Clinical trials show high levels of the mineral Selenium can raise chances of developing high-grade cancer by 91%
Men have been warned not to take a pair of popular vitamin and mineral supplements after research showed they can dramatically increase the risk of life-threatening prostate cancer.
Overdosing on the mineral selenium by taking supplements raised the chances of developing high-grade cancer by 91%, scientists found.
Vitamin E pills also boosted the risk of aggressive cancer, more than doubling it for men lacking selenium.
The researchers believe selenium can turn toxic when present in the body at excessively high levels.
At the same time, the mineral appeared to protect against the harmful effects of too much vitamin E.
The US study was a follow-up of Select, the selenium and vitamin E cancer prevention trial, which originally recruited more than 35,000 men to see if the supplements could help prevent prostate cancer.
Researchers stopped the trial three years early in 2008 after there were hints that instead of protecting men, vitamin E was putting them at greater risk, while selenium showed no benefit.
A subsequent comparison of 1,739 participants diagnosed with prostate cancer and 3,117 matched cancer-free individuals highlighted the supplement hazards.
Study leader Dr Alan Kristal, from the Fred Hutchinson Cancer Research Centre in Seattle, said: “These supplements are popular – especially vitamin E – although so far no large, well-designed and well-conducted study has shown any benefits for preventing major chronic disease.0