Skip to page content Mission Information


Dietary Intake Can Predict and Protect Against Changes in Bone Metabolism during Space Flight and Recovery (ProK)
Principal Investigator
Research Area:
Metabolism and nutrition
Skeletal physiology
Species Studied
Scientific Name: Homo sapiens Species: Human

This study proposed that a diet with a decreased ratio of animal protein to potassium will lead to decreased bone resorption and bone mineral loss during space flight. The study goals were to validate the hypothesis that modification of dietary intake patterns can minimize bone loss and postflight recovery time by determining if the ratio of acid (animal protein) to base (potassium) precursors in the diet is correlated with markers of bone formation and bone resorption during space flight. Specifically, the researchers wanted to determine the extent to which urinary calcium excretion predicts changes in bone metabolism from acid and base precursors in the diet. They also wanted to determine if the ratio of acid to base precursors in the diet is related to the length of time required for recovery from bone mineral loss after space flight.

++ -- View more

Zwart SR, Rice BL, Dlouhy H, Shackelford LC, Heer M, Koslovsky M, Smith SM. Dietary acid load and bone turnover during long-duration spaceflight and bed rest. American Journal of Clinical Nutrition. 2018. May (107); 5, 834–844, [DOI]

Bone demineralization, pathologic
Bone resorption

Photo Gallery
+ View digital images

Data Information
Data Availability
Archive is complete. Data sets are not publicly available but can be requested.
Data Sets+ Request data

Animal protein
Body composition
Body mass
Body weight
Bone composition
++ -- View more

Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Expedition 22 11/30/2009 03/18/2010 109 days
Expedition 23 03/18/2010 06/01/2010 75 days
Expedition 24 06/01/2010 09/25/2010 117 days
Expedition 25 09/24/2010 11/25/2010 31 days
Expedition 26 11/26/2010 03/16/2011 111 days
Expedition 27 03/14/2011 05/23/2011 70 days
Expedition 30 11/14/2011 04/27/2012 166 days
Expedition 31 04/27/2012 07/01/2012 65 days
Expedition 32 07/01/2012 09/16/2012 78 days
Expedition 33 09/16/2012 11/18/2012 63 days
Expedition 34 11/18/2012 03/15/2013 117 days
Expedition 35 03/15/2013 05/13/2013 58 days
Expedition 36 05/13/2013 09/10/2013 166 days
Expedition 37 09/10/2013 11/10/2013 61 days
Expedition 38 11/10/2013 03/10/2014 120 days
Expedition 40 05/13/2014 09/10/2014 133 days
Expedition 41 09/10/2014 11/09/2014 29 days

Human Research Program (HRP) Human Research Roadmap (HRR) Information
Crew health and performance is critical to successful human exploration beyond low Earth orbit. The Human Research Program (HRP) investigates and mitigates the highest risks to human health and performance, providing essential countermeasures and technologies for human space exploration. Risks include physiological and performance effects from hazards such as radiation, altered gravity, and hostile environments, as well as unique challenges in medical support, human factors, and behavioral health support. The HRP utilizes an Integrated Research Plan (IRP) to identify the approach and research activities planned to address these risks, which are assigned to specific Elements within the program. The Human Research Roadmap is the web-based tool for communicating the IRP content.

The Human Research Roadmap is located at:

+ Click here for information of how this experiment is contributing to the HRP's path for risk reduction.

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Jessica Keune
Institutional Support
National Aeronautics and Space Administration (NASA)
Alternate Experiment Name
Pro K
Proposal Date
Proposal Source