Citrus fruit intake and incidence of renal cell carcinoma: A meta-analysis of observational studies

Observational studies on the association between citrus fruit intake and risk of renal cell carcinoma (RCC) have reported inconsistent results. We quantitatively assessed this association by conducting a meta-analysis. PubMed and Embase databases search was conducted including relevant studies published up to January, 2020. We included epidemiological studies that reported relative risks (RRs) or odds ratios (ORs) with 95% confidence intervals (CIs) for the association between citrus fruit intake and RCC risk. A total of eight epidemiological studies consisting of five cohort and three case-control studies were included. The overall analysis showed a significantly reduced risk of RCC for high intake of citrus fruit (OR = 0.84, 95% CI 0.73-0.95). No heterogeneity was detected among the included studies (p = 0.497 for heterogeneity; I² = 0). There was no significant publication bias by Begg's test (p = 0.266) or Egger's test (P = 0.578). A statistically significant association between citrus fruit intake and RCC was observed in case-control studies (OR = 0.84, 95% CI 0.71-0.98), while no association was observed in cohort studies (OR = 0.84, 95% CI 0.64-1.05). In addition, the dose-response analysis indicated that the RCC risk reduced by 13% (95%CI 1.0%-27%, p = 0.04 for heterogeneity) for each 100 grams per day increment of citrus fruit intake. In summary, our findings suggest an inverse association between citrus fruit intake and RCC incidence.