title: Environmental and genetic determinants of vitamin D status among older adults in London, UK.
abstract: Despite the high prevalence of vitamin D deficiency among older adults in the UK, studies investigating the determinants of vitamin D status in this group are lacking. We conducted a cross-sectional study in 222 older adults living in sheltered accommodation in London, UK, who were screened for participation in a clinical trial of vitamin D supplementation for the prevention of acute respiratory infection. Details of potential demographic and lifestyle determinants of vitamin D status were collected by questionnaire and blood samples were taken for analysis of serum 25-hydroxyvitamin D (25[OH]D) concentration and DNA extraction. Fifteen single nucleotide polymorphisms (SNP) in 6 genes (DBP, DHCR7, CYP2R1, CYP27B1, CYP24A1, VDR) previously reported to associate with circulating 25(OH)D concentration were typed using Taqman allelic discrimination assays. Linear regression was used to identify environmental and genetic factors independently associated with serum 25(OH)D concentration. Mean serum 25(OH)D concentration was 42.7nmol/L (SD 22.0); 144/222 (64.9%) participants had serum 25(OH)D concentrations <50nmol/L. The following factors were independently associated with lower serum 25(OH)D concentration: non-white ethnicity (-8.6nmol/L, 95% CI -14.9 to -2.3, P=0.008); lack of vitamin D supplement consumption (-17.1nmol/L, 95% CI -23.3 to -10.9, P<0.001) vs. taking a daily supplement; sampling in Q1/January-March (-12.2nmol/L, 95% CI -21.5 to -2.9, P=0.01), and sampling in Q4/October-December (-10.3nmol/L, 95% CI -20.2 to -0.4, P=0.04) vs. sampling in Q3/July-September. None of the 15 SNP investigated independently associated with serum 25(OH)D concentration after correcting for multiple comparisons. In conclusion, vitamin D deficiency was highly prevalent among the older adults in this study; non-White ethnicity, lack of vitamin D supplement consumption and sampling in winter and spring independently associated with lower vitamin D status.
authors.affiliation: Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AB, UK. Electronic address: d.a.jolliffe@qmul.ac.uk.
authors.forename: David A
authors.initials: DA
authors.lastname: Jolliffe
authors.affiliation: London School of Hygiene and Tropical Medicine, 15-17 Tavistock Place, London WC1H 9SH, UK.
authors.forename: Yasmeen
authors.initials: Y
authors.lastname: Hanifa
authors.affiliation: Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AB, UK.
authors.forename: Karolina D
authors.initials: KD
authors.lastname: Witt
authors.affiliation: Homerton University Hospital, Homerton Row, London E9 6SR, UK.
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Venton
authors.affiliation: Homerton University Hospital, Homerton Row, London E9 6SR, UK.
authors.forename: Marion
authors.initials: M
authors.lastname: Rowe
authors.affiliation: Homerton University Hospital, Homerton Row, London E9 6SR, UK.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Timms
authors.affiliation: School of Population Health, University of South Australia, Adelaide, Australia.
authors.forename: Elina
authors.initials: E
authors.lastname: Hyppönen
authors.affiliation: Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AB, UK.
authors.forename: Robert T
authors.initials: RT
authors.lastname: Walton
authors.affiliation: Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AB, UK.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Griffiths
authors.affiliation: Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AB, UK. Electronic address: a.martineau@qmul.ac.uk.
authors.forename: Adrian R
authors.initials: AR
authors.lastname: Martineau
mesh_terms: D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase / Q000235:genetics; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D053493:Cholestanetriol 26-Monooxygenase / Q000235:genetics; D002986:Clinical Trials as Topic; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D000072467:Cytochrome P450 Family 2 / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D004032:Diet; D019587:Dietary Supplements; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008131:London; D008297:Male; D008875:Middle Aged; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000235:genetics; D020641:Polymorphism, Single Nucleotide; D018167:Receptors, Calcitriol / Q000235:genetics; D012621:Seasons; D014157:Transcription Factors / Q000235:genetics; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood / Q000235:genetics* / Q000627:therapeutic use; D014808:Vitamin D Deficiency / Q000097:blood* / Q000453:epidemiology / Q000235:genetics*; D065668:Vitamin D3 24-Hydroxylase / Q000235:genetics
chemical_list: C063898:DBP protein, human; D004268:DNA-Binding Proteins; D018167:Receptors, Calcitriol; D014157:Transcription Factors; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D000072467:Cytochrome P450 Family 2; C506833:CYP2R1 protein, human; D053493:Cholestanetriol 26-Monooxygenase; C585549:CYP24A1 protein, human; D065668:Vitamin D3 24-Hydroxylase; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase; C000600378:CYP27B1 protein, human; D044925:Oxidoreductases Acting on CH-CH Group Donors; C019995:7-dehydrocholesterol reductase
keywords: Ageing; Diet; Polymorphism; Season; Single nucleotide; Vitamin D