Causal association between dietary factors and telomere length revealed by mendelian randomization

Observational studies have reported associations between dietary factors and telomere length. However, the inherent limitations of observational study designs render them susceptible to confounding and reverse causation biases. Therefore, this study aims to explore the association between dietary factors and telomere length using Mendelian Randomization (MR) to minimize the influence of confounding factors and reverse causality. The IEU Open GWAS project was the source of exposure and outcome datasets. The exposure datasets included 20 dietary factors. We conducted MR analyses to explore the relationship between dietary factors and telomere length. We used MRPRESSO and Radial-MR test to identify any level of multi-effect outliers. Heterogeneity and pleiotropic analysis were performed to ensure the accuracy of the results. The stability of the effect of significant results is assessed using multivariable Mendelian randomization (MVMR) and MR-lap. Two-sample MR analysis revealed a statistically significant association between dried fruit intake and telomere length (β = 0.223, 95% CI 0.091 to 0.356, PIVW=9.089 × 10^-4). After removing outliers and reanalyzing the data, the association remained significant (β = 0.163, 95% CI: 0.163 0.090 to 0.235, PIVW−FE=7.323 × 10^-5), with no significant pleiotropy detected in sensitivity analyses. Following adjustment for confounders, the MVMR results and MR-lap results continued to support a causal relationship between dried fruit intake and telomere length. Other dietary factors’ effects on telomere length still need further confirmation. Our findings suggest a potential causal relationship between dried fruit intake and longer telomere length. This finding highlights potential dietary strategies for exploring the beneficial effects of dried fruit intake on preventing diseases and extending lifespan. © The Author(s) 2025.