection and ABPM, in the fasting state in the morning, office blood pressure will be measured and blood sampling for plasma copeptin, osmolality insulin, glucagon, glucose, creatinine and hsCRP measurement will be performed. Then, during a maximum time period of 20 minutes, subjects will ingest either 1L of water or 4 dL of coffee, or just 10 ml of water (time control). To map the acute coffee or water effect on copeptin, the experiment proceeds with repeated blood sampling every 30 minutes for 4 hours after the first coffee or water intake. Day 1 then continues with the rest of the daily intake, i.e., 2 L of water or 6 dL of coffee in addition to normal food and fluid intakes.

Day 3 to 7: 3 L water per day or 1 L of coffee per day are ingested (or nothing, in the control intervention) in addition to each subject's own food and fluid intake. On days 4 and 6, blood sampling for electrolyte and urea measurement and osmolality will be carried out for reasons of safety and compliance check.

Day 8: Fasting in the morning, office blood pressure, blood sampling (copeptin, osmolality, insulin, glucagon, glucose, creatinine, hsCRP) will be performed and a 24-h urine collection and ABPM will be started.

Day 9: The final examination will consist of clinical examination including office blood pressure and blood sampling (overnight fasting plasma copeptin, osmolality, insulin, glucagon, glucose, creatinine, hsCRP and OGTT), and end of 24-h urine collection and ABPM.

Inclusion Criteria:

Healthy subjects Age 20-70 years

Exclusion Criteria:

medication (except oral contraceptives) any type of acute illness any type of chronic illness