Men should not take high doses of vitamin E or selenium supplements because they have no health benefits and increase the risk of prostate cancer by up to a fifth, scientists have claimed.
Vitamin E, naturally found in nuts, spinach and broccoli, is taken to boost the body’s immune system and the mineral selenium, found in fish and meat, is taken to ward off heart disease. But US researchers claim large doses of both can increase the risk of prostate cancer by 17 per cent.
This can rise to as much as 91 per cent if a man already has high levels of selenium before taking supplements.
The warning centres on high-dose supplements, with researchers saying there appear to be no risks from taking a standard multivitamin.
But nor were there any apparent benefits from the supplements.
Lead researcher Alan Kristal, of the Fred Hutchinson Cancer Research Centre in Seattle, said: ‘Men using these supplements should stop, period.
Neither selenium nor vitamin E supplementation confers any known benefits, only risks.’
The study looked in detail at a past trial, carried out to test whether extra vitamin E and selenium could help prevent prostate cancer.
But instead, researchers discovered more cases of prostate cancer among men taking 400 international units (IU) of vitamin E daily than those taking a placebo.
This is the equivalent of 363mg a day, which is 30 times the recommended daily amount.
Men with low levels of selenium were the most affected by extra vitamin E – with the supplements raising their prostate cancer risk by 63 per cent.
Dr Kristal said: ‘Many people think that dietary supplements are helpful or at the least, innocuous. This is not true.
‘We know from several other studies that some high-dose dietary supplements – that is, supplements that provide far more than the daily recommended intakes of micronutrients – increase cancer risk.’
More than 35,000 healthy men in their 50s and older took part in the initial trial, which began in 2001. Further investigation of this data, published yesterday in the Journal of the National Cancer Institute, revealed the latest findings.
In the UK, the recommended daily amount of vitamin E is 12mg, and most multivitamin pills contain between 15mg and 30mg. However, the UK Expert Group on Vitamins and Minerals says the upper ‘safe’ limit is between 700 and 800mg a day – twice as much as taken in the trial.
Dr Matthew Hobbs, deputy director of research at Prostate Cancer UK, said more studies were needed, but added: ‘If men are concerned about their prostate cancer risk, rather than worrying about selenium and vitamin E supplements, they should talk to a GP.’
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