Green tea consumption and risk of esophageal cancer: A systematic review and dose-response meta-analysis: Running title: Green tea and esophageal cancer
Huilei Zhao Nutrition Available online 12 February 2021, 111197
Highlight
• Contrary to previous reviews, our exposure-effect meta-analysis showed 1 cup/day increase in green tea did not increased the risk of esophageal cancer. Neither nonlinearity nor linearity dose-response association was found between green tea and esophageal cancer risk.
• Based on current evidence, our study suggested there was a protective effect of green tea against esophageal cancer in females rather than in males.
Objective: Controversial results of the association between green tea consumption and risk of esophageal cancer (EC) were reported by previous meta-analysis. Thus, we performed a dose-response meta-analysis to quantitatively investigate the association.
Methods: The Cochrane Library, PubMed, and EMBASE databases were searched for relevant studies. We used a “one-stage approach” with a restricted cubic spline model to summarize the dose-specific relationships between green tea and risk of EC. Odds ratios (ORs) were used to measure the effects.
Results: In total, 14 studies were included with a total of 5,057 ECs among 493,332 participants. In the dose-response analysis, the summary OR for a 1 cup/day increase in green tea was 1.00 (95% CI: 0.95-1.04, I2=77%). No nonlinearity association was observed between tea consumption and risk of EC (P = 0.71 for nonlinearity). In the subgroup of sex, the summary OR for a 1 cup/day increase in green tea was 1.03 (95% CI: 0.95-1.11, I2=67%) for males and 0.79 (95% CI: 0.68-0.91, I2=0%) for females.
Conclusion: Contrary to previous studies, based current evidence, our dose-response study suggested there is no association between green tea and risk of EC. However, there might be a protective effect of green tea in females. Notably, our conclusion might be influenced by limited studies and potential bias, such as dose of green tea assessment and select bias of case-control studies. Further larger number, prospective and well-designed larger scale studies are needed to provide more precise evidence, especially in females and more regions (US and Europe).