VDR BsmI polymorphism and obesity in vitamin D deficiency among undergraduate students: a cross-sectional study.

BACKGROUND: Undergraduate students constitute a relevant population for investigating genetic and body weight-related factors associated with vitamin D deficiency. This study aimed to assess the associations of the VDR BsmI single nucleotide polymorphism (SNP) and body weight status, including obesity, with vitamin D deficiency in undergraduate students. METHODS AND RESULTS: This cross-sectional study included biochemical and genetic assessment conducted between April and May 2023. A total of 189 students were evaluated after excluding individuals who had received vitamin D supplementation within the six months preceding data collection. SNP genotyping was performed by qPCR using TaqMan probes, vitamin D levels were measured by chemiluminescent immunoassay, and body weight classification was determined according to World Health Organization (WHO) criteria. Vitamin D deficiency was observed in 34.9% of the participants. Individuals with vitamin D deficiency had significantly higher body weight, waist and hip circumference, and body fat percentage than those with sufficient vitamin D levels. The distributions of the BsmI genotypes and alleles differed significantly between the vitamin D groups. Multivariate logistic regression showed that obesity (OR = 4.260; 95% CI: 1.656-10.959) and the recessive genetic model (OR = 4.361; 95% CI: 1.200-15.846) were independently associated with vitamin D deficiency. CONCLUSIONS: Obesity and the VDR BsmI recessive genetic model were independently associated with higher odds of vitamin D deficiency in undergraduate students. These findings highlight the concurrent relevance of genetic and body weight-related factors to vitamin D status and support further research to inform preventive strategies in this population.