Vitamin E intake and all-cause mortality: associations modified by smoking cessation duration in a US national cohort

Objectives This study aimed to investigate the association between vitamin E intake, its serum levels and all-cause mortality by smoking status. Participants This study included 30280 adults from National Health and Nutrition Examination Survey (NHANES) 1999–2014. We categorised participants into current smokers, former smokers and non-smokers. Measurements Vitamin E intake was assessed via a 24-hour dietary recall and categorised into tertiles. Serum vitamin E levels (alpha-tocopherol) were measured using high-performance liquid chromatography. Mortality data were obtained through linkage to the National Death Index. Results During a median follow-up of 119.7 months, 15.4% of participants experienced all-cause mortality. The former smokers were the oldest and had the highest proportions of men, hypertension, diabetes mellitus and chronic kidney disease. This group had the highest Body Mass Index, serum cholesterol, uric acid and urinary albumin creatinine ratio. The proportion of participants who met the recommended dietary allowance (RDA) of vitamin E was only 2491 (8.3%), and the RDA meeting rate was highest in the order of non-smokers, former smokers and current smokers. Cox regression analysis revealed that higher vitamin E intake was associated with lower mortality risks in former smokers and non-smokers, but not in current smokers. The association between vitamin E intake and mortality in former smokers was observed, particularly those who had quit smoking for more than 20 years. Serum vitamin E levels were associated with mortality only in non-smokers. Conclusions Vitamin E intake was not associated with a lower mortality risk in current smokers but was associated with lower mortality risk in former smokers and non-smokers. This finding suggests the importance of smoking cessation and the potential benefits of antioxidant vitamin E in former smokers.