Obesity leads to vitamin D deficiency

Obesity can lead to a lack of vitamin D circulating in the body, according to a study led by the UCL Institute of Child Health (ICH). Efforts to tackle obesity should thus also help to reduce levels of vitamin D deficiency in the population, says the lead investigator of the study, Elina Hypponen. While previous studies have linked vitamin D deficiency with obesity, the ICH-led paper, published in the journal PLOS Medicine , sought to establish the direction of causality, i.e. whether a lack of vitamin D triggers a weight gain, or whether obesity leads to the deficiency. This study used genetic markers derived from an analysis of 21 adult cohort groups (up to 42,000 participants) to explore the link between body mass index (BMI) and genes associated with the synthesis and metabolism of vitamin D. Associations between vitamin D and BMI were further confirmed using data from another genetic consortium with over 123,000 participants. Researchers found that a 10 per cent rise in BMI was linked to a four per cent drop in concentrations of vitamin D in the body. Overall, the findings suggest that a higher BMI leads to lower levels of available vitamin D, while the effect of a lack of vitamin D on BMI appears to be very small. The association between obesity and vitamin D status found here was consistent between genders, being apparent both in men and in women, and in younger and older age groups.