Food and Salt Handling in Diuresis

Plain-language summary

Understanding the impact of food/nutrients on body fluid metabolism is important for improving diagnosis and treatment of nocturia, polyuria in relation to lifestyle interventions. This study on "Food and Salt Handling in Diuresis" examines the role of certain food and nutrients in diuresis. The study design is to investigate the possible acute effects and mechanisms of selected food (which are known to be diuretic) and nutrients (e.g. salt) in diuresis in healthy individuals. The study will provide insights into the management of nocturia, nocturnal polyuria or oedema which are common clinical sign in a wide range of disorders as cardiovascular, renal and metabolic disorders. During the study the volunteers will be asked to ingest a certain dosage of a food/nutrient in capsules along with a defined amount of water (500 ml). 2 Blood and 3 urine samples will be collected at different time points to measure the urine output and urine composition derived by the ingestion of the particular food item. Renal Function Profiling is used as an easy and cheap tool to understand the mechanism of action behind the observed effect in diuresis. Renal function profiles distinguish the osmotic form water diuresis from a change in filtration. Bio-electrical impedance analysis (BIA) is also used to evaluate oedema and fluid volumes in body tissues. BIA is a non-invasive technique based on Ohm's law whereby the resistance of a tissue against an electric current is inversely proportional to the water content and directly proportional to the length of the tissue. For the BIA measurement, a device is used in which 8 tactile electrodes are placed: 2 in contact with the thumb and middle finger of each hand, and 2 in contact with the inside and outside of each foot. Before the start of the measurements, the length and body weight are measured. The resistance of the arms, torso and legs is measured at different frequencies.

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