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Int J Vitam Nutr Res. 2007 Sep;77(5):320-5.

Seasonal changes in vitamin D status and bone turnover in healthy Irish postmenopausal women.

Author information

1
Department of Food and Nutritional Sciences, University College, Cork, Ireland. t.hill@ucc.ie

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.

PMID:
18453316
DOI:
10.1024/0300-9831.77.5.320
[Indexed for MEDLINE]

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