New numbers on Vitamin E and Selenium bleaker for Vitamin E

[JimJimJimJim]

A trial of 35,533 healthy men given Vitamin E and Selenium (one, both or a placebo) was stopped early (after 5.5 years) when no benefit was shown for either agent.

Even more worrying was a suggestion that Vitamin E may increase the risk of prostate cancer, and the Selenium may increase the risk of type 2 diabetes.

Now the 7 year mark has been reached. After 54,464 person-years of followup, enough evidence is in to confirm that vitamin E supplementation significantly increased risk of prostate cancer.

Selenium, though it did not prevent prostate cancer, was shown not to significantly increase the risk of type 2 diabetes.

Preclinical and epidemiologic evidence suggest that selenium and vitamin E may reduce risk of prostate cancer. The Selenium and Vitamin E Cancer Prevention Trial (SELECT) was a prospective randomized placebo-controlled study evaluating the effect of selenium and vitamin E on prevention of prostate cancer. The trial was discontinued following a preplanned interim analysis that demonstrated no benefit of either agent. Indeed, early follow-up (5.5 years) suggested instead an increased risk of prostate cancer following vitamin E treatment, and increased risk of type 2 diabetes following selenium treatment.

A total of 35,533 men were enrolled. Groups had similar rates of PSA and DRE testing. Since the initial report, there were an additional 54,464 person-years of follow-up. A total of 521 additional cases of prostate cancer have been reported, including 113 in the placebo group, 147 in the vitamin E group, 143 in the selenium group, and 118 in the vitamin E plus selenium group. The vitamin E group had a higher rate of prostate cancer detection compared with placebo (hazard ratio [hr.], 1.17; 99% CI, 1.004–1.36; P = .008). The interaction between vitamin E and selenium was significant after adjusting for marginal effects (P = .02), indicating that the combination of selenium and vitamin E did not increase risk of prostate cancer. Vitamin E increased risk of both low- and high-grade prostate cancer. Increased risk with vitamin E became apparent in the third year of the study and risk increased slightly with each subsequent year. There was an unadjusted increase in risk of cases of prostate cancer per 1000 person-years of 1.6 for vitamin E compared with placebo; the increased risk was 0.8 for selenium, and 0.4 for the combination. Unlike in the initial report, selenium was not associated with increased risk of type 2 diabetes.

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