Vitamin D receptor gene polymorphisms as a risk factor for obesity in Saudi men

Background The prevalence of obesity and vitamin D deficiency in Saudi Arabia has increased recently. Decreased physical activity might play a role in obesity. Previous studies showed an association between low vitamin D level and its receptor polymorphism with obesity development. Objective To determine association of low vitamin D level and its receptor polymorphism with obesity in Saudi men. Methods This case control study was carried out from March 2016 through March 2017. Three hundred Saudi male students (from applied medical sciences in Taif University, Taif, Saudi Arabia) were classified according to BMI into lean, overweight and obese groups. For each individual, blood glucose, cholesterol, HDL-C, LDL-C, insulin and 25-(OH) vitamin D were measured. In addition, Apal, BsmI and TaqI genotypes were performed for each individual from March 2016 through March 2017, through computer-based search of the following databases: PubMed, Web of Science (Thomson ReutersTM). The references of the original literature and the related articles were also searched, for potential complementary studies. Data were analyzed by SPSS version 16, using Spearman's rho and ANOVA tests. Results There was significant negative association between 25-(OH) vitamin D level and obesity (p<0.01). Genotyping study showed that both bb of BsmI and tt of TaqI genotypes were higher in the obese group compared with lean group (p<0.05). Moreover, bb genotype has higher BMI and HOMA-IR than both BB and Bb; and tt genotype also has higher BMI and HOMA-IR than TT and Tt genotypes (p<0.05). Conclusion Low vitamin D level and VDR BsmI and Taq1 genotypes may be a risk factor of obesity.