When subjected to fluid loss or fluid deficiency irrespective of disease or environmental factors it is discussed how to rehydrate or how to hydrate prophylactic.

In medical care it is common to give infusions. However it has increasingly become common to hydrate the patient through the mouth even early after bowel surgery. Moreover it is more simple to provide energy the natural way.

Which fluid to give, depends on several factors such as possibility to drink, the volume and emptying of the stomach as well as the fluid absorption in the bowel.

The provided fluid can also influence this process depending on temperature, osmolality/tonicity and composition (carbohydrates or salts).

In this study we wish to study the speed with which the provided fluid is absorbed by the bowels and how fast the fluid is distributed to the different body compartments depending on it's composition.

The three fluids will be either tap water, high sodium chloride and a carbohydrate rich fluid.

The healthy volunteer starts the study by voiding. Then he/she lies down for 30 minutes. A blood sample is drawn and thereafter the healthy volunteer ingests one of the three fluids. Blood samples are drawn 10 times during the following two hours. Finally the healthy volunteer is asked to void and the voided urine is measured. The hemoglobin concentrations are used to calculate the blood volume expansion with volume kinetic methods.

The process is repeated another two times with the two remaining fluids.

Inclusion Criteria:

• healthy volunteer
• 18 to 50 years old

Exclusion Criteria:

• medication
• any chronical disease