A new study conducted by researchers at the University of Helsinki, Finland, has revealed that Vitamin E might increase tuberculosis risk in male smokers with high vitamin C intake.
In the study, Harri Hemila and Jaakko Kaprio, of the University of Helsinki, Finland found that six-year vitamin E supplementation increased tuberculosis risk by 72 percent in male smokers who had high dietary vitamin C intake, but vitamin E had no effect on those who had low dietary vitamin C intake.
Previous studies had suggested that vitamin E might improve the immune system and in animal studies it seemed to protect against various infections.
Keeping the previous studies in mind, the researchers carried out a study to determine whether vitamin E supplementation might decrease the risk of tuberculosis.
They analysed the data of the randomised trial, which was conducted in Finland between 1985-1993, and included male smokers aged 50-69 years.
There were 174 cases of tuberculosis in 29,023 participants during the 6-year supplementation of 50mg/day vitamin E.
The effect of vitamin E on tuberculosis risk was modified by the intake of vitamin C in diet.
The findings showed that Vitamin E had no effect on participants who had dietary vitamin C intake less than 90 mg/day.
However, it was also found that vitamin E supplementation increased tuberculosis risk by 72 percent in those who had dietary vitamin C intake over 90 mg/day.
The most dramatic increase in tuberculosis risk by vitamin E was restricted to a one-year period after the initiation of supplementation.
Issued by the prestigious Institute of Medicine, the US nutritional recommendations consider that vitamin E is safe in amounts up to 1000 mg/day.
However, this new study suggests that in some population groups vitamin E supplementation might be harmful at a substantially lower dose, 50 mg/day.
The researchers concluded 'the consumption of vitamin E supplements by the general population should be discouraged because there is evidence of harm for some people.'
The study is published in the British Journal of Nutrition.