Osteoporosis International

, Volume 22, Issue 9, pp 2461–2472

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?

Authors

    • University of Aberdeen
    • Musculoskeletal Research, Health Sciences BuildingUniversity of Aberdeen
  • A. Mavroeidi
    • University of Aberdeen
  • W. D. Fraser
    • Department of Musculoskeletal BiologyUniversity of Liverpool
  • A. L. Darling
    • Nutritional Sciences Division, Faculty of Health and Medical SciencesUniversity of Surrey
  • A. J. Black
    • University of Aberdeen
  • L. Aucott
    • University of Aberdeen
  • F. O’Neill
    • University of Aberdeen
  • K. Hart
    • Nutritional Sciences Division, Faculty of Health and Medical SciencesUniversity of Surrey
  • J. L. Berry
    • Vitamin D Research Group, Department of MedicineManchester Royal Infirmary
  • S. A. Lanham-New
    • Nutritional Sciences Division, Faculty of Health and Medical SciencesUniversity of Surrey
  • D. M. Reid
    • University of Aberdeen
Original Article

DOI: 10.1007/s00198-010-1467-z

Cite this article as:
Macdonald, H.M., Mavroeidi, A., Fraser, W.D. et al. Osteoporos Int (2011) 22: 2461. doi:10.1007/s00198-010-1467-z

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.

Keywords

Dietary vitamin DLongitudinal studyPostmenopausal womenRegional vitamin D statusSeasonal 25-hydroxyvitamin DSunlight exposure

Supplementary material

198_2010_1467_MOESM1_ESM.doc (26 kb)
ESM 1(DOC 26 kb)

Copyright information

© International Osteoporosis Foundation and National Osteoporosis Foundation 2010