Vitamin D intake and status in Irish postmenopausal women.
OBJECTIVE
The objective of this study was to assess vitamin D status during late-summer and late-winter/early-spring in postmenopausal Irish women, and whether it was influenced by vitamin D-containing supplement use.


METHODS
A longitudinal observational study.


METHODS
Cork City, Ireland (51 degrees north).


METHODS
A total of 59 apparently healthy, free-living, postmenopausal women aged between 51 and 69 y were sampled during February/March 2002. Of these, 48 and 47 returned during August/September 2002 and February/March 2003, respectively. None of the women were suffering from any medical condition likely to affect vitamin D status. Fasting serums were collected and analysed for 25-hydroxyvitamin D (25 (OH) D) and parathyroid hormone (PTH) by enzyme immunoassays.


RESULTS
Mean daily intake of vitamin D was 3.2 microg from food sources alone and 5.8 microg when vitamin D-containing supplements were included (P<0.01). Serum 25 (OH) D was significantly lower (P<0.001) during February/March 2002 than both August/September 2002 and February/March 2003. Serum 25 (OH) D was also significantly higher (P < or = 0.05) in women who were vitamin D-containing supplement users than nonusers during all three sampling points. Between 17 and 36% of women had inadequate vitamin D status (defined as serum 25 (OH) D <40 nmol/l) during late-winter, but only 4% had inadequate vitamin D status during late-summer. Serum 25 (OH) D was inversely related to serum PTH (r = -0.33; P = 0.028).


CONCLUSIONS
Suboptimal vitamin D status is common in postmenopausal Irish women during winter. Vitamin D supplementation is associated with improved vitamin D status, even during summertime.
Hill
T
T
Department of Food and Nutritional Sciences, University College, Cork, Ireland.
Collins
A
A
O'Brien
M
M
Kiely
M
M
Flynn
A
A
Cashman
K D
KD
D000368:Aged; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D007494:Ireland / Q000453:epidemiology; D008137:Longitudinal Studies; D008875:Middle Aged; D009752:Nutritional Status; D010281:Parathyroid Hormone / Q000097:blood*; D017698:Postmenopause / Q000097:blood*; D012621:Seasons; D014807:Vitamin D / Q000008:administration & dosage* / Q000031:analogs & derivatives* / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology*
D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D