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Vitamin E may decrease and increase mortality of male smokers with high dietary vitamin C intake
14 February 2009
Helsingin yliopisto (University of Helsinki)
Six-year vitamin E supplementation decreased mortality by 41% in elderly male smokers who had high dietary vitamin C intake, but increased mortality by 19% in middle-aged smokers who had high vitamin C intake, according to a study published in the American Journal of Epidemiology.
Large-scale controlled trials have not found any overall effects of vitamin E supplementation on the mortality of participants. Nevertheless, the effect of vitamin E on respiratory infections has significantly diverged between different population groups suggesting that the effects of vitamin E may not be uniform over all the population.
Dr. Harri Hemila, and Professor Jaakko Kaprio, of the University of Helsinki, Finland, studied whether the effect of vitamin E supplementation on mortality might diverge between different population groups. They analyzed the data of the large randomized trial (Alpha-Tocopherol Beta-Carotene Cancer Prevention Study) which was conducted in Finland between 1985-1993 and included male smokers aged 50-69 years. There were 3571 deaths in 29,133 participants during the 6-year supplementation of 50 mg/day of vitamin E.
Although vitamin E had no overall effect on mortality, its effect was modified by age and dietary vitamin C intake. Vitamin E had no effect on participants who had low dietary vitamin C intake, less than 90 mg/day. However, in those who had high vitamin C intake, over 90 mg/day, the effect of vitamin E diverged so that it increased mortality in young participants (50-62 years), but decreased mortality in old participants (66-69 years).
The US nutritional recommendations, issued by the prestigious Institute of Medicine, consider that vitamin E is safe in doses up to 1000 mg/day. This new study gives further evidence indicating that in some population groups vitamin E may be harmful in a substantially lower dose, 50 mg/day.
The researchers concluded that "in people younger than 65 years, taking vitamin E supplements should be strongly discouraged, until clear evidence emerges that some population groups of younger or middle-aged people benefit". They also concluded that the effect of vitamin E on elderly people should be further investigated.