NEW YORK, NY--(Marketwired - Apr 15, 2014) - The Selenium and Vitamin E Cancer Prevention Trial (SELECT) began 13 years ago under the hypothesis that selenium and vitamin E supplements could aid in reducing prostate cancer risk. Contrary to anticipated results, the long-term study demonstrated that high doses of each supplement, whether taken alone or together, actually increased a man's risk of developing prostate cancer.
"Once believed to prevent prostate cancer, these two supplements are now understood to pose a potential threat to some men," said David Samadi, robotic prostate surgery expert and Chairman of Urology and Chief of Robotic Surgery at Lenox Hill Hospital. "The results are a cautionary tale about adding supplements or unusual dietary changes without the counsel of a medical professional."
The SELECT study began in 2001 and included more than 35,000 men across 400 healthcare sites in the United States, Puerto Rico, and Canada. Seven years into the study, researchers reported no positive associations between prostate cancer prevention and vitamin E or selenium and instructed all participants to cease intake.
In 2011, researchers reported that men who took vitamin E alone for an average of 5.5 years had a 17 percent increased risk of developing prostate cancer. The results were documented at a follow-up of 1.5 years after participants stopped taking the supplements. Increased prostate cancer risk was also seen among men taking selenium alone and in conjunction with vitamin E -- as much as 91 percent -- in cases where selenium status was high at treatment initiation.
"From this data, researchers extrapolate that men over 65 who opt to take vitamin E supplements may face similarly increased rates of prostate cancer risk," explained Dr. Samadi. "This isn't to say that men should avoid vitamin E, particularly as part of a multi-vitamin regimen. Rather, men are encouraged to talk with their providers about prostate cancer risk factors and the necessity of supplements before taking them."
SELECT study participants were given 400 IU of Vitamin E per day and/or 200 mcg of selenium per day. More can be learned about the SELECT study in the publishing findings in the Journal of the National Cancer Institute, http://jnci.oxfordjournals.org/content/106/3/djt456.abstract?sid=f1e399bb-639e-4964-97bd-71306668777b. The study timeline is also detailed on the National Cancer Institute website,