Cheng Y, Kou F, Liu J, et al. - The present study was conducted to assess the relationship between environmental factors and gastroesophageal reflux disease (GERD) and evaluated their credibility. Researchers conducted systematic reviews and meta-analyses and for each meta-analysis, researchers considered the effect size, 95% confidence interval, the heterogeneity, small-study effects, P-value for excess significance and largest study significant, then they graded the evidence according to Assessment of Multiple Systematic Reviews and the GRADE assessment. The analysis included 23 publications (13 meta-analyses and 10 systematic reviews), which assessed 24 environmental factors. Varying levels of evidence were observed for different environmental factors of GERD. As per the findings, none of them was proven to be convincing or highly recommended.