Prevalence and correlates of vitamin D deficiency in primary school children of South Asian, White European, Black African and Caribbean and White European origin: a cross-sectional survey (2004-2007) in London, Birmingham and Leicester.

Vitamin D deficiency is common in the UK, especially in certain ethnic minority populations. There is limited information on childhood vitamin D status in the UK, or factors associated with vitamin D deficiency. Using a cross-sectional study of 4650 children of South Asian, Black African and Caribbean and White European origins (9-10 years old) surveyed between 2004 and 2007, we investigated measurements of circulating 25(OH)D concentrations (a measure of vitamin D status) and anthropometric measurements. Overall, 68 % of children had 25(OH)D concentrations ≤ 50 nmol/L and were either insufficient (25-50 nmol/L) (45 %) or deficient (< 25 nmol/L) (23 %). Mean 25(OH)D concentrations were lowest in South Asian (especially Bangladeshi) children, intermediate in Black African and Caribbean and highest in White European children. Mean values were ≤ 50 nmol/L for all children during the winter months and ≤ 50 nmol/L throughout the year for South Asian, Black African and Caribbean children. In analyses adjusted for season, age, sex, ethnicity, socio-economic status and fat mass index, girls had a higher risk of being vitamin D deficient or insufficient (OR 1·49, 95 % CI 1·32, 1·68) compared with boys. South Asian children (OR 25·49, 95 % CI 19·95, 32·57) and Black African and Caribbean children (OR 10·31, 95 % CI 10·31, 17·52) had the highest risks of being deficient or insufficient compared with White European children. Childhood vitamin D deficiency was common in this study population. In the UK, targeted and novel interventions are needed to increase 25(OH)D concentrations, particularly South Asian and Black African and Caribbean children and reduce the health risks associated with low vitamin D status.