Determinants of circulating 25-hydroxyvitamin D concentration and its association with musculoskeletal health in midlife: Findings from the Hertfordshire Cohort Study.
Bevilacqua G., Laskou F., Clynes MA., Jameson KA., Boucher BJ., Noonan K., Cooper C., Dennison EM.
Introduction: Several studies have reported the importance of vitamin D status to musculoskeletal health in populations of older adults. Here we report relationships between circulating serum 25(OH)D and musculoskeletal health in a community cohort of UK adults in midlife and investigate whether environmental (dietary intake, use of supplements) and/or genetic factors (4 SNPs previously related to vitamin D status) play more significant roles in determining vitamin D status in this population. Methods: Participants were recruited from the Hertfordshire Cohort Study, an established longitudinal cohort study of community dwelling adults and were seen at baseline and follow up 9-12 years later. Lumbar spine and total femur BMD were measured at baseline using a Hologic QDR 4500 instrument. Osteoarthritis (OA) was defined by radiographs of the knees graded according to Kellgren & Lawrence at both time points. Serum 25(OH)D concentrations were measured using a DiaSorin Liaison chemiluminescent assay. Genotyping of 4 SNPs previously associated with 25(OH)D values were assessed: (rs12785878 (DHCR7), rs10741657 (CYP2R1) and rs6013897 (CYP24A1)) and a fourth SNP (rs4588), described as "a near-perfect proxy (i.e. substitute) for rs2282679 on the GC gene". Results: 820 subjects (397 men, 423 women) participated at baseline, and 339 of these 820 subjects (164 men; 175 women) participated in a follow up study of OA progression. The median (IQR) age of participants at baseline was 64.0 (61.8-66.5) and 65.5 (63.3-67.6) for men and women respectively. Median circulating levels of 25(OH)D were 44.6 (35.0-63.0) nmol/L and 41.3 (29.8-53.5) nmol/L in men and women respectively. Circulating 25(OH)D was strongly associated with season of blood testing (p