Abstract
A meta-analysis published in 2018 indicated a significant association between the dietary inflammatory index (DII) and risk of urologic cancers (UC). The number of included studies was limited, and more research has been published on this topic since then. The current study aimed to find a more precise estimate of the association between dietary inflammatory potential and risk of UC by updating the previous meta-analysis. The PubMed and Embase databases were searched between January 2015 and April 2023 to identify eligible articles. Combined relative risk (RR) and 95% confidence intervals (CI) were calculated by random-effects model to assess the association between dietary inflammatory potential and risk of UC by comparison of the highest versus the lowest category of the DII/empirical dietary inflammatory pattern (EDIP) or by using the continuous DII/EDIP score. The analysis, including 23 studies with 557,576 subjects, showed different results for UC. There was a significant association for prostate cancer among case-control studies (RR = 1.75, 95% CI: 1.34-2.28), whereas among cohort studies a null association was found (RR = 1.02, 95% CI: 0.96-1.08). For bladder cancer, a nonsignificant association was observed in both case-control (RR = 1.59, 95% CI: 0.95-2.64) and cohort studies (RR = 1.03, 95% CI: 0.86-1.24). Pooled RR from 3 case-control studies displayed a statistically significant association between the DII and risk of kidney cancer (RR = 1.27, 95% CI: 1.03-1.56). Although DII was positively associated with all types of UC, no association was found for EDIP. The present meta-analysis confirmed that an inflammatory diet has a direct effect on the development of prostate cancer and kidney cancer. Large-scale studies are needed to demonstrate the association between dietary inflammatory potential and risk of UC and provide effective nutritional advice for UC prevention. PROTOCOL REGISTRATION: The protocol was registered in the International Prospective Register of Systematic Reviews (CRD42023391204).