Inflammatory potential of diet and risk of colorectal cancer: a case-control study from Italy

Diet and inflammation have been suggested to be important risk factors for colorectal cancer (CRC). In the present study, we examined the association between the dietary inflammatory index (DII) and the risk of CRC in a multi-centre case-control study conducted between 1992 and 1996 in Italy. The study included 1225 incident colon cancer cases, 728 incident rectal cancer cases and 4154 controls hospitalised for acute non-neoplastic diseases. The DII was computed based on dietary intake assessed using a validated seventy-eight-item FFQ that included assessment of alcohol intake. Logistic regression models were used to estimate the OR adjusted for age, sex, study centre, education, BMI, alcohol drinking, physical activity and family history of CRC. Energy intake was adjusted using the residual method. Subjects with higher DII scores (i.e. with a more pro-inflammatory diet) had a higher risk of CRC, with the DII being used both as a continuous variable (ORcontinuous 1.13, 95% CI 1.09, 1.18) and as a categorical variable (ORquintile (5 v. 1) 1.55, 95% CI 1.29, 1.85; P for trend <0.0001). Similar results were observed when the analyses were carried out separately for colon and rectal cancer cases. These results indicate that a pro-inflammatory diet is associated with an increased risk of CRC.