Prevalence and predictors of vitamin D insufficiency in children: a Great Britain population based study.

OBJECTIVES

To evaluate the prevalence and predictors of vitamin D insufficiency (VDI) in children in Great Britain.

DESIGN

A nationally representative cross-sectional study survey of children (1102) aged 4-18 years (999 white, 570 male) living in private households (January 1997-1998). Interventions provided information about dietary habits, physical activity, socio-demographics, and blood sample. Outcome measures were vitamin D insufficiency (<50 nmol/L).

RESULTS

Vitamin D levels (mean = 62.1 nmol/L, 95%CI 60.4-63.7) were insufficient in 35%, and decreased with age in both sexes (p<0.001). Young People living between 53-59 degrees latitude had lower levels (compared with 50-53 degrees, p = 0.045). Dietary intake and gender had no effect on vitamin D status. A logistic regression model showed increased risk of VDI in the following: adolescents (14-18 years old), odds ratio (OR) = 3.6 (95%CI 1.8-7.2) compared with younger children (4-8 years); non white children (OR = 37 [95%CI 15-90]); blood levels taken December-May (OR = 6.5 [95%CI 4.3-10.1]); on income support (OR = 2.2 [95%CI 1.3-3.9]); not taking vitamin D supplementation (OR = 3.7 [95%CI 1.4-9.8]); being overweight (OR 1.6 [95%CI 1.0-2.5]); <1/2 hour outdoor exercise/day/week (OR = 1.5 [95%CI 1.0-2.3]); watched >2.5 hours of TV/day/week (OR = 1.6[95%CI 1.0-2.4]).

CONCLUSION

We confirm a previously under-recognised risk of VDI in adolescents. The marked higher risk for VDI in non-white children suggests they should be targeted in any preventative strategies. The association of higher risk of VDI among children who exercised less outdoors, watched more TV and were overweight highlights potentially modifiable risk factors. Clearer guidelines and an increased awareness especially in adolescents are needed, as there are no recommendations for vitamin D supplementation in older children.