Sunlight and dietary contributions to the seasonal vitamin D status of cohorts of healthy postmenopausal women living at northerly latitudes: a major cause for concern?

H. M. Macdonald, A. Mavroeidi, W. D. Fraser, A. L. Darling, A. J. Black, L. Aucott, F. O'Neill, K. Hart, J. L. Berry, S. A. Lanham-New, D. M. Reid

Research output: Contribution to journalArticle

108 Citations (Scopus)

Abstract

Summary
We assessed sunlight and dietary contributions to vitamin D status in British postmenopausal women. Our true longitudinal 25-hydroxyvitamin D (25(OH)D) measurements varied seasonally, being lower in the north compared to the south and lower in Asian women. Sunlight exposure in summer and spring provided 80% total annual intake of vitamin D.
Introduction
Vitamin D deficiency is highlighted as a potential problem for countries at high latitude, but there are few true longitudinal, seasonal data to allow regional comparisons. We aimed to directly compare seasonal variation in vitamin D status (25(OH)D) in postmenopausal women at two northerly latitudes and to assess the relative contributions of sunlight exposure and diet.
Methods
Vitamin D status was assessed in 518 postmenopausal women (age 55–70 years) in a two-centre cohort study with serum collected at fixed three-monthly intervals from summer 2006 for immunoassay measurement of 25(OH)D and parathyroid hormone. At 57° N (Aberdeen, Scotland, UK), there were 338 Caucasian women; at 51° N (Surrey, South of England, UK), there were 144 Caucasian women and 35 Asian women. UVB exposure (polysulphone film badges) and dietary vitamin D intakes (food diaries) were also estimated.
Results
Caucasian women had lower 25(OH)D (p < 0.001) at 57° N compared to 51° N. Median (interquartile range) in nanomoles per litre for summer (June–August) at 57° N was 43.0 (20.9) and at 51° N was 62.5 (26.6) and for winter (December–February) at 57° N was 28.3 (18.9) and at 51° N was 39.9 (24.0). For Asian women at 51° N, median 25(OH)D was 24.0 (15.8) nmol/L in summer and 16.9 (15.9) nmol/L in winter. Median dietary vitamin D intakes were 80–100 IU for Caucasians and 50–65 IU for the Asian women. Sunlight was the main contributor to 25(OH)D with spring and summer providing >80% total annual intake.
Conclusions
These longitudinal data show significant regional and ethnic differences in UVB exposure and vitamin D status for postmenopausal women at northerly latitudes. The numbers of women who are vitamin D deficient is a major concern and public health problem.
Original languageEnglish
Pages (from-to)2461-2472
Number of pages12
JournalOsteoporosis International
Volume22
Issue number9
Early online date18 Nov 2010
DOIs
Publication statusPublished - Sep 2011

Keywords

  • dietary vitamin D
  • longitudinal study
  • postmenopausal women
  • regional vitamin D status

Fingerprint Dive into the research topics of 'Sunlight and dietary contributions to the seasonal vitamin D status of cohorts of healthy postmenopausal women living at northerly latitudes: a major cause for concern?'. Together they form a unique fingerprint.

  • Cite this