Salty Life 7 Study: Effect of High Salt Intake on Several Physiological Systems in Immobilisation (SL7)

German Aerospace Center (DLR)

Status: Completed

Conditions: Electrolyte Metabolism; Acid-Base Metabolism; Energy Metabolism; Bone Metabolism; Circulation System

Treatments: Other: Dietary salt intake

Study type: Interventional

Funder types: Other

Identifiers

NCT01183299

DLR-2005049

Details and patient eligibility

About

The Salty Life 7 study aimed to examine the effect of a high salt (sodium chloride, NaCl) intake on different forms of sodium retention, acid-base balance and bone metabolism and other influenced physiological systems. Because of the fact that astronauts are a vulnerable group in this context, they were of special interest. Astronauts have a high salt intake, probably because of a reduced sense of taste, as well as an increased bone resorption resulting from the lowered mechanical load in space. In which forms sodium could be retained even without fluid retention (osmotically inactive)- contrary to the argumentation of physiological text books - and if the acid-base balance is connected to sodium chloride induced bone loss is examined in a stationary bed rest study with 8 healthy, young, male test subjects. The study consisting of 2 x 21 days is carried out at the German Aerospace Center (DLR). After an adaptation period of 4 days, test subjects are immobilised in 6° head-down tilt bed rest (simulation model for some physiological changes in space) for 14 days during which they received a high (7.7 mmol NaCl/kgBW/d) and a low salt (0.7 mmol NaCl/kgBW/d) intake in cross-over design. The form of sodium retention is investigated by the calculation of daily metabolic sodium-, water- and potassium balances and by changes in body weight. The measurements of bone formation (bAP, PINP, Osteocalcin) markers as well as bone resorption markers (CTX, NTX) supply insight into the influences of a high salt intake on bone metabolism. Blood gas analysis and ph values of 24-h urine are used to gather information about accompanying changes in the acid-base balance. Further physiological systems like energy metabolism and circulation system are also under investigation.

Enrollment: 8 patients

Sex: Male

Ages: 20 to 35 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Male
• Age: 20-35 years
• Weight: 65±85kg
• Height:180±10cm.
• Successfully completed medical & psychological screening

Exclusion criteria

• Drugs- and alcohol abuse
• Hyperlipidemia
• Obesity
• Renal diseases
• Participant of another study in the same time frame and 3 months before starting the study
• Blood donation within the last three months before starting the study
• Risk for thrombosis
• Smoking
• Diabetes
• Rheumatism
• Bone Fracture

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: None (Open label)

---

8 participants in 2 patient groups, including a placebo group

High salt intake

Active Comparator group

Treatment:

Other: Dietary salt intake

Low salt intake

Placebo Comparator group

Treatment:

Other: Dietary salt intake