Does drinking tea prevent age-related macular degeneration? A cross-sectional and Mendelian randomization analysis

Purpose The potential protective effect of tea consumption on age-related macular degeneration (AMD) remains controversial. This study aims to investigate the association between tea consumption and AMD in a population-based cross-sectional analysis and evaluated causality using Mendelian randomization (MR), with external validation in an independent cohort. Design/methodology/approach A cross-sectional study combined with MR and external validation. The study included 2,328 adults aged ≥ 40 years from the National Health and Nutrition Examination Survey 2005–2006, including 227 participants with AMD. A multivariable logistic regression model was constructed to examine the association between tea consumption and AMD after adjustment for potential confounders. In a two-sample MR analysis, the authors analyzed summary-level data on tea consumption from the UK Biobank (447,485 cases) alongside published AMD genome-wide association study data (14,034 cases, 91,214 controls). External validation was conducted in 22,901 randomly selected adults aged ≥ 50 years from the community health service centers in Shanghai. Findings In the cross-sectional data, no significant dose-response relationship between tea consumption and AMD was observed (no tea consumption vs. 0–1 cup/day vs. > 1 cup/day: 8.8%, 7.5%, 8.0%, p = 0.74). Furthermore, multivariate logistic regression analysis indicated that, compared to non-tea-drinking, the odds ratios (ORs) for AMD in the 0–1 cup/day and > 1 cup/day groups were 1.146 (p = 0.51) and 1.098 (p = 0.75), respectively. In the inverse variance-weighted MR analysis, no causal relationship was found between tea consumption and AMD (OR = 1.21, 95% Confidence Interval [CI]: 0.91–1.62, p = 0.18). In external validation, the prevalence of AMD was 6.7% among tea-drinking group, which was comparable to that of non-tea-drinkers (6.9%, p = 0.64). Originality/value Drinking tea does not reduce the risk of AMD. No causal relationship between tea consumption and AMD could be established.