Background: antioxidants might protect against oxidative stress, which has been suggested as a cause of aging.
Methods: the Alpha-Tocopherol-Beta-Carotene (ATBC) Study recruited males aged 50-69 years who smoked at least five cigarettes per day at the baseline. The current study was restricted to participants who were followed up past the age of 65. Deaths were identified in the National Death Registry (1,445 deaths). We constructed Kaplan-Meier survival curves for all participants, and for four subgroups defined by dietary vitamin C intake and level of smoking. We also constructed Cox regression models allowing a different vitamin E effect for low and high age ranges.
Results: among all 10,837 participants, vitamin E had no effect on those who were 65-70 years old, but reduced mortality by 24% when participants were 71 or older. Among 2,284 men with dietary vitamin C intakes above the median who smoked less than a pack of cigarettes per day, vitamin E extended lifespan by 2 years at the upper limit of the follow-up age span. In this subgroup, the survival curves of vitamin E and no-vitamin E participants diverged at 71 years. In the other three subgroups covering 80% of the participants, vitamin E did not affect mortality.
Conclusions: this is the first study to strongly indicate that protection against oxidative stress can increase the life expectancy of some initially healthy population groups. Nevertheless, the lack of effect in 80% of this male cohort shows that vitamin E is no panacea for extending life expectancy.
Trial registration: ClinicalTrials.gov NCT00342992.