RÉSUMÉ
Introduction: Omega-3 polyunsaturated fatty acids (PUFAs) have been widely studied and used as nutritional supplements because of their anti-inflammatory effects. Previous studies have shown an association between polyunsaturated fatty acids such as omega-3 and omega-6 PUFAs with the development of malignant tumors. However, the relationships of omega-3 and omega-6 PUFAs with esophageal diseases have not been characterized. Methods: Mendelian randomization (MR) is a statistical method for identifying instrumental variables (IVs) from genome-wide association study (GWAS) data, and is associated with little confounding by environmental or other disease-related factors. We used genome-wide association study (GWAS) data from previously published studies on circulating concentrations of omega-3, omega-6, docosahexaenoic acid (DHA) and linoleic acid (LA), as well as esophageal cancer and other esophageal diseases, which were downloaded from the IEU OpenGwas database (https://gwas.mrcieu.ac.uk/) and the GWAS Catalog database (https://www.ebi.ac.uk/). The inverse variance-weighted approach was used as the principal analysis, and the MR-Egger and weighted median methods were used alongside. A series of sensitivity analyses were used to ensure the robustness of the causality estimates. Results: We found that the circulating omega-3 PUFAs concentration was positively associated with esophageal cancer (p = 8 × 10-4), and circulating DHA concentration (the main component of omega-3 in food), was also positively associated with esophageal cancer (p = 2 × 10-2), but no significant association was found between circulating omega-6 PUFAs and esophageal cancer (p = 0.17), and circulating LA concentration (the main component of omega-6 in food), was also no significant associated with esophageal cancer (p = 0.32). We found no significant relationships of circulating omega-3 and omega-6 PUFAs concentration with four other esophageal diseases. Conclusion: This study indicates that higher levels of circulating omega-3 PUFAs and DHA concentrations may be a risk factor for the development of esophageal cancer. Conversely, an increased omega-6/omega-3 ratio may serve as a protective factor against esophageal cancer. These findings have significant implications for the clinical application of omega-3 PUFAs and the prevention and treatment of esophageal cancer.
RÉSUMÉ
Utilizing a quantile frequency connectedness approach, we explore the connectedness between energy tokens, crypto market, and renewable energy stock markets. The empirical results show that the connectedness measures of the series are characterized by asymmetry and heterogeneity across quantiles and different investment horizons. Specifically, the characteristic of clustering has been observed that energy tokens and crypto market are more interconnected, while the renewable energy stock markets are more interconnected with each other at median quantile. The linkages between energy tokens and renewable energy stock markets are quite weak under normal market conditions, suggesting the diversification opportunities in investing these financial assets. However, these series are more interconnected under extreme market conditions, with the renewable energy stock markets are on the dominating end of the propagation mechanism while the energy tokens and crypto market are net receivers of shocks. Further frequency decomposition shows that this strategy can hold in the short term, while in the long term investors could benefit from the diversification opportunities by investing both kinds of financial assets. Additionally, the dynamic analysis affirms that the connectedness measures are varied and event-dependent over time. Our results may help investors and policymakers have a better assessment and portfolio management.