Bone markers during a 6-month space flight: effects of vitamin K supplementation.
Rapid bone loss is a serious health problem for astronauts during long lasting missions in space. We have recorded the changes of biochemical markers for bone metabolism in one of the astronauts during the 6-month space flight of the EUROMIR-95 mission. Immediately after launch both bone resorption markers and urinary calcium excretion increased about two fold, whereas bone formation markers remained unchanged. After 12 1/2 weeks the astronaut received vitamin K1 (10 mg/day for 6 weeks). Vitamin K is known to be involved in the formation of gamma-carboxyglutamate (Gla) in proteins, such as the calcium-binding bone Gla-proteins osteocalcin and matrix Gla-protein. Concomitant with the start of vitamin K treatment, the calcium-binding capacity of osteocalcin increased, and so did the urinary excretion of free Gla. This is suggestive for a subclinical vitamin K-deficiency in the astronaut before vitamin K-supplementation. During periods of high vitamin K status markers for bone formation (osteocalcin and bone alkaline phosphatase) had increased as compared to the first part of the flight. The mean increases were 14 and 23%, respectively. Our data suggest that increased intake of vitamin K may contribute to counteracting microgravity-induced loss of bone mass during long lasting space missions, but need confirmation in more astronauts.
Vermeer
C
C
Department of Biochemistry, Maastricht University, The Netherlands. C.Vermeer@BIOCH.UNIMAAS.NL
Wolf
J
J
Craciun
A M
AM
Knapen
M H
MH
D015055:1-Carboxyglutamic Acid / Q000378:metabolism / Q000652:urine; D000328:Adult; D000337:Aerospace Medicine; D000469:Alkaline Phosphatase / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism; D015415:Biomarkers; D001846:Bone Development; D001862:Bone Resorption / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D001842:Bone and Bones / Q000201:enzymology / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism / Q000652:urine; D006801:Humans; D015675:Osteocalcin / Q000378:metabolism; D010024:Osteoporosis / Q000209:etiology / Q000517:prevention & control; D010281:Parathyroid Hormone / Q000378:metabolism / Q000652:urine; D013026:Space Flight; D014812:Vitamin K / Q000627:therapeutic use*; D010837:Vitamin K 1 / Q000627:therapeutic use; D014893:Weightlessness / Q000009:adverse effects*; D018544:Weightlessness Countermeasures
D000596:Amino Acids; D015415:Biomarkers; D010281:Parathyroid Hormone; D015675:Osteocalcin; D014812:Vitamin K; D015055:1-Carboxyglutamic Acid; D010837:Vitamin K 1; C036020:deoxypyridinoline; D000469:Alkaline Phosphatase; D002118:Calcium