Case study

Vitamin D insufficiency in children

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Author: Michael Absoud, University of Birmingham

Date: 15 September 2011

Type of case study: Research

About the research

This study set out to evaluate the prevalence and predictors of vitamin D insufficiency (VDI) in children In Great Britain. Vitamin D functions as a hormone and its importance in the immunomodulatory effects on disease is being increasingly recognised.

The results 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.

Additionally, children whose families received income support were more likely to have VDI. For this reason, government initiatives to tackle social inequalities may have an impact on vitamin D status.

The association of higher risk of VDI among children who exercised less outdoors, watched more TV and were overweight highlights potentially modifiable risk factors. This implies that initiatives to encourage more outdoor activities, particularly in the summer months, may have an impact on vitamin D status. This also suggests that guidelines encouraging safe sunlight exposure may need to be revised.

In conclusion, the authors suggest that clearer guidelines and an increased awareness especially in adolescents are needed, as there are no recommendations for vitamin D supplementation in older children in the UK.

About the data

The research used data from the National Diet and Nutrition Survey, a nationally representative cross-sectional study survey of children aged 4–18 years living in private households (January 1997–1998). Interventions provided information about dietary habits, physical activity, socio-demographics, and blood sample.

Variables used as predictors:

  • age, gender and ethnicity
  • whether on income Support
  • region of residence
  • month blood was taken
  • time spent per week in sports involving outdoor exercise or play
  • time spent a day per week watching TV
  • vitamin D dietary intake and supplemental vitamin D intake
  • body mass index (BMI [kg/m2])

To classify overweight and obesity in young people 2–18 years of age, cut-offs described by Cole et al (on behalf of the International Obesity Task Force) were used.


Statistical analysis of the data included descriptive statistics (summarising data), univariate regression and binary loglinear regression(methods to create a model to predict an outcome based on a set of variables). In the different models, Vitamin D was used as a continuous variable, and as a binary outcome for insufficiency (,50 nmol/L). The researchers also used chi squared and t-tests to investigate significance of proposed predictors for VDI and vitamin D status respectively.

Publications and outputs

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