Cancer, Diabetes Mellitus, Selenium, Vitamins

Bad news for vitamin E and cancer prevention

 The Journal of the American Medical Association (JAMA) reports 2 studies where vitamin E was not effective in preventing prostate cancer.

University of Texas M. D. Anderson Cancer Center in Houston

  • Researchers reanalyzed the results from the Selenium and Vitamin E Cancer Prevention Trial (SELECT) of 35,533 men.
  • Treatment compared selenium 200 µg/day, vitamin E 400 IU/day, selenium + vitamin E, and placebo in adult men for 7 to 12 years.
  • Neither the researchers nor the participants know the treatment — double-blind.
  • The authors concluded, “Selenium or vitamin E, alone or in combination at the doses and formulations used, did not prevent prostate cancer in this population of relatively healthy men.”

Physicians’ Health Study II Randomized Controlled Trial

  • Researchers studied the long-term effects of vitamin E or C supplementation on the risk of prostate and total cancer in men.
  • 14,641 male physicians (including 1307 men with a history of prior cancer) were studied for 8 years.
  • vitamin E 400 IU of every other day + vitamin C 500 mg of daily were compared to placebo.
  • Neither vitamin E nor C supplements reduced the risk of prostate or total cancer.

The bottom line?
Basic research provides a plausible mechanism for vitamins in preventing cancer, and this is supported by observational studies, say the Physicians’ Health Study researchers.

Neither of these studies reports harm during treatment, although the M. D. Anderson researchers briefly review the potential adverse effects from vitamin E, including an increase in the rate of death during treatment.

All this raises the question, “Why bother?”

At this time there’s no reason to take vitamin E 400 IU/day to prevent cancer.

This may change in the future as more is learned about specific groups of people who might benefit. For example, research in people with diabetes has revealed that although taking vitamin E doesn’t benefit every person with diabetes, there is a subgroup that can be identified — using a pharmacogenomic test — that do gain protection from the increased risk of cardiovascular complications.

If drugs are like hammers, CAM is closer to a feather. Accordingly, more sensitive tests are needed to predict who will benefit.

1/11/09 11:12 JR