Role of tea in digestive tract malignancies: A two-sample Mendelian randomization study

There is no clear consensus on the association between tea intake and cancer, particularly its protective causal relationship with gastrointestinal tumors. This study aims to investigate this causal association using Mendelian randomization (MR) analysis to inform dietary interventions. This two-sample MR study utilized summary statistics on tea consumption from genome-wide association studies (GWAS) conducted by the UK Biobank (UKB) and Biobank Japan (BBJ). Data on gastrointestinal tumors were sourced from GWAS by the FinnGen consortium and BBJ. The causal relationship was assessed using methods such as inverse variance weighted (IVW), MR-Egger, and MR-PRESSO. Horizontal pleiotropy and heterogeneity of instrumental variables (IVs) were evaluated using MR-PRESSO and Cochran's Q tests. IVW estimates indicated that in the Asian population, tea intake was negatively associated with colorectal cancer risk (OR=0.372, 95%CI: 0.157–0.881). In the European population, higher green tea consumption was linked to a lower risk of malignant neoplasm of the small intestine (OR=0.940, 95%CI: 0.901–0.982). Tea intake may have a causal association with a reduced risk of colorectal cancer, offering new insights for its prevention. Further studies are needed to explore the specific protective mechanisms of tea consumption on gastrointestinal tumors.