Factors associated with the serum 25-hydroxyvitamin D levels in adults

Hypovitaminosis D has a significant negative impact on general health. Although some factors associated with hypovitaminosis D have been previously reported, they have seldom been analyzed simultaneously in community-based research. This study aims to investigate some potential factors associated with serum 25 (OH)D level, representing a vitamin concentration.

A cross-sectional study recruiting 4,457 adults, aged over 18 years, was conducted between August 2019 and December 2023. Sociodemographic data were obtained through structured questionnaires, while anthropometric measurements, hemogram results, and biochemical markers were collected from medical records and physical examination findings. A self-reported depression rating score; health beliefs; and health-related quality of life (HRQoL) factors were assessed with questionnaires. Univariate and multivariate analyses were performed.

The mean serum 25(OH)D level was 29.22 ± 10.45 ng/mL. Multivariate linear regression analysis revealed that serum 25(OH)D levels were positively associated with age (β = 0.258, p < 0.001), male sex (β = 0.164, p < 0.001), high school education level (β = 0.118, p < 0.001), smoking exposure (β = 0.044, p = 0.011), alcohol consumption (β = 0.150, p < 0.001), hemoglobin concentration (β = 0.062, p = 0.001), calcium level (β = 0.047, p = 0.005), and the mental component score of health-related quality of life (HRQoL) (β = 0.086, p < 0.001). Conversely, serum 25(OH)D levels were negatively associated with coffee consumption (β = - 0.045, p = 0.002), estimated glomerular filtration rate (β = - 0.105, p < 0.001), blood levels of intact parathyroid hormone (β = - 0.184, p < 0.001), phosphorus (β = - 0.033, p = 0.040), and triglycerides (β = - 0.060, p < 0.001). The overall model explained 29.6% of the variance in serum 25(OH)D levels (R² = 0.296). There were close correlations between sociodemographic factors, anthropometric variables, hemograms, biochemical data, self-reported depression rating scores, health beliefs, and HRQoL factors.

This study identified several key variables associated with serum 25(OH)D levels in adults. These findings provide important targets for designing health education programs aimed at reducing the prevalence of vitamin D insufficiency. Future community-based research should consider incorporating additional determinants of vitamin D status, including quantified sunlight exposure, dietary intake of vitamin D-rich foods, and supplementation patterns. Accounting for these broader lifestyle and environmental factors may enable subsequent studies to generate more robust insights into the multifactorial nature of vitamin D regulation and inform more effective public health strategies.