A Mild Causal Relationship Between Tea Consumption and Decreased Risk for Obesity in General Population: A Two-Sample Mendelian Randomization Study

Background Tea consumption is considered as a protective factor for obesity. This study aimed to verify the casual association between tea consumption and obesity through a two-sample Mendelian randomization (MR) analysis in general population-based datasets. Methods The genetic instruments, single nucleotide polymorphisms (SNPs) associated with tea consumption habits, were obtained from genome-wide association studies (GWAS): UK Biobank, Nurses’ Health Study, Health Professionals Follow-up Study and Women’s Genome Health Study. The effect of the genetic instruments on obesity was analyzed using UK Biobank dataset (among ~ 500,000 participants). The causal relationship between tea consumption and obesity risk was analyzed by five methods of MR analyses: inverse variance weighted (IVW) method, MR-Egger regression method, weighted median estimator (WME), weighted mode and simple mode. Results Ninety-one SNPs were identified as genetic instruments in our study. A significant result was observed in IVW analysis (odds ratio [OR] = 0.998, 95% confidence interval [CI] = 0.996 to 1.000, P = 0.049]), which is the commonly used approach of two-sample MR analysis. Conclusion Our findings evidenced a mild causal relationship between tea consumption and the decreased risk for obesity. Further studies are needed to clarify the effects of tea consumption on obesity-related health problems in detail.