Association between Dietary Inflammatory Index, C-Reactive Protein and Metabolic Syndrome: A Cross-Sectional Study

Increased prevalence of metabolic syndrome (MetS) has become a global major public health problem. Chronic low-grade inflammation associated with diet was found to play an import role in the development of MetS, although further studies are needed. The main purpose of this study was to explore the association between the dietary inflammatory index (DII), C-reactive protein (CRP) as a sign of inflammation status, and MetS. A total of 1712 participants from eight cities in China were included. Sociodemographic and health-related information was collected by a self-administrated questionnaire. Anthropometric information and fasting blood samples were collected for identification of MetS. DII scores were computed based on one time 24-h dietary recall. No significant association between MetS and DII was observed except for the blood pressure component of MetS (OR (T3 versus T1) = 1.40; 95% CI: 1.03 to 1.89). A significant increased prevalence for MetS was observed for higher CRP (OR = 1.66; 95% CI: 1.26 to 2.18), as well as four out of five of MetS components. In stratified analyses by sex, the associations between DII/CRP and MetS among women, but not men, are comparable to the whole sample. In addition, Both the 2nd and 3rd tertile of the DII had a higher CRP level (β-Coefficients (T2 versus T1) = 0.086, 95% CI: 0.004 to 0.167; β-Coefficients (T3 versus T1) = 0.145, 95% CI: 0.045 to 0.245) among subjects with MetS. Participants with higher DII scores reported a higher degree of “Shanghuo” (p = 0.007), which is a traditional concept characterized by “redness, swelling, fever and pain” in Chinese Medicine. This study suggested a close association between CRP and MetS, while the association between the DII and MetS was limited. DII was only specifically associated with CRP at a higher level among participants with MetS.