The potential benefits of tocopherol (otherwise known as vitamin E) for prostate cancer prevention have generated a great deal of interest for a number of years.
At first, tocopherol was thought to be a potentially beneficial nutrient in terms of lowering the risk of prostate cancer or of slowing its growth. However, today we know that vitamin E probably won't help.
Early StudiesNot that long ago, tocopherol was thought to provide some protection against the development of prostate cancer or to work to slow its progression. Several observational studies had been performed that seemingly showed that higher intake of vitamin E was associated with a lower risk of prostate cancer. Several other studies had shown that vitamin E might work to inhibit many of the functions of cancerous prostate cells.
Many major news organizations picked up on these stories, and soon much of the world thought of vitamin E/tocopherol as a potentially very beneficial supplement for prostate cancer prevention.
Despite several seemingly convincing studies showing the benefit of vitamin E for prostate cancer risk reduction, many physicians were unsure of its true benefits. Because the development and progression of prostate cancer is not fully understood and thought to be quite complex, many physicians were skeptical of the true potential benefits or harmful effects of a single mineral in this complicated disease evolution.
Many prominent researchers pushed for a large, well-organized study of the true benefits of vitamin E for prostate cancer prevention.
The SELECT TrialThe SELECT (the Selenium and Vitamin E Cancer Prevention Trial) trial was the first large, well-organized, comprehensively controlled study that sought to evaluate the benefits of both selenium and vitamin E for prostate cancer prevention. The study was monitored and organized by several well-respected researchers and research groups.
The SELECT trial enrolled more than 35,000 men who were randomly assigned to one of four groups over the course of several years. One group took one selenium and one vitamin E tablet daily. One group took one selenium and one placebo tablet daily. One group took one vitamin E and one placebo tablet daily. One group took two placebo tablets daily.
The SELECT trial overall showed no benefit in prostate cancer risk reduction from taking selenium or vitamin E supplements. In addition, the trial showed a slight increase in the rate of diabetes among the men who were taking selenium supplements and a slight increase in the rate of prostate cancer in the men taking vitamin E supplements.
Neither of these slight increases in medical conditions were found to be statistically significant (meaning these small increases could be due to chance); however, they were still troubling enough when coupled with the lack of benefits of the supplements, and trial was stopped early and the participants told to cease taking their supplements.
TodayDue in large part to the results of the SELECT trial, men today are generally no longer encouraged to take selenium and vitamin E supplements as a means to lower their prostate cancer risk.
Lippman SM, et al. Effect of Selenium and Vitamin E on Risk of Prostate Cancer and Other Cancers: The Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA. 2009;301(1):39-51