Associations between Serum 25-Hydroxyvitamin D Levels and Metabolic Syndrome in Male Shift Workers

Abstract

Abstract Objective: We investigated the association between serum 25-hydroxyvitamin D (25(OH)D) levels and metabolic syndrome (MetS) in male shift workers vulnerable to serum 25(OH)D deficiency. Materials and methods: Laboratory measurements and self-questionnaire survey were conducted on 985 daytime and 755 shift workers. Shift workers comprised two-shift (n = 38) and three-shift (n = 717). Variables between daytime and shift workers were compared, the correlation between these variables and serum 25(OH)D levels and differences of variables according to quartiles of serum 25(OH)D levels were analyzed. Odds ratios (OR) of MetS and metabolic components depending on serum 25(OH)D levels were determined using multiple logistic regression analysis. Results: The prevalence of Met S in daytime and shift workers was 24.7% and 23.8%, respectively. In daytime workers, mean serum 25(OH)D level was lower and age, the number of alcohol drinker, worker who lack exercise and sleep, married worker was higher than shift workers with significance. After correction of confounding factors including lifestyle, sociodemographic factors and seasonal variation, MetS (OR = 1.580, 95% CI = 1.004-2.488, P = 0.048) and waist circumference (OR = 1.915, 95% CI = 1.217-3.013, P = 0.005) were statistically significant in daytime workers, but not in shift workers. Both groups with serum 25 (OH) D deficiency showed hypertriglyceridemia regardless of MetS. Conclusions: Associations between serum 25(OH)D levels and MetS in shift workers could be affected by confounding factors and working condition. Serum 25(OH) D deficiency is a risk factor of hypertriglyceridemia in male workers.