Friend or Foe? Vitamin E vs Prostate Cancer

Don't get me wrong.  I don't purposefully mean to bash on dietary supplements (or prostate cancer for that matter) but rather pick & choose to comment on studies as they are published.  It's been said that the amount of information being published daily is more than enough to overwhelm any given individual over a lifetime.  So obviously, as the author of this blog, it's my prerogative to write about what I find interesting.

So with that said, let me first step into the way-back machine dialed for December 2008 when an analysis of SELECT (Selenium and Vitamin E Cancer Prevention Trial) was published in JAMA.  Concurrently, an analysis of the Physicians' Health Study II was published in the same issue of JAMA.  Both came to the same conclusion: vitamin E did not prevent prostate cancer in healthy men.

SELECT was a double-blind, placebo-controlled study of 35,533 men randomized to one of 4 options (selenium (200mcg/d L-selenomethionine) + placebo, vitamin E (400IU/d all rac alpha-tocopheryl acetate) + placebo, selenium + vitamin E, or placebo + placebo) and followed for 5+ years.  It should be noted that the study was originally planned for 7-12 years but stopped early because no benefit was demonstrated by vitamin E during that period of time.  More importantly, the authors had noted a statistically non-significant increase risk of prostate cancer in those randomized to vitamin E.

PHS II was a double-blind, placebo-controlled study of 14,641 male physicians at least 50yo at baseline randomized to placebo or vitamin E 400IU (synthetic alpha tocopherol) every other day plus vitamin C 500mg daily.  After 8 years, vitamin E demonstrated no benefit in reducing the risk of prostate cancer.

With that in mind, let's return to the present, where a new analysis of SELECT was just published in today's issue of JAMA after an additional 3 years of follow up of the original participants.  Their conclusion?  That originally statistically non-significant increase risk of prostate cancer was now a statistically significant increase risk of prostate cancer in those randomized to vitamin E.  Granted the hazard ratio was small at 1.17 but the fact remains that the increase risk is real, not just due to chance.  Put in absolute terms, for every 10,000 persons treated for a year w/vitamin E, 16 would develop prostate cancer compared to those who received a placebo.

Of course, it could be argued that PHS II did not use not an optimal dose of vitamin E but clearly, taking an "optimal" dose was harmful in the SELECT trial.  More importantly, in both studies, it could be argued that this specific vitamin E supplement was not ideal as it did not have the right mix of the various tocopherols, eg RRR-alpha (or ddd-alpha), RRR-beta, RRR-gamma & RRR-delta, that together make up what we call vitamin E.  With that said, unless one is very careful about choosing one's vitamin E, most of what's sold is synthetic racemic alpha tocopherol (marketed as dl-alpha tocopherol).

So while this trial answers the question of what happens from taking synthetic alpha tocopherol, it still leaves open the question of what happens from taking a balanced blend of tocopherols.  The point is that you probably shouldn't just blindly reach for a bottle of vitamin E if you're a guy but rather read the ingredient label carefully to determine the composition of tocopherols if you're a gambling man and feeling lucky.  Well, do ya?

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