Obesity Abstracts

Background: Several studies have investigated the association between vitamin D receptor (VDR) variants and the risk of cardiometabolic complications. The pleiotropic action of VDR in extra-skeletal tissues gives physiologic plausibility to the associations between VDR variants and metabolic health, particularly in obese individuals. Whilst multiple conflicting findings have been reported, clinical data has shown that despite an increase in physical activity and nurturing healthier dietary choices, there are individuals who do not benefit from lifestyle changes. This study aims to replicate the association between common VDR variants and obesity risk in a well-characterised Maltese cohort stratified into metabolically healthy and unhealthy obese phenotypes; a hypothesis that has never been investigated in the Maltese population.

Methods: A cross-sectional case-control study involving 480 working age Maltese adults was conducted. The cohort was stratified into four different body composition phenotypes based on BMI and metabolic syndrome components. Four VDR polymorphisms [FokI (rs2228570), BsmI (rs1544410), ApaI (rs7975232) and TaqI (rs731236)] were genotyped by PCR-RFLP, and the association with metabolic health phenotypes was investigated.

Results: The VDR TaqI C/C genotype was associated with higher odds of obesity, independent of metabolic health status. A higher frequency of the BsmI G/A and TaqI T/C genotypes was observed in the MHO (metabolically healthy obese) subgroup when compared to the MUHO (metabolically unhealthy obese) subgroup. VDR haplotype block 2 was associated with a significantly higher odds of MHO.

Conclusions: Our results suggest that in the high prevalence Maltese population, VDR polymorphisms are associated with obesity and metabolic health status. Future studies should further investigate the overall effect of multiple variants associated with obesity phenotypes and relate genotypes with the longitudinal progression of obesity to assess the dynamic nature of metabolic health.