Vitamin D Receptor Gene Variation, Dietary Intake and Bone Mineral Density in Obese Women: A Cross Sectional Study

Osteoporosis and fragility fractures have been regarded as important public health concerns. We investigated their possible association with vitamin D receptor (VDR) FOK1 polymorphisms (rs10735810) and dietary parameters such as calcium and vitamin D intake. A total of 264 Iranian obese women (BMI>30 kg/m²) were categorized based on the FOK1 genotype and divided into two groups: group one with the FF genotype (n=184) and the f allele carrier group with the Ff or ff genotype (n=80). The body composition, dietary intake and bone mineral density were assessed for all cases. The frequency of the F and f alleles for FOK1 in the study were 71.5% and 28.5%, respectively. Women with the f allele had a higher BMI (p=0.05), as well as parathyroid hormone (PTH) and tumor necrosis factor alpha (TNF-α) concentration (p=0.05, p=0.01, respectively). Participants with calcium intakes of more than 1,000 mg/d and the ff genotype had a higher L2_L4 Z-score. Moreover, women with vitamin D intakes of less than 600 IU/d and the ff genotype had a higher total T-score and total Z-score. Although women whose dietary intake of vitamin D was higher than the recommended dietary allowance (RDA>600 IU/d) and had the FF genotype had a higher total T-score and total Z-score, as well. Our findings suggest that interactions between FOK1 polymorphisms in Iranian obese women and dietary intake of calcium and vitamin D may play a decisive role in bone mineral density and osteoporosis among these women.