Overdose of mineral supplements sharply increases risk of prostate cancer: Study
22 February 2014
Men have been warned against taking a pair of popular vitamin and mineral supplements after research showed they faced a dramatic rise in the risk of life-threatening prostate cancer.
Taking mineral selenium in quantities above the recommended dosage upped the chances of developing high-grade cancer by 91 per cent, according to scientists.
Vitamin E pills also raised the risk of aggressive cancer, more than doubling it for men lacking selenium.
According to researchers, selenium could turn toxic when present in the body at excessively high levels.
But there were also benefits by way of protection the mineral appeared to offer against the harmful effects of too much vitamin E.
The US study comes as a follow-up of Select, the selenium and vitamin E cancer prevention trial, which originally recruited over 35,000 men to see if the supplements could help prevent prostate cancer.
The trial was stopped by the researchers three years early in 2008, after it became apparent that rather than protecting men, vitamin E was putting them at greater risk, while selenium showed no benefit.
In another related development, scientists said DNA testing can predict which men faced the highest risk of deadly prostate cancer.
According to the team from the Institute of Cancer Research in London, men could soon be offered genetic screening in a way similar to breast cancer screening in women.
The team has shown 14 separate mutations could greatly up the odds of aggressive prostate cancers, which could form the basis of a test.
According to Prostate Cancer UK, such testing could "revolutionise" care for men.
Prostate cancer is the commonest cancer in men in many countries, including the UK, where over 40,000 people are diagnosed each year.
But, invasive therapy that leads to severe side effects is not needed in every patient.
Identification of who would need treatment - those who are likely to develop the most aggressive and deadly form of the cancer, remained a huge challenge.
The researchers collected blood samples from 191 prostate cancer patients and at least three close family members with the same condition.
Each underwent tests for risky mutations, including the BRCA genes involved in repairing DNA and already linked to breast and ovarian cancers.
According to the results published in the British Journal of Cancer, seven per cent of the men had one of 14 high-risk mutations.
The researchers added, it was also these men who had the aggressive prostate cancer that had started to spread around the body.