Effects of Coffee, Black Tea and Green Tea Consumption on the Risk of Non-Hodgkin's Lymphoma: A Systematic Review and Dose-Response Meta-Analysis of Observational Studies

Aim: Several studies have evaluated the association between coffee, black and green tea consumption and non-Hodgkin's lymphoma (NHL) risk, while the results were inconsistent. We conducted a dose-response meta-analysis of available observational studies to assess the association among coffee, black and green tea intake and the risk of NHL in the general population.Methods: Studies published up to August 2018 were identified on the basis of a literature search in PubMed, ISI Web of Science, Scopus and Cochrane databases using Mesh and non-Mesh relevant keywords. Relative risks (RRs) with 95% confidence intervals (CIs) and the dose-response relationships were calculated using random-effects models.Results: In the meta-analysis of 19 effect sizes (315,972 participants with 4,914 cases of NHL), we found that higher green tea intake was associated with a 39% reduced risk of NHL (pooled RR=0.61; 95% CIs=0.38-0.99, I-2=60.4%, p(heterogeneity)=0.080) in high- versus low-intake meta-analysis. No association was observed between coffee intake (pooled RR=1.21; 95% CIs=0.97-1.50, I-2=52.6%, p(heterogeneity)<0.05), black tea intake (pooled RR=1.01; 95% CI=0.82-1.24, I-2=0%, p(heterogeneity)=0.875) and risk of NHL in high- versus low-intake meta-analysis.Conclusions: Findings from this dose-response meta-analysis suggest that green tea intake may be associated with reduced risk of NHL.