The role of sunlight exposure in determining the vitamin D status of the UK white Caucasian adult population.

Br J Dermatol ():no (2010)
profile A R Webb, profile R Kift, profile M T Durkin, profile S J O'Brien, profile A Vail, profile J L Berry and profile L E Rhodes
School of Earth Atmospheric and Environmental Sciences, University of Manchester, Manchester, UK.

ABSTRACT Background: Vitamin D is necessary for bone health and potentially protective against a range of malignancies. Opinions are divided on whether the proposed optimal circulating 25(OH)D level (>/= 32 ng/mL) is an appropriate and feasible target at population level.

Objective: We examined whether personal sunlight exposure levels can provide vitamin D sufficient (>/= 20 ng/mL) and optimal status in the UK public.

Methods: This prospective cohort study measured circulating 25(OH)D monthly for 12 months in 125 white Caucasians aged 20-60 years in Greater Manchester. Dietary vitamin D and personal ultraviolet (UV) exposure were assessed over 1-2 weeks in each season. The primary analysis determined the post-summer peak 25(OH)D required to maintain sufficiency in winter-time.

Results: Dietary vitamin D remained low in all seasons (median 3.27 mug/day, range 2.76-4.15) while personal UV exposure levels were high in spring and summer, low in autumn and negligible in winter. Mean 25(OH)D levels were maximal in
September (28.4 ng/mL; 28% optimal, zero deficient (< 5 ng/mL)), and minimal in
February (18.3 ng/mL; 7% optimal, 5% deficient).
A February 25(OH)D level of 20ng/mL was achieved following an average late summer level of 30.4 (25.6 to 35.2) and 34.9 (27.9 to 41.9) ng/mL in women and men, respectively, with 62% variance explained by gender and September levels.

Conclusions: Late summer 25(OH)D levels approximating the optimal range are required to retain sufficiency throughout the UK winter. Currently the majority of the population fails to reach this post-summer level and becomes vitamin D insufficient during the winter. DOI: 10.1111/j.1365-2133.2010.09975.x * PMID: 20716215
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See also Vitamin D Life

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