Abstract
Little research has assessed serum 25-hydroxyvitamin D (25(OH)D) concentration and its predictors in western dwelling South Asians in a relatively large sample size. This observational, cross-sectional analysis assessed baseline prevalence of 25(OH)D deficiency in UK dwelling South Asians (aged 40-69 years, 2006-2010) from the UK Biobank cohort. Serum 25(OH)D measurements were undertaken using the DiaSorin Liaison XL assay. Of n 6433 South Asians with a 25(OH)D measurement, using commonly used cut-off thresholds, 55% (n 3538) had 25(OH)D <25 nmol/L (severe deficiency) and 92% (n 5918) had 25(OH)D <50 nmol/L (insufficiency). Twenty per cent (n 1287) had 25(OH)D concentration <15 nmol/L (very severe deficiency). When n 824 participants with undetectable (<10 nmol/L) 25(OH)D measurements were included (total n 7257), 29% (n 2105) had 25(OH)D <15 nmol/L, 60% (n 4354) had 25(OH)D <25 nmol/L and 93% (n 6749) had 25(OH)D < 50 nmol/L. Logistic regression predictors of 25(OH)D <25 nmol/L included the following characteristics: being male; Pakistani; higher body mass index; 40-59 years old; never consuming oily fish; summer sun exposure < 5 hours per day, not using a vitamin D containing supplement, measurement in winter or spring and vegetarianism. In terms of region, median 25(OH)D concentration was 19-20 nmol/L in Scotland, Northern England, the Midlands and Wales. Across Southern England and London it was slightly higher at 24-25 nmol/L. Our analyses suggest the need for increased awareness of vitamin D deficiency in South Asians as well as urgent public health interventions to prevent and treat vitamin D deficiency in this group.