Objectives: Vitamin D is hypothesized to prevent periodontal disease through its immune modulatory mechanisms and its role in calcium homeostasis. Few studies have investigated the association of vitamin D status and biomarkers of oral inflammation. Our objective was to examine the cross-sectional association between vitamin D status and measures of four salivary cytokines and one serum cytokine among postmenopausal women in the Buffalo Osteoporosis and Periodontal Disease (OsteoPerio) Study, a ancillary study conducted in the University at Buffalo clinical center of the Women's Health Initiative (WHI) Observational Study.

Methods: We analyzed data from 710 participants from the OsteoPerio baseline (1997--2000) and 382 participants from the year-5 follow-up (2002--2005). Saliva and blood samples collected and stored frozen were tested for levels of vitamin D and cytokines. Multivariable linear regression was used to examine the association between plasma 25-hydroxyvitamin D (25[OH]D) concentrations, a biomarker of vitamin D status, and biomarkers of oral inflammation in saliva (Matrix Metalloprotinease-8 [MMP-8], Monocyte Chemoattractant Protein-1 [MPC-1], Tumor Necrosis Factor-alpha [TNF-alpha], and C-Reactive Protein [CRP]), and a biomarker of systemic inflammation (serum CRP), assessed using multiplex immunoassays. Cytokines concentrations were log-transformed for normality. Data on personal characteristics was determined by self-reported questionnaires. Censored data methods were used for concentrations above and below the limit of detection for inclusion in analysis. Multivariable models were adjusted for age, hormone use, frequency of tooth brushing, and days since last dental visit.

Results: Thirty-five percent of women at baseline and 19% at follow-up had deficient or inadequate vitamin D status (25[OH]D<50 nmol/L). Adjusted analyses showed an inverse association between 25(OH)D and salivary CRP at baseline (-7.13% change in salivary CRP concentrations per 10 nmol/L increase in 25(OH)D, 95% CI: -12.25 to -1.71, p=0.011) and at follow-up (-9.14%, 95% CI: -16.19% to -1.33%, p=0.023). Further adjustment for percent body fat (%BF), a strong predictor of 25(OH)D, attenuated this association at baseline (-2.58%, 95% CI: -7.91 to 3.07, p=0.364) and follow-up (-5.78%, 95% CI: -13.21 to 2.31, p=0.156). No statistically significant associations with plasma 25(OH)D were observed for salivary MMP-8, MCP-1, TNF-alpha, or serum CRP at baseline or follow-up.

Conclusion: Plasma vitamin D concentrations were found to be associated with salivary CRP concentrations, a biomarker of oral inflammation. The role of adiposity in this association needs to be further understood. Additional studies are needed to confirm these findings.