Postprandial Response of Individuals to Dietary Inorganic Phosphate

It is a monocentric, controlled intervention trial. The study will be carried out in cross-over design. This design was chosen because of a moderately strong individual metabolic response to the test meal.

Two interventions are planned in which the subjects will receive a test meal with phosphate supplement or with placebo in random order on 2 days. Subjects will be randomized to one of the 2 treatment arms.

On the two intervention days (T1 and T2), the subjects are placed a venous indwelling cannula. Immediately after the first blood sample the subjects take the fat and carbohydrate-rich test meal along with 700 mg of phosphorus or a placebo, both in the form of capsules. Phosphorus is administered as sodium phosphate . The placebo used is sodium chloride with equivalent amounts of sodium. The filler should be silica and mannitol. The capsules are made of hard gelatin and dissolve in about 10 minutes. The capsules are taken with 300 ml of water. The verum and placebo capsules are produced by the central pharmacy of the University Hospital.

The test meal consists of a pasta dish with oily tomato sauce. It is freshly prepared by the study staff and packaged airtight in individual portions before being handed out to the subjects. The test meal should be consumed within 10 - 12 minutes. The time is documented by the study staff. The next blood sample is taken immediately after the end of consumption (time 0), all other 15, 30, 45, 60, 90, 120, 180, 240, 300, 360, 420 and 480 minutes thereafter. All blood samples are taken in a lying position. The first 3 hours after eating the test meal the subjects should spend reclining. In the following 5 hours subjects are free to move in the study center with each patient taking a recumbent position 10 minutes before the next blood draw. Immediately before all blood samples are taken the measurement of blood pressure and pulse is provided for which the opposite arm is to be used. Furthermore the collection of urine samples is provided every hour. Subjects are encouraged to take 200 ml of water every hour on the intervention day. At the end of the intervention, a snack will be provided.

Inclusion criteria

• healthy men and women
• age between 18 and 60 years
• informed consent
• body mass index between 18,5 up to 29,9 kg/m2
• anamnesis without diagnostic findings

Exclusion criteria

• Participants with epidermal growth factor receptor (eGFR) < 90 ml/min and chronic kidney disease
• Subjects suffering from vitamin D-deficiency (plasma 25(OH)D < 30 nmol/l)
• Pregnancy or lactation
• Subjects with any acute or chronic diseases (infection, tumor, cardiovascular diseases, respiratory diseases, inflammatory diseases), gastrointestinal diseases, diabetes mellitus type 1 and 2, bone diseases, diseases of the parathyroid gland
• Use of medication
• Use of dietary supplements (minerals)
• Relevant food allergies (wheat protein, tomatoes)
• Weight reduction
• Smokers
• Blood donor in the last 3 months
• Participation in another intervention study