Clinical Briefs: Vitamin E and Serum Hormone Levels
June 1, 2001 3 minutes read
Clinical Briefs
With Comments from John La Puma, MD, FACP
Vitamin E and Serum Hormone Levels
June 2001; Volume 4; 71-72
Source: Hartman TJ, et al. Effects of long-term alpha-tocopherol supplementation on serum hormones in older men. Prostate 2001;46:33-4638.
It is known that alpha-tocopherol supplementation significantly reduced the risk of prostate cancer in the Alpha-Tocopherol Beta-Carotene Cancer Prevention (ATBC) Study, and that sex hormones are thought to be involved in the etiology of prostate cancer. We examined whether long-term supplementation with alpha-tocopherol modified serum hormone levels.
Men who were cancer-free, consumed 90% of the study capsules, and had both baseline and follow-up blood available were eligible for the study. One hundred men who received alpha-tocopherol were matched by age, study center, and length of time between blood draws to 100 men who received placebo. Multivariate linear regression models, which allowed for a separate intercept for each matched pair, were used to evaluate the effect of alpha-tocopherol supplementation on follow-up hormone concentrations.
Compared to men who received placebo, we found significantly lower serum androstenedione (P = 0.04) and testosterone (P = 0.04) concentrations among men who received alpha-tocopherol, after controlling for baseline hormone level, follow-up serum cholesterol concentration, body mass index, smoking, and fasting time. Geometric mean (95% confidence interval [CI]) androstenedione concentration among men who received alpha-tocopherol was 145 ng/dl (CI 137-153 ng/dl) after adjusting for covariates, compared to 158 ng/dl (CI 148-167 ng/dl) among men who received placebo. Mean testosterone concentrations for men who received alpha-tocopherol and placebo were 539 ng/dl (CI 517-562 ng/dl) and 573 ng/dl (CI 549-598 ng/dl), respectively.
These results suggest that long-term alpha-tocopherol supplementation de- creases serum androgen concentrations, and could have been one of the factors contributing to the observed reduction in incidence and mortality of prostate cancer in the alpha-tocopherol treatment group of the ATBC Study.
Comment
Funded by the National Cancer Institute and the National Institutes of Health, this study adds fuel to the fat-soluble fire surrounding vitamin E. It is the supplement that is most closely associated with efficacy in prostate cancer, excepting PC-SPES (a mixture of eight herbs that causes estrogen-like adverse effects and PSA responses in patients with both androgen-dependent and refractory cancer). And these data, though few, support vitamin E use.
What is the mechanism? It is all hypothesis; synthesis, release, or destruction of androgen is somehow affected.
What is the downside of vitamin E use? Barrette reports: "In the ATBC study more episodes of hemorrhagic stroke were seen in those taking alpha-tocopherol than those not taking alpha-tocopherol.... (and) the incidence and mortality of subarachnoid hemorrhage were higher in the alpha-tocopherol subjects. However, the absolute rates were very low, e.g., 28 subarachnoid hemorrhage deaths in 14,238 taking alpha-tocopherol vs. 10 in 14,281 controls. Alpha-tocopherol also decreased the overall risk of the much more common cerebral infarction by 14% (95% CI, -25% to -1%; P = 0.03) and did not affect rates of intracerebral hemorrhage." (See Alternative Medicine Alert, Jan. 2001, pp. 1-5.)
In the Health Professionals’ Follow-up Study, a prospective cohort study of more than 40,000 men ages 40-75 followed for eight years, vitamin E intake and supplementation did not significantly affect hemorrhagic, ischemic, or total stroke rate.
Recommendation
Whether the benefit of vitamin E is limited to smokers is still up for debate. But with this writing, most men with prostate cancer can reasonably judge the benefit of the vitamin, 100 IU/d, to outweigh the risks.
June 2001; Volume 4; 71-72
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