Dose-response association of dietary inflammatory potential with risk of cancer: systematic review and meta-analysis of prospective cohort studies

Observational studies indicated that the overall inflammatory potential of diets has been implicated in cancer etiology; however, the results were inconsistent. We aimed to estimate the dose-response association of dietary inflammatory potential with cancer outcomes based on prospective cohort studies. PubMed, Embase and Web of Science databases were searched up to 11 November 2023 for prospective cohort studies. The dietary inflammatory potential was assessed by the dietary inflammatory index (DII) or energy-adjusted DII (E-DII). Pooled relative risks (RRs) and 95% confidence intervals (CIs) were calculated using random-effects models. Restricted cubic splines were used to illustrate the possible linear or nonlinear associations. Ultimately, 30 articles including 33 studies with 4 090 977 participants were included. As compared the highest to the lowest DII category, the pooled RRs (95% CIs) for overall cancer, colorectal cancer, lung cancer, and renal cancer were 1.19 (1.11-1.27), 1.30 (1.16-1.44), 1.13 (1.04-1.23), and 1.45 (1.14-1.83), respectively; for E-DII, the RRs (95% CIs) was 1.08 (1.01-1.16) for overall cancer and 1.23 (1.13-1.33) for colorectal cancer. For each 1-unit increase in DII, the risk increased by 3% (RR = 1.03, 95% CI: 1.02-1.04) for overall cancer, 3% (RR = 1.03, 95% CI: 1.02-1.05) for colorectal cancer, and 7% (RR = 1.07, 95% CI: 1.03-1.12) for renal cancer; for E-DII, the risk increased by 1% (RR = 1.01, 95% CI: 1.00-1.02) for overall cancer and 3% (RR = 1.03, 95% CI: 1.02-1.05) for colorectal cancer. Additionally, restricted cubic splines showed linear relationships of DII (Pnonlinearity = 0.080) and E-DII (Pnonlinearity = 0.273) with overall cancer risk. The higher dietary inflammatory potential was associated with an increased risk of cancer.