Tea intake and risk of kidney stones: A mendelian randomization study

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. Forty-four independent genetic variants strongly associated with tea intake were identified from a large genome-wide association study, including 448 060 individuals of the UK Biobank. We additionally obtained genome-wide association study summary statistics for kidney stones from the FinnGen consortium (5985 cases and 253 943 controls) and UK Biobank (6536 cases and 388 508 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. In a combined sample of 12 521 cases and 642 451 controls, the inverse variance weighted analysis indicated that genetically predicted tea intake was causally associated with a decreased risk of kidney stones (odds ratio = 0.47; 95% CI, 0.34–0.66; P < 0.001). This association was consistent in other MR methods. This study suggests that tea intake may be causally associated with a decreased risk of kidney stones.