Obesity is a causal factor in vitamin D deficiency, but vitamin D deficiency does not lead to any significant weight gain, according to a multicenter, genetic study published online February 5 in PLoS Medicine.
“While many health messages have focused on a lack of sun exposure or excessive use of suncreams, we should not forget that vitamin D deficiency is also caused by obesity,” lead author Elina Hypponen, PhD, from the Institute of Child Health at University College London, United Kingdom, said in a news release.
“Our study highlights the importance of monitoring and treating vitamin D deficiency in people who are overweight or obese, in order to alleviate adverse health effects caused by a lack of vitamin D.”
To evaluate the association between body mass index (BMI) and genes linked to vitamin D synthesis and metabolism, the researchers used genetic markers identified by analyzing 21 cohort groups that enrolled up to 42,024 participants for the D-CarDia Collaboration. The researchers confirmed associations between vitamin D and BMI using data from the Genetic Investigation of Anthropometric Traits (GIANT) consortium, which enrolled up to 123,865 participants.
“The researchers used bidirectional Mendelian randomization to examine the direction and causality of the relationship between BMI and 25(OH)D,” Valeria Hirschler, MD, researcher in pediatrics, nutrition, and diabetes at the University of Buenos Aires in Argentina, told Medscape Medical News when asked for independent comment. “With this method, causality is inferred from associations between genetic variants that mimic the influence of a modifiable environmental exposure and the outcome of interest.”
Across age and sex subgroups, every 10% increase in BMI was associated with a 4.2% reduction in 25(OH)D concentrations, suggesting that higher BMI results in lower vitamin D levels, with a negligible effect of vitamin D deficiency on BMI.
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Source: by Laurie Barclay, MD on Feb 08, 2013 at http://www.medscape.com/viewarticle/779064?nlid=28243_1301&src=wnl_edit_dail