Westernized diet is related to gastric cancer risk and inflammation, oxidative stress, and metabolic dysregulation: evidence from an incidence case-control study.

Westernized dietary patterns (WDPs), characterized by processed foods, red meats, refined grains, and added sugars, may contribute to gastric cancer (GC) development. We hypothesized that alignment with WDPs, as measured by the Westernized diet index (WDI), is associated with an increased risk of GC. In this incidence case-control study, 82 newly diagnosed GC patients and 95 age- and sex-matched controls were recruited. Dietary intake was assessed using a validated 168‑item food frequency questionnaire. Logistic regression models estimated odds ratios and 95% confidence intervals for GC across WDI categories, adjusting for major demographic, lifestyle, and clinical covariates, including Helicobacter pylori infection. To assess construct validity, fully adjusted linear regression evaluated associations between WDI scores and circulating inflammatory markers (high-sensitivity C-reactive protein, interleukin [IL]‑6, IL‑1β, IL‑10, tumor necrosis factor-alpha), oxidative stress (total antioxidant capacity, malondialdehyde), and metabolic biomarkers (body mass index, fasting glucose, lipid profile). Higher alignment with WDPs (lower WDI scores) was associated with significantly increased GC risk. Individuals in the highest WDI global Z‑score categories-WDI-G (food groups-nutrient based) and WDI-FG (food group based)-had 85% and 78% lower odds of GC, respectively (odds ratio = 0.15 and 0.19; both P < .001). Greater WDP alignment (lower WDI scores) was also associated with higher concentrations of high-sensitivity C-reactive protein, IL‑6, tumor necrosis factor-alpha, and IL‑1β, and lower IL‑10, along with an adverse metabolic profile (higher LDL‑c, lower HDL‑c). Overall, greater alignment with WDPs was associated with elevated GC risk and unfavorable biomarker patterns. These findings support the WDI as a biologically plausible indicator of Western dietary exposure and underscore the potential role of WDPs in gastric carcinogenesis.