@article{ref1,
title="Seasonal changes in vitamin D status and bone turnover in healthy Irish postmenopausal women",
journal="International journal for vitamin and nutrition research",
year="2007",
author="Hill, Tom R. and McCarthy, Dennis and Jakobsen, J. and Lamberg-Allardt, C. and Kiely, Michele and Cashman, Kevin D.",
volume="77",
number="5",
pages="320-325",
abstract="OBJECTIVES: To examine the effect of season on biochemical markers of bone turnover in 51-to 75-year-old Irish women and to investigate whether such changes are related to vitamin D status. DESIGN: Longitudinal observational study. SETTING: Cork, Ireland (52 degrees N). SUBJECTS: 76 apparently healthy, free-living postmenopausal women (aged 51-75 years), not taking any medication and free from any condition likely to affect vitamin D status or calcium/bone metabolism. RESULTS: Serum 25-hydroxyvitamin D [S-25(OH)D] showed a clear seasonal variation with significantly higher (p < 0.001) values during late summer than late winter. Both urinary pyridinoline (Ur-Pyr) (p < 0.01) and deoxypyridinoline (Ur-Dpyr) (p < 0.001), but not serum parathyroid hormone or osteocalcin, showed a marked seasonal variation with lowest values during late-summer. Stratifying women into those with S-25(OH)D levels > or = or <50 nmol/L (vitamin D adequate and inadequate, respectively) during late-winter, showed that Ur-Pyr and Ur-Dpyr in both groups were significantly (p < 0.05) lower during late summer, and the magnitude of the reduction from winter to summer was similar in both groups. CONCLUSION: Seasonal changes in bone resorption markers appeared to be linked to seasonal changes in vitamin D status. Further research is needed to investigate the impact of these changes on risk of bone loss and fracture.<p /><p>Language: en</p>",
language="en",
issn="0300-9831",
doi="",
url="http://dx.doi.org/"
}