Exploring Genetic Association of Tea Intake With Allergic Diseases Among European Population: A Bidirectional Mendelian Randomization Study

Previous observational studies focused on the association of tea intake and allergic diseases. However, it is not known whether these associations are causal. We used a bidirectional Mendelian randomization (MR) study to assess the causal relationship of tea intake with the risk of allergic diseases, such as atopic dermatitis (AD), allergic rhinitis (AR), and allergic asthma (AA). Single-nucleotide polymorphisms (SNPs) which had genetic statistical significance with tea intake were used as instrumental variables (IVs). We employed heritable IVs of tea intake from the UK Biobank, which included 447,485 samples. Sensitivity analyses were further performed using MR Egger and MR-PRESSO. Inverse variance weighted (IVW) method was used as the main approach. In this MR study, 40 independent SNPs were selected for tea intake. The MR analysis revealed that an increase in genetically predicted tea intake was associated with a lower risk of AD (OR = 0.709, 95% CI = 0.546-0.919, p = 0.009). Furthermore, we observed a causal effect of genetically predicted tea intake on the risk of AA (OR = 0.498, 95% CI = 0.320-0.776, p = 0.002). However, no significant causal relationship was found between genetically predicted tea intake and AR (OR = 1.008, 95% CI = 0.998-1.017, p = 0.115). Our MR analysis suggested that increased tea intake may reduce the risk of AD and AA in European population. This suggests that tea intake is likely a trigger or a prevention strategy for AD and AA.