Associations of dietary intake with influenza susceptibility: evidence from bidirectional, multivariable, and mediation mendelian randomization analyses

Summary

This Mendelian randomisation study leveraged GWAS data from the UK Biobank (dietary factors) and FinnGen consortium (influenza outcomes) to investigate causal relationships between 25 dietary factors and influenza susceptibility across disease severity levels. Higher oily fish and fresh fruit intake showed protective associations with all influenza, whilst dried fruit intake was protective against severe influenza; dried fruit remained robustly associated after multivariable adjustment for socioeconomic and lifestyle confounders, though exploratory mediation analyses did not identify statistically significant mechanistic pathways after correction for multiple testing.

Regional applicability

The study used UK Biobank dietary exposure data linked to Finnish health registry outcomes from FinnGen, providing genetic evidence applicable to United Kingdom populations. The findings support potential public health messaging on dried fruit, oily fish, and fruit intake for influenza prevention, though UK implementation would require integration with existing nutritional guidance and consideration of seasonal influenza epidemiology.

Key measures

Inverse-variance weighted (IVW) MR estimates; odds ratios for influenza outcomes by dietary factor; multivariable MR adjusting for smoking, educational attainment, and household income; mediation analysis for vitamin E and DHA

Outcomes reported

The study evaluated causal associations between 25 dietary factors and three influenza outcomes (all influenza, regular influenza, and severe influenza) using genetic data. Primary findings included associations between oily fish intake and lower all-influenza risk, and dried fruit intake with lower severe influenza risk.

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