AUTHOR=Zhao Hang , Jin Xiaolin 

TITLE=Causal associations between dietary antioxidant vitamin intake and lung cancer: A Mendelian randomization study

JOURNAL=Frontiers in Nutrition

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2022.965911

DOI=10.3389/fnut.2022.965911

ISSN=2296-861X

ABSTRACT=Background: Oxidative stress is currently considered to be closely related to the occurrence of respiratory tumours, especially lung cancer. Many observational studies have shown that increased antioxidant intake can reduce the risk of lung cancer, but the results are still controversial. We therefore performed a two-sample Mendelian randomized (MR) analysis in order to clarify the causal relationship between antioxidant vitamins and lung cancer.
Methods: To assess the causal effect of dietary antioxidant vitamin intake on lung cancer, we conducted a two-sample MR analysis and we extracted single-nucleotide polymorphisms (SNPs) which associated with antioxidants from genome-wide association studies (GWASs) of UK biobank. We gathered summary data for lung cancer from the International Lung Cancer Consortium (ILCCO), including 11,348 cases and 15,861 controls, and applied the inverse-variance weighted (IVW) method as the primary MR analysis, and performed sensitivity analysis to verify the results. 
Results: The results showed that higher dietary retinol intake was causally associated with lung cancer overall (OR = 1.844, 95% CI, 1.359-2.502, P = 0.00009), squamous cell lung cancer (OR = 2.162, 95% CI, 1.117-4.183, P = 0.022) and lung adenocarcinoma (OR = 1.706, 95% CI, 1.084-2.685, P = 0.021). Additionally, carotene was positively correlated with lung adenocarcinoma (OR = 1.510, 95% CI, 1.002-2.276, P = 0.049). However, there were nonsignificant relationship between the intake of other dietary antioxidants (vitamin C, and vitamin E) and lung cancer.
Conclusion: Our research showed that dietary retinol intake has an adverse impact on lung cancer, and carotene might increase the risk of adenocarcinoma. This highlights the importance of revealing the underlying mechanisms of dietary antioxidant vitamin in lung cancer and delivers an important health message that dietary antioxidant vitamin intake may not be necessary for the prevention of lung cancer. It also provides a basis for future research.