Vitamin E supplements may slightly increase prostate cancer risk
Taking vitamin E supplements may be linked to an increased risk of prostate cancer, according to the results of a large US study published in the Journal of the American Medical Association.
Researchers from the Cleveland Clinic found that the disease was slightly more common among men who took a daily dose of the vitamin, than among those who were given a placebo (dummy) supplement.
The study, carried out between 2001 and 2004, involved more than 35,000 men in the US, Canada, and Puerto Rico.
Participants were given a daily dose of vitamin E, the mineral selenium, or a combination of the two. Another group of participants received a placebo supplement.
An initial analysis published in December 2008 showed that there was the possibility of an increased risk of prostate cancer among those given just the vitamin E supplements, but the data were not were not 'statistically significant' - in other words, the researchers could not be sure of the result.
However, the latest findings show that over time there was a statistically significant 17 per cent increase in prostate cancer rates among this group.
According to the study, of the 8,696 men taking a dummy pill, 529 developed prostate cancer, compared with 620 of the 8,737 men in the vitamin E group.
The researchers, led by Dr Eric A Klein, found that the increased risk only became evident during the third year of follow-up.
The researchers concluded: "The lack of benefit from dietary supplementation with vitamin E or other agents with respect to preventing common health conditions and cancers or improving overall survival, and their potential harm, underscore the need for consumers to be sceptical of health claims for unregulated over-the-counter products in the absence of strong evidence of benefit demonstrated in clinical trials."
Yinka Ebo, Cancer Research UK's senior health information officer said the study highlighted the importance of following study participants for long enough to be able to see a supplement's full effects.
"This study gives reason to be cautious with supplements - they don't substitute for a healthy diet, and as this and other studies have shown, they may even be harmful," she said.
"The best way to get the vitamins and minerals we need is by eating plenty of different types of fruit and vegetables, as part of a healthy, balanced diet."
Copyright Press Association 2011
- Klein, EA, et al: Vitamin E and the Risk of Prostate Cancer: The Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA. 2011;306:1549-1556