Researchers at the Fred Hutchinson Cancer Research Center in seattle have published a study allegedly concluding that high doses of selenium and vitamin E supplements may increase the risk of prostate cancer, depending on a man’s selenium levels before taking the supplements. Alan Kristal, et al., “Baseline selenium status and effects of selenium and Vitamin E supplementation on prostate Cancer risk,” Journal of the National Cancer Institute, February 22, 2014.
The researchers had been running a follow-up trial to the 2005 selenium and Vitamin E Cancer Prevention Trial (SELECT) prostate cancer prevention study, which was set up to test earlier findings that selenium and vitamin e might reduce the risk of developing prostate cancer. that study, which involved 35,000 men, was stopped in 2008 when researchers found that the men taking the supplements appeared to be at a greater risk of developing aggressive prostate cancer.
Concluding that men who already had high concentrations of selenium in their bodies nearly doubled their risk of aggressive prostate cancer if they took selenium supplements, authors of the current study urge men using these supplements to stop immediately. the new study also revealed that (i) taking vitamin e alone boosted the risk of developing high-grade prostate cancer, but only in men who started the study with low selenium levels; (ii) taking selenium, either alone or in combination with vitamin e, increased the risk of high-grade prostate cancer in men who started the study with high selenium levels, but not in those with low selenium levels; and (iii) among men who did not take either vitamin e or selenium, those who started the study with high selenium levels were no more likely to have developed prostate cancer than men who started it with low selenium levels.
Commonly found in seafood and organ meats, such as liver, selenium is nutritionally essential for humans and plays roles in reproduction, thyroid hormone metabolism and Dna syntheses, as well as protecting against oxida- tive damage and infection. See Harvard Health Publications, February 28, 2014.