Dietary Inflammatory Index and Colorectal Cancer Risk—A Meta-Analysis
OBJECTIVE Chronic inflammation is implicated in causing cancer. Diet plays an important role in regulating chronic inflammation by altering circulating levels of inflammatory biomarkers. Effect of single food or nutrient on cancer often is inconclusive; perhaps due to dietary interactions and multicolinearity. The aim of this study was to determine prediagnostic inflammatory potential of overall diet in relation to risk for colorectal cancer (CRC). METHODS In all, 547 patients with CRC from Newfoundland Familial Colorectal Cancer Registry and 685 controls from the general population were identified. Data on sociodemographic, medical history, lifestyle, and a 169-item food frequency questionnaire were collected retrospectively from both groups. Energy-adjusted Dietary Inflammatory Index (DII) score was calculated and used as both categorical and continuous variables for analysis. Odds ratio was estimated using multivariable logistic regression after adjusting potential confounders. A linear test for trend was performed using the median value in each quartile. RESULTS Overall energy-adjusted mean DII score was -0.81 (range -5.19 to 6.93). Cases (-0.73 ± 1.5) had slightly higher DII scores than controls (-0.89 ± 1.6; P = 0.04). After adjusting the potential confounders, a statistically significant association was found between DII score and CRC risk. Using DII as a continuous variable (odds ratio [OR]continuous 1.10, 95% confidence interval [CI] 1.01-1.20) and categorical variable (ORquartile 1 versus 4 1.65, 95% CI 1.13-2.42; Ptrend = 0.02). CONCLUSION Our findings indicate that proinflammatory diets are associated with an increased risk for CRC in the Newfoundland population.