Causal relationships between dietary habits and lung cancer: A two- sample Mendelian randomization study

Abstract

Abstract Background Several studies have reported that dietary habits are associated with lung cancer (LUCA). However, the causal effects of dietary habits on LUCA incidence are still unclear because of uncontrolled confounding factors. Methods We obtained instrumental variables of associated with 5 genetically predicted dietary habits and applied two-sample Mendelian randomization (MR) to explore the causal effects of these variables on LUCA. In this study, inverse-variance weighting (IVW) was the main analysis, which was supplemented by MR‒Egger and the weighted median method. Results The IVW method revealed a causal relationship between never eating wheat products and an increased risk of LUCA (odds ratio (OR):1.032, 95% confidence interval (CI):1.005 ~ 1.059, P = 0.002 < 0.05). Eating eggs, dairy, wheat, and sugar was associated with a reduced risk of LUCA (OR = 0.967, 95% CI = 0.967 ~ 0.996, P = 0.014 < 0.05). No causal relationship was found between never eating sugar or foods/drinks containing sugar and LUCA (OR = 1.008, 95% CI = 0.989 ~ 1.027, P = 0.425 > 0.05). In addition, we used IVW and MR‒Egger to assess potential horizontal heterogeneity and pleiotropy, and no heterogeneity or pleiotropy occurred between the dietary variables and LUCA. Conclusion We found a positive association between never eating wheat products and LUCA scores. In addition, we found an inverse association between eating eggs, dairy, wheat, and sugar and LUCA scores. However, we found no evidence of a link between never eating sugar or foods/drinks containing sugar and LUCA in our MR results.