Interaction of Vitamin D Receptor Gene FokI Variants and Omega-3 Fatty Acids on Perceived Stress Score and Serum Cortisol Levels in Nurses: A Cross-Sectional Study

There is a high prevalence of perceived stress among nurses. Recent studies have shown that omega-3 fatty acids and genetic variants contribute to perceived stress. This study aimed to examine interactions between vitamin D receptor (VDR) gene FokI polymorphism and omega-3 fatty acids on perceived stress score and serum cortisol levels in nurses. Methods: A total of 268 Iranian nurses (248 women; 20 men) participated in this cross-sectional study. Omega-3 fatty acids and perceived stress score of participants were evaluated using a 3-day food record and the Perceived Stress Scale (PSS)-10, respectively. Serum cortisol concentrations were evaluated by ELISA. VDR FokI polymorphism was genotyped using the restriction fragment length polymorphism method. Results: No significant relationship was found between omega-3 fatty acids with perceived stress score or cortisol level in FF genotype carriers, but lower intake of PUFA was related to higher cortisol level (P=0.04) in Ff carriers. Significant interactions were observed between VDR FOKI polymorphism and intakes of eicosapentaenoic acid (EPA) (P Interaction=0.06), linoleic acid (P Interaction=0.06), and docosahexaenoic acid (DHA) (P Interaction=0.06) on serum cortisol, so that lower intake of EPA, linoleic acid, and DHA was associated with an increase in cortisol levels in individuals with ff genotype. Moreover, in carriers of ff genotype, lower intake of EPA was related to the elevated perceived stress score (P Interaction=0.06). Conclusion: FokI polymorphism interacts with omega-3 fatty acids (EPA, linoleic acid, and DHA) to increase cortisol level and with EPA to increase perceived stress score in nurses.