Association between the inflammatory potential of the diet and incidence of metabolic syndrome in middle-aged adults

BACKGROUND & AIMS: Chronic low-grade inflammation is a central pathogenic mechanism underlying metabolic disorders, including obesity, type 2 diabetes, and cardiovascular disease. Metabolic syndrome (MetS) is closely associated with systematic inflammation, and dietary patterns are a major modifiable determinant of inflammatory status. However, prospective evidence on the association between dietary inflammatory potential and MetS incidence remains limited, particularly in Korean populations. METHODS: We analyzed 4890 adults (mean age: 50.4 years, 50.2% women) without MetS at baseline from the Ansan-Ansung cohort of the Korean Genome and Epidemiology Study. Dietary inflammatory potential was assessed using the newly developed Comprehensive Dietary Inflammation Index (CDII), derived from baseline food frequency questionnaire data. Incident MetS was defined using the National Cholesterol Education Program Adult Treatment Panel III criteria, and incident cases were defined as the first occurrence of MetS during the follow-up period from baseline through the 9th follow-up visit. Participants were categorized into CDII quartiles. Multivariable Cox proportional hazards models estimated hazard ratios (HRs) and 95% confidence intervals (CIs), adjusting for age, sex, residential area, total energy intake, drinking, smoking, physical activity, education, household income, and occupation. Additionally, associations between energy-adjusted residuals of individual food groups and MetS risk were examined to identify dietary components most strongly related to MetS. RESULTS: . Over 18 years of follow-up, 2301 participants (47%) developed MetS. Higher CDII scores were associated with increased MetS risk (quartile 4 vs. quartile 1: HR = 1.14, 95% CI: 1.04-1.25; P for trend = 0.006). Among individual CDII components, higher sugar-sweetened beverage (SSB) intake was associated with increased MetS incidence (HR = 1.0002, 95% CI: 1.0000-1.0003), whereas higher low-fat dairy intake was associated with decreased MetS incidence (HR = 0.999, 95% CI: 0.999-1.000). CONCLUSIONS: Higher dietary inflammatory potential, as measured by the CDII, was prospectively associated with an increased MetS risk in Korean adults. Although lower SSBs and higher low-fat dairy consumption were individually associated with a lower MetS risk, the overall dietary inflammatory profile appeared more relevant to metabolic health than single food groups.