Tea intake and risk of kidney stones: a mendelian randomization study.

Objectives. Observational studies indicate that tea intake is associated with a decreased risk of kidney stones. Here we performed a mendelian randomization (MR) analysis to evaluate whether this association is causal. Methods. Forty-four independent genetic variants strongly associated with tea intake were identified from a large genome-wide association study, including 448060 individuals of the UK Biobank. We additionally obtained genome-wide association study summary statistics for kidney stones from the FinnGen consortium (5985 cases and 253943 controls) and UK Biobank (6536 cases and 388508 controls). Random-effect inverse variance weighted regression was used to evaluate causal estimates. The random-effect inverse variance weighted estimates based on the FinnGen consortium and UK Biobank were meta-analyzed using fixed-effects meta-analysis. Other MR methods, including MR-Egger, weighted median, weighted mode, and MR-Pleiotropy RESidual Sum and Outlier, were also performed to test the robustness of our results. Results. In a combined sample of 12521 cases and 642451 controls,...