The study aimed to examine the effects of an alkalinisation of a NaCl (sodium chloride, salt)-rich diet on acid base status, bone metabolism, protein turnover and other influenced physiological systems. Due to increased urinary calcium excretion and bone resorption a high NaCl-intake is considered as a risk factor for osteoporosis. On the contrary an alkaline diet is known to have a beneficial influence on bone metabolism. Therefore the investigators hypothesized that an alkaline diet can reduce NaCl-induced bone resorption. 8 healthy male volunteers took part in a stationary study carried out in the metabolic ward of the German Aerospace Center. The study consisted of 2 campaigns, each lasting 16 days. Both campaigns were divided into 5 days of adaptation, 10 days of intervention and 1.5 days of stationary recovery. During the intervention period the volunteers diet was NaCl-rich (7.7 mmol Na/kg body weight/day) and supplemented in one campaign by 90 mmol potassium bicarbonate (KHCO3) in a randomized cross-over design. The other campaign served as control. Bone metabolism was studied by bone formation markers in the fasting morning blood and 24h-urinary bone resorption markers. Acid base status was assessed by blood gas analyses in the fasted and the postprandial state as well as urinary markers. Protein turnover was studied with stable isotopes. Further physiological systems like energy metabolism and the cardiovascular system are also under investigation.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
8
7.7 mmol Na/kgBW/d + 90 mmol KHCO3
7.7 mmol Na/kgBW/d
German Aerospace Center (DLR)
Cologne, Germany
Change in daily urinary C- and N-terminal bone collagen telopeptides (mmol/d)
Time frame: Daily for a duration of 16 days
Serum concentration of bone specific alkaline phosphatase (microg/L)
Time frame: Baseline, after 3, 6, 8, 10 days of intervention, 2 days after finishing the intervention
Daily Nitrogen balance (g/d)
Time frame: Daily for a duration of 16 days
Free cortisol excretion in 24h urine (microg/d)
Time frame: Baseline, after 3, 6, 10 days of intervention
Phenylalanine hydroxylation (micromol/min)
Time frame: Baseline, end of intervention
Systolic blood pressure (bpm)
Time frame: Daily for a duration of 16 days
24h urinary net acid excretion (mEq/d)
Time frame: Baseline, end of intervention
Serum concentration of N-terminal propeptide Type I (mmol/L)
Time frame: Baseline, after 3, 6, 8, 10 days of intervention, 2 days after finishing intervention
Free cortisone excretion in 24h urine (microg/d)
Time frame: Baseline, after 3, 6, 10 days of intervention
Protein synthesis (micromol/min)
Time frame: Baseline, end of intervention
Protein degradation (micromol/min)
Time frame: Baseline, end of intervention
Diastolic blood pressure (bpm)
Time frame: Daily for a duration of 16 days
Capillary pH
Time frame: Baseline, after 3, 6, 8, 10 days of intervention, 2 days after finishing intervention
Capillary HCO3- Concentration (mmol/L)
Time frame: Baseline, after 3, 6, 8, 10 days of intervention, 2 days after finishing intervention
Capillary Base excess (mmol/L)
Time frame: Baseline, after 3, 6, 8, 10 days of intervention, 2 days after finishing intervention
Capillary pCO2 (mmHg)
Time frame: Baseline, after 3, 6, 8, 10 days of intervention, 2 days after finishing intervention
Capillary pO2 (mmHg)
Time frame: Baseline, after 3, 6, 8, 10 days of intervention, 2 days after finishing intervention
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