Food and Salt Handling in Diuresis: Research on Effects and Mechanisms of Food and Nutrients in Urine Output and Composition

Research design: Prospective intervention study to investigate the impact of food/nutrients on urine production and fluid distribution in the body.

Study sample: The sample size was calculated for a power of 80% and for control vs. treatment using a paired-sample t-test at the 5% significance level. Thus 30 young healthy volunteers for each food group (total 300 subjects for 10 food/nutrients groups as; leek, asparagus, onion, garlic, cranberry, barley, parsley, cardamom, coffee and salt) with no acute or chronic disease, no use of medication (except contraception), not being pregnant or menstruating at the time of the study, no any food allergies and age between 20-35 years with BMI 18.5-25 kg/m2 will be included. Volunteers with an implanted electronic device (e.g. Pacemaker) will not be included.

Methodology: The subjects will be tested in fasted and sober state in the morning. No food/drink 6hrs prior to the test. The subjects will be asked to take 2 different dosages of testing nutrient and along with 500ml of water and only 500ml water for the control, on 3 different test days. Nutrients will prepared in 1g capsules. The test will last for 4 hrs after taking of the capsules.

Analyses: 3-Days food diary: Once only. For salt, caffeine and energy intake Anthropometric measurements: at the beginning of each test day 2 Blood samples at the beginning and end of the test: Haptoglobin phenotyping (serum), Haptoglobin concentration (μmol/l) (serum), Sodium (mmol/l) (serum), Osmolality (mOsm/kg) (serum), Urea (g/l) (serum), Creatinine (g/dl) (serum) 3 Urine samples at the beginning, after 2 hrs and at the end of the test: Total voided volume, Osmolality (mOsm/kg), Creatinine (g/dl), Sodium (mmol/l), Potassium (mmol/l), Urea (g/l) Bio-impedance measurement (BIA): for every 30 min for 4 hours

Sample analysis and storage: Half of the urine samples and blood samples are sent immediately after collection to the university hospital Gent clinical laboratory. The other half of the samples will be stored for a certain time in a freezer at -80 °C and will be processed and examined for a second time. The other urine samples and blood samples that are not used for the research are stored as a bio-bank.