Vitamin D status of 51-75-year-old Irish women: its determinants and impact on biochemical indices of bone turnover.
OBJECTIVE
To assess the vitamin D status of Irish postmenopausal women during wintertime, and to examine its relationship with serum parathyroid hormone (PTH) and biochemical markers of bone turnover. In addition, the determinants of wintertime serum 25-hydroxyvitamin D (25OH-D) levels in these women were investigated.


METHODS
A cross-sectional observational study.


METHODS
Cork City, Ireland (52 degrees N).


METHODS
Ninety-five 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
Forty-eight per cent and 7% of women had serum 25OH-D levels <50 nmol l(-1) and <25 nmol l(-1), respectively. 25OH-D levels in these women were positively associated with dietary calcium intake (P = 0.0002) and use of vitamin D-containing supplements (P = 0.031), and negatively associated with cigarette smoking (P = 0.027) and body mass index (BMI) (P = 0.030). Low serum 25OH-D levels (<50 nmol l(-1)) were associated (P < 0.01) with elevated serum PTH levels. There were no significant differences in urinary pyridinium crosslinks or serum osteocalcin, biochemical indices of bone turnover, between subjects with serum 25OH-D levels above or below 50 nmol l(-1).


CONCLUSIONS
A high proportion of Irish postmenopausal women had low vitamin D status (<50 nmol l(-1)) during late wintertime, which appeared to lead to elevated levels of serum PTH but not of bone turnover markers. Use of regular low-dose supplemental vitamin D, meeting daily calcium recommendations, cessation of smoking and maintaining BMI in the normal range are important factors that could help maintain adequate vitamin D levels during wintertime in these women.
Department of Food and Nutritional Sciences, University College, Cork, Ireland.
Tom R
TR
Hill
Maria M
MM
O'Brien
Christel
C
Lamberg-Allardt
Jette
J
Jakobsen
Mairead
M
Kiely
Albert
A
Flynn
Kevin D
KD
Cashman
D000368:Aged; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D050071:Bone Density Conservation Agents / Q000097:blood*; D001842:Bone and Bones / Q000378:metabolism*; D002136:Calcium, Dietary / Q000008:administration & dosage*; D003430:Cross-Sectional Studies; D019587:Dietary Supplements; D005260:Female; D006306:Health Surveys; D006801:Humans; D007494:Ireland / Q000453:epidemiology; D008875:Middle Aged; D009752:Nutritional Status; D010281:Parathyroid Hormone / Q000097:blood*; D017698:Postmenopause; D012621:Seasons; D012907:Smoking / Q000009:adverse effects; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000453:epidemiology*; D016387:Women's Health
D015415:Biomarkers; D050071:Bone Density Conservation Agents; D002136:Calcium, Dietary; D010281:Parathyroid Hormone; D014807:Vitamin D