Association between dietary inflammatory index and oral cancer risk: A systematic review and dose–response meta-analysis

BACKGROUND: Dietary inflammatory index (DII) has been suggested to be associated with oral cancer risk. However, a quantitative comprehensive assessment of the dose–response relationship has not been reported. We performed a meta-analysis to clarify the risk of oral cancer with DII. METHODS: We searched PubMed, Embase, Cochrane Library, and Web of Science databases for relevant articles published up to 1 March 2022. Fixed- or random-effects models were utilized to estimate the pooled odds ratio (OR) of oral cancer with DII, as appropriate. Restricted cubic splines were used to model the dose–response relationship. RESULTS: We included five case–control studies involving 1,278 cases and 5,137 controls in the meta-analysis. Risk of oral cancer was increased by 135% with the highest versus lowest DII level [OR: 2.35, 95% confidence interval (CI): 1.88–2.94], and 79% with higher versus lower DII level (OR: 1.79, 95% CI: 1.49–2.15). We found no evidence of a nonlinear dose–response association of DII with oral cancer (p(non-linearity) = 0.752), and the risk was increased by 17% (OR: 1.17, 95% CI: 1.05–1.30) with 1 unit increment in DII score. CONCLUSION: This meta-analysis suggested that a higher DII score was associated with increased risk of oral cancer. Therefore, reducing pro-inflammatory components and promoting anti-inflammatory components of diet may be effective in the prevention of oral cancer.