title: Vitamin D status: multifactorial contribution of environment, genes and other factors in healthy Australian adults across a latitude gradient.
abstract: Vitamin D deficiency is common and implicated in risk of several human diseases. Evidence on the relative quantitative contribution of environmental, genetic and phenotypic factors to vitamin D status (assessed by the serum concentration of 25-hydroxyvitamin D, 25(OH)D) in free-living populations is sparse. We conducted a cross-sectional study of 494 Caucasian adults aged 18-61years, randomly selected from the Australian Electoral Roll according to groups defined by age, sex and region (spanning 27°-43°South). Data collected included personal characteristics, sun exposure behaviour, biomarkers of skin type and past sun exposure, serum 25(OH)D concentration and candidate single nucleotide polymorphisms. Ambient ultraviolet radiation (UVR) levels in the month six weeks before blood sampling best predicted vitamin D status. Serum 25(OH)D concentration increased by 10nmol/L as reported time in the sun doubled. Overall, 54% of the variation in serum 25(OH)D concentration could be accounted for: 36% of the variation was explained by sun exposure-related factors; 14% by genetic factors (including epistasis) and 3.5% by direct measures of skin phenotype. Novel findings from this study are demonstration of gene epistasis, and quantification of the relative contribution of a wide range of environmental, constitutional and genetic factors to vitamin D status. Ambient UVR levels and time in the sun were of prime importance but it is nonetheless important to include the contribution of genetic factors when considering sun exposure effects. This article is part of a Special Issue entitled 'Vitamin D Workshop'.
authors: National Centre for Epidemiology and Population Health, The Australian National University, Canberra 0200, Australia. robyn.lucas@anu.edu.au
authors: Robyn M
authors: RM
authors: Lucas
authors: Anne-Louise
authors: AL
authors: Ponsonby
authors: Keith
authors: K
authors: Dear
authors: Patricia C
authors: PC
authors: Valery
authors: Bruce
authors: B
authors: Taylor
authors: Ingrid
authors: I
authors: van der Mei
authors: Anthony J
authors: AJ
authors: McMichael
authors: Michael P
authors: MP
authors: Pender
authors: Caron
authors: C
authors: Chapman
authors: Alan
authors: A
authors: Coulthard
authors: Trevor J
authors: TJ
authors: Kilpatrick
authors: Jim
authors: J
authors: Stankovich
authors: David
authors: D
authors: Williams
authors: Terence
authors: T
authors: Dwyer
mesh_terms: D000293:Adolescent; D000328:Adult; D001315:Australia; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D004777:Environment; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D018167:Receptors, Calcitriol / Q000235:genetics*; D012880:Skin Pigmentation / Q000235:genetics; D013472:Sunlight; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood / Q000235:genetics; D055815:Young Adult
chemical_list: D018167:Receptors, Calcitriol; C579457:VDR protein, human; D014807:Vitamin D; C104450:25-hydroxyvitamin D