Abstract
BACKGROUND: Vitamin E plays a crucial role in cellular protection, supporting the immune system. This study aims to explore the impact of dietary vitamin E intake on all-cause mortality, cause-specific mortality, and life expectancy.
METHODS: This study included 12 977 participants from the US National Health and Nutrition Examination Survey (NHANES) cohort and 70 369 participants from the UK Biobank cohort. Participants were divided into three groups (lower, higher, and highest tertiles) based on their vitamin E intake levels. The primary outcomes were all-cause, cardiovascular disease (CVD), and cancer mortality across the three groups in both cohorts. The secondary outcome was life expectancy in participants with diabetes, CVD, and hypertension across the three groups.
RESULTS: After multivariable adjustment, participants in the highest tertile in the US NHANES cohort had a 32% lower risk of mortality [hazard ratio (HR) 0.68, 95% confidence interval (CI) 0.55-0.84] compared with those in the lowest tertile. In the UK Biobank cohort, participants in the highest tertile had a 7% lower risk of mortality compared with those in the lowest tertile (HR: 0.93, 95% CI: 0.86-0.99). A significant association between vitamin E intake and CVD mortality was observed in the US NHANES, but this association was not found in the UK Biobank. In the US NHANES, participants in the highest tertile of vitamin E intake with diabetes, CVD, or hypertension had a 33-35% lower risk of all-cause mortality. In the UK Biobank, the highest tertile was associated with a 13% (95% CI: 0.78-0.97) and 9% (95% CI: 0.83-1.00) lower risk of all-cause mortality for CVD and hypertension, respectively. Nonlinear threshold effects of dietary vitamin E intake on all-cause mortality were observed, with changepoints at 6.68-13.70 mg/day in the UK Biobank and 4.78-36.95 mg/day in the US NHANES. Population attributable fraction analysis indicated that approximately 3.65-10.29% of all-cause mortality could be attributed to low dietary vitamin E intake. Compared with the general participant population, those with underlying conditions such as diabetes, CVD, and hypertension showed a significant increase in life expectancy.
CONCLUSION: Higher dietary vitamin E intake was associated with lower all-cause mortality, with stronger associations observed in the US NHANES cohort and weaker effects in the UK Biobank. Dose-response analyses indicated a nonlinear relationship, with protective effects concentrated within an optimal intake range rather than increasing indefinitely.