The association between fruit and vegetable intake and gastrointestinal cancers risk from Mendelian randomization analysis

Recent research has demonstrated a relationship between fruit and vegetable intake and gastrointestinal cancers, but the causality of these associations remains uncertain. This investigation sought to elucidate whether there is a potential causal relationship between the intake of fruits and vegetables and the risk of gastrointestinal cancers. Employing two-sample Mendelian randomization (MR), this research explored the causative influence of consuming fruits (fresh and dried) and vegetables (salads/raw and cooked) on the susceptibility to gastrointestinal cancers. The UK Medical Research Council-Integrative Epidemiology Unit (MRC-IEU) provided the summary statistics for these exposure variables, while the summary statistics for outcome data came from four other data sources. Univariable and multivariable MR were performed using inverse variance-weighted (IVW), MR-Egger, weighted media (WM), and Lasso model methods. Besides, multiple methods were employed for sensitivity analyses to guarantee the robustness of the findings, including MR-Egger intercept, Cochran's Q test, and MR-PRESSO. Furthermore, the Phenoscanner V2 database was employed to identify possible confounders. The main analysis of univariable MR found that dried fruit consumption provided protection against pancreatic and oral cavity/pharyngeal cancers. However, this correlation becomes non-significant when potential confounders such as smoking, drinking, and body mass index (BMI) are accounted for. Furthermore, neither univariate nor multivariate MR analyses revealed enough data to prove a causal relationship between the intake of fresh fruit, vegetables (including salad/raw and cooked), and gastrointestinal cancers. There is insufficient evidence for a causal association between the consumption of fruits and vegetables and the occurrence of gastrointestinal cancers. Further empirical research is needed to corroborate these dietary factors' role in the etiology of gastrointestinal cancers.