Vitamin D Status in Polish Military Personnel: Associations with Supplementation, Seasonality, and the GC rs2282679 Polymorphism

Introduction/Aim of the study: Vitamin D participates in the regulation of calcium and phosphate metabolism and exerts pleiotropic effects that encompass numerous physiological processes. The study aimed to assess vitamin D status in Polish military personnel and to analyze its association with supplementation, the frequency of consumption of selected products that are sources of vitamin D, demographic and anthropometric factors, seasonality, and the GC rs2282679 polymorphism. Methods: The study included 331 soldiers aged 21–65 years, 88.2% of whom were men. 25(OH)D levels were determined by electrochemiluminescence, the frequency of product consumption was assessed using the FFQ questionnaire, and GC rs2282679 genotyping was performed by real-time PCR using TaqMan probes. Suboptimal vitamin D status was defined as a concentration of 25(OH)D < 30 ng/mL. Results: The concentration of 25(OH)D < 30 ng/mL was determined in 50.2% of the subjects. Multivariable analysis showed the following independent factors associated with the suboptimal status of vitamin D: blood collection in the spring, less frequent supplementation and the GG genotype of the GC rs2282679 polymorphism. Age, sex and BMI showed no independent association with this endpoint. The frequency of the consumption of most analyzed products was not significantly associated with 25(OH)D levels. The concentration of 25(OH)D showed a negative correlation with PTH and homocysteine and a weak positive correlation with inorganic phosphorus. The analysis of the classification tree indicated that the GG genotype identified the subgroup with the lowest 25(OH)D concentration. Conclusions: The suboptimal vitamin D status occurred in about half of the examined soldiers. The results indicated the importance of regular supplementation, seasonality and the GC rs2282679 polymorphism in the identification of individuals particularly susceptible to suboptimal vitamin D status.