Depending on the level of smoking and dietary vitamin C intake, vitamin E supplementation may extend the life-span of restricted groups of men, according to a study published in the Age and Ageing.

Several large randomized trials of humans found that vitamin E supplementation does not reduce mortality. However, the average effect on mortality in a group of people with a wide age range may mask an effect of vitamin E on the life-span.

Dr. Harri Hemila, and Professor Jaakko Kaprio, of the University of Helsinki, Finland, studied the age-dependency of vitamin E effect on mortality in the large randomized trial (Alpha-Tocopherol Beta-Carotene Cancer Prevention Study) which was conducted in Finland between 1985-1993. Their study was restricted to follow-up period over 65 years and 10,837 participants contributed to the analysis.

Among all analyzed participants, vitamin E had no effect on mortality when participants were 65 to 70 years old, but reduced mortality by 24% when participants were 71 or older.

Among 2,284 men with dietary vitamin C intake above the median who smoked less than a pack of cigarettes per day, vitamin E extended life-span by two years at the upper limit of the follow-up age span. In the other participants, consisting of 80% of the cohort, vitamin E did not affect mortality, which shows that vitamin E is no panacea for extending life expectancy.

The researchers concluded that "if vitamin E influences the life-span, it is possible that a benefit on the oldest participants might be camouflaged by the large middle-aged majority of study participants". Therefore, they propose that it might be useful to analyze the effect of vitamin E supplementation in large controlled trials by the age of the participant at the follow-up and not just by the time after randomization that has been customary.