The Effect of Potassium Bicarbonate on Bone and Several Physiological Systems During Immobilisation (NUC)

February 28, 2017 updated by: DLR German Aerospace Center

The Effect of Potassium Bicarbonate on Bone and the Immune System During 21 Days of 6° Head- Down- Tilt Bedrest (HDT- Bedrest)

Mainly due to the absence of gravitational forces in weightlessness, astronauts suffer from an increased bone loss- negatively affecting health and vitality during a mission. The development of effective countermeasures to this loss includes many different aspects like sports but also nutrition.

Alkaline salts, abundant in fruits and vegetables, have shown to have positive effects on markers of bone turnover of postmenopausal women but also men and younger adults. With the current study the effects of a potassium bicarbonate supplementation added to a standardised, strictly controlled, definite diet of healthy, young men, should be verified within 21 days of 6°- HDT- Bedrest- the gold standard of simulating weightlessness within earthbound conditions.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Astronauts in space suffer from an increased bone loss which is mainly related to the absence of gravitational forces. This increased bone reduction is accompanied by an higher concentration of calcium in urine and in this respect enhancing the risk of renal stones. Due to the fact, that bones´ regeneration does not occur rapidly even after returning to earth, astronauts face an increased risk of osteoporosis.

Nutritional factors such as a deficient intake of calcium, energy and fluid and the abundant intake of table salt exhibit additional negative effects on bone. Results of several studies consistently show the negative effects of acids on bone (increased bone loss). With respect to space missions of longer duration one big challenge is the development of countermeasures for the negative consequences of weightlessness on bone.

As not all needed experiments for the development of countermeasures can be conducted in space, simulation models of weightlessness such as 6° Head- Down- Tilt- Bedrest (HDT- Bedrest) have been implemented on earth, miming some physiological conditions of weightlessness such as unloading and immobilisation of the lower parts of the body and the fluid shift.

Alkaline salts, such as potassium bicarbonate (KHCO3), demonstrate positive effects on bone when being supplemented to postmenopausal women. Apart from the positive effects on markers of bone turnover, calcium concentration in urine could be reduced. Thus, the main aim of the present study was to reduce the immobilization induced bone resorption through an alkalizing effect of the alkaline salt KHCO3's supplementation during Head- Down- Tilt- Bedrest (HDT- Bedrest)-a leading simulation model of weightlessness.

The crossover designed study consisted of two parts of equal length (36 days)- 7 days of adaptation, 21 days of HDT- Bedrest, 6 days recovery and 2 days of long- term follow- up. Both study parts only differed in the HDT- period, where one group of the 8 healthy, young, male participating subjects was supplemented with 90 mmol KHCO3 daily (3 times a day 30 mmol KHCO3 diluted in 200 ml tab water, supplemented together with the main meals), while the other group only received 200 ml of tab water without any supplementation (Control group).

The measurements of bone formation markers as well as bone resorption markers in blood and urine supply insight into the influences of the supplementation on bone metabolism while blood gas analysis together with the pH- values of the 24h- urine point out the alkalising effects of KHCO3. Further physiological systems like protein and muscle metabolism, body weight and body composition, circulation and the neuro- vestibular system are simultaneously under investigation.

Study Type

Interventional

Enrollment (Actual)

8

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Germany
      • Cologne, Germany, 51147
        • German Aerospace Centre (DLR)

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

20 years to 45 years (ADULT)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

Male

Description

Inclusion Criteria:

  • healthy male subjects
  • age: 20- 45
  • weight 65- 85 kg
  • height: 158- 190 cm
  • BMI 20- 26 kg/m2
  • no high performance sports
  • non- smoking (minimum 6 months prior to study start)
  • willing to complete both parts of the study
  • presentation of social security and criminal record
  • successful completion of medical and psychological screening
  • signed informed consent

Exclusion Criteria:

  • drugs- and alcohol abuse
  • antiinflammatory drugs taken during the study
  • vegetarianism, veganism
  • migraine
  • psychical illness in the past
  • claustrophobia
  • hiatal hernia
  • gastroesophageal reflux
  • diabetes mellitus
  • Rheumatic disease
  • muscle or joint disease
  • disc prolapse
  • orthostatic intolerance
  • Hyperlipidaemia
  • renal disease
  • thyroid dysfunction
  • hyperhomocysteinaemia
  • hyper-/hypouremia
  • hyper-/hypocalcemia
  • anaemia
  • hypoferremia
  • Vitamin D deficiency
  • deviation of blood gases from normal values (pH 7,38 - 7,42; pO2 79 - 98 mmHg; pCO2 34 - 45 mmHg; HCO3 20 - 28 mmol/l; Base excess ± 2 mmol/l)
  • risk of thrombosis
  • chronic back pain
  • bone fracture within one year prior to study start
  • bone mineral density 1,5 SD ≤ t-Score
  • metal implants or other osteosynthesis material
  • subject within another clinical trial within 2 months prior to study start
  • any other status which according to the apprehension of the principal investigator leads to the exclusion of the subject

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: BASIC_SCIENCE
  • Allocation: RANDOMIZED
  • Interventional Model: CROSSOVER
  • Masking: NONE

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
NO_INTERVENTION: Control
ACTIVE_COMPARATOR: Potassium Bicarbonate
Dietary supplement: Potassium Bicarbonate
90 mmol daily, effervescent tablets 30 mmol diluted in 200 ml tab water supplemented three times a day together with the main meals for 21 days of HDT- bedrest

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
The reduction of the immobilisation induced bone loss by supplementing an alkaline salt (potassium bicarbonate)
Time Frame: 21 days of HDT- Bedrest
21 days of HDT- Bedrest

Secondary Outcome Measures

Outcome Measure
Time Frame
Influence of KHCO3 on bone mass, bone mineral density and bone strength
Time Frame: 21 days of HDT- Bedrest
21 days of HDT- Bedrest
Determination of effects of KHCO3 on muscle strength, muscle power and muscle volume
Time Frame: 21 days of HDT- Bedrest
21 days of HDT- Bedrest
Determine the effects of KHCO3 on body composition and body weight
Time Frame: 21 days of HDT- Bedrest
21 days of HDT- Bedrest
Determine the effects of KHCO3 on the cardiovascular system
Time Frame: 21 days of HDT- Bedrest
21 days of HDT- Bedrest
Determine the effects of KHCO3 on the neuro- vestibular system
Time Frame: 21 days of HDT- Bedrest
21 days of HDT- Bedrest
Determination of effects of KHCO3 on protein and muscle turnover
Time Frame: 21 days of HDT- Bedrest
21 days of HDT- Bedrest

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

DLR German Aerospace Center

Collaborators

University of Aarhus
University of Trieste
European Space Agency

Investigators

  • Principal Investigator: Francisca May, Dr., German Aerospace Centre, Institute of Aerospace Medicine (DLR)

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

February 1, 2010

Primary Completion (ACTUAL)

October 1, 2010

Study Completion (ACTUAL)

October 1, 2010

Study Registration Dates

First Submitted

July 4, 2011

First Submitted That Met QC Criteria

January 10, 2012

First Posted (ESTIMATE)

January 13, 2012

Study Record Updates

Last Update Posted (ACTUAL)

March 1, 2017

Last Update Submitted That Met QC Criteria

February 28, 2017

Last Verified

February 1, 2017

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • AO-2004-068 (MAP)

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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