Written by Susan Sweeny Johnson, PhD, Biochem. After 19 years of followup, researchers assessed the incidence and type of prostate cancers of 29,133 Finnish male smokers and found that those with higher blood concentrations of alpha- tocopherol had a strongly reduced incidence of advanced cancers by almost 45%.
Vitamin E is a powerful antioxidant consisting of an assortment of tocopherols and tocotrienols. The most abundant form in the bloodstream is alpha-tocopherol. Several studies have found a link between reduced incidence of prostate cancer and blood concentrations of alpha-tocopherol and supplementation with vitamin E. (1-4).
The power of this study is the sheer number of participants allowing analysis of risks dependent on various forms of vitamin E in the bloodstream and different stages of prostate cancer. Of the 29,133 Finnish male smokers, ages 50 to 69 years recruited into the study, 1,732 were diagnosed with prostate cancer. Smokers provide a model for increased cancer that may also apply to the general population.
Initial blood concentrations of alpha-tocopherol were measured for each participant. They were also given a dietary questionnaire to assess their average intake of vitamin E and beta-carotene. Then participants were randomly assigned to receive either alpha-tocopherol (50 mg or 75 IU per day), beta-carotene as (20 mg or 33,333 IU per day), both supplements, or placebo capsules for 5 to 8 years. Over 19 years of follow-up, incidence and type of prostate cancer were assessed.
The results showed a strong correlation of reduced prostate cancer risk with higher blood concentrations of alpha-tocopherol. This correlation was more pronounced with vitamin E and beta-carotene supplementation, reducing risk a total of about 35%. Older men and those that smoked fewer cigarettes per day also saw some additional reduced risk when blood concentrations of alpha-tocopherol were elevated.
When types of prostate cancer were assessed, higher blood concentrations of alpha-tocopherol strongly reduced incidents of advanced cancers – about 45%.
Interestingly, dietary intake alone of various forms of vitamin E both from foods and supplements did not correlate with reduction in prostate cancer risk. This may be due to problems with dietary questionnaires of other unknown intake/blood concentration relationships which need further study. In addition, normal vitamin E levels of supplementation are usually much higher than those used in this study.
Source: Weinstein, Stephanie J., Margaret E. Wright, Karla A. Lawson, Kirk Snyder, Satu Männistö, Philip R. Taylor, Jarmo Virtamo, and Demetrius Albanes. “Serum and dietary vitamin E in relation to prostate cancer risk.” Cancer Epidemiology and Prevention Biomarkers 16, no. 6 (2007): 1253-1259.
© 2007 American Association for Cancer Research.
Posted July 1, 2008.
References:
- Huang HY, Alberg AJ, Norkus EP, Hoffman SC, Comstock GW, Helzlsouer KJ. Prospective study of antioxidant micronutrients in the blood and the risk of developing prostate cancer. Am J Epidemiol 2003;157:335 – 44.
- Kirsh VA, Hayes RB, Mayne ST, et al. Supplemental and dietary vitamin E, β-carotene, and vitamin C intakes and prostate cancer risk. J Natl Cancer Inst 2006;98:245 – 54.
- Heinonen OP, Albanes D, Virtamo J, et al. Prostate cancer and supplementation with a-tocopherol and h-carotene: incidence and mortality in a controlled trial. J Natl Cancer Inst 1998;90:440 – 6.
- Kristal AR, Stanford JL, Cohen JH, Wicklund K, Patterson RE. Vitamin and mineral supplement use is associated with reduced risk of prostate cancer. Cancer Epidemiol Biomarkers Prev 1999;8:887 – 92.
