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Title: Vitamin K status in spaceflight and ground-based models of spaceflight

Author
item Zwart, Sara R. - Universities Space Research Associaton
item Booth, Sarah L. - Jean Mayer Human Nutrition Research Center On Aging At Tufts University
item Peterson, James W. - Jean Mayer Human Nutrition Research Center On Aging At Tufts University
item Wang, Zuwei - Enterprise Advisory Services
item Smith, Scott M. - National Aeronautics And Space Administration (NASA)

Submitted to: Journal of Bone and Mineral Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/12/2010
Publication Date: N/A
Citation: N/A

Interpretive Summary: Bone loss is a well-documented change during and after long-duration space flight. Many types of measures that counteract bone loss have been proposed, including vitamin K supplementation. The objective of this series of studies was to measure change in vitamin K in response to a variety of space flight and space flight model conditions. Among crew members who flew 2–6 months on the International Space Station, measures of circulating vitamin K concentrations taken during and after space flight did not change from concentrations measured before crew members were in flight. Consistent with this finding, other measures of vitamin K status that reflect how vitamin K is utilized in the body did not change in response to flight. Space flight findings were corroborated by findings of no changes in measures of vitamin K status in four separate studies (14–90 days in duration) in which gravity was manipulated to mimic the effects of space flight. The data presented here do not support a need for vitamin K supplementation during spaceflight nor support the suggestion of using vitamin K as a supplement to counteract bone loss that occurs in space flight.

Technical Abstract: Bone loss is a well-documented change during and after long-duration spaceflight. Many types of countermeasures to bone loss have been proposed, including vitamin K supplementation. The objective of this series of studies was to measure change in vitamin K status in response to microgravity under a variety of spaceflight and spaceflight analogue (model) conditions, including long-duration spaceflight studies (n = 15), three bed rest studies (n = 15, 51, and 24), and a 14-day saturation dive (n = 6). In crew members who flew 2–6 months on the International Space Station, in-flight and postflight plasma phylloquinone concentrations were unchanged from the preflight mean. Consistent with this finding, urinary gamma-carboxyglutamic acid (GLA), a measure of vitamin K-dependent protein turnover, and serum undercarboxylated osteocalcin (%ucOC), a measure of vitamin K function, did not change in response to flight. Spaceflight findings were corroborated by findings of no changes in phylloquinone, urinary GLA, or %ucOC during or after bed rest in three separate bed rest studies (21–90 days in duration) or after a 14-day saturation dive. The data presented here do not support either a need for vitamin K supplementation during spaceflight or the suggestion of using vitamin K as a bone loss countermeasure in spaceflight.