Recommended summer sunlight exposure amounts fail to produce sufficient vitamin D status in UK adults of South Asian origin

The cutaneous synthesis of vitamin D is dependent on UVB from sunlight, but melanin reduces the penetration of UVB and thus contributes to vitamin D insufficiency in individuals with darker skin. The national guidance provided on amounts of sunlight exposure in the United Kingdom is for the light-sk...

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Bibliographic Details
Published in:The American journal of clinical nutrition 2011-11, Vol.94 (5), p.1219
Main Authors: Farrar, Mark D, Kift, Richard, Felton, Sarah J, Berry, Jacqueline L, Durkin, Marie T, Allan, Donald, Vail, Andy, Webb, Ann R, Rhodes, Lesley E
Format: Article
Language:English
Subjects:
Adult
Asia - ethnology
Cohort Studies
Female
Human exposure
Humans
Male
Middle Aged
Parathyroid Hormone - blood
Prospective Studies
Seasons
Skin
Summer
Sunlight
Ultraviolet radiation
United Kingdom
Vitamin D
Vitamin D - analogs & derivatives
Vitamin D - biosynthesis
Vitamin D - blood
Vitamin deficiency
Young Adult
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Summary:The cutaneous synthesis of vitamin D is dependent on UVB from sunlight, but melanin reduces the penetration of UVB and thus contributes to vitamin D insufficiency in individuals with darker skin. The national guidance provided on amounts of sunlight exposure in the United Kingdom is for the light-skinned population, and in the absence of dedicated information, darker-skinned people may attempt to follow this guidance. We determined the relative effect of a simulation of UK recommendations of summer sunlight exposure on the vitamin D status of individuals of South Asian ethnicity compared with that of whites. In a prospective cohort study, simulated summer sunlight exposures were provided under rigorous dosimetric conditions to 15 adults (aged 20-60 y) of South Asian ethnicity, and serum 25-hydroxyvitamin D [25(OH)D] was measured weekly. Dietary vitamin D intake was estimated. Outcomes were compared with those of 109 whites (aged 20-60 y) treated with the identical UV-radiation exposure protocol. At baseline (winter trough), all South Asians were vitamin D-insufficient [25(OH)D concentrations
ISSN:0002-9165
1938-3207
DOI:10.3945/ajcn.111.019976