Mary L. Hardy

Effect of supplemental vitamin E for the prevention and treatment of cardiovascular disease

AbstractOBJECTIVE: To evaluate and synthesize the evidence on the effect of supplements of vitamin E on the prevention and treatment of cardiovascular disease. DESIGN: Systematic review of placebo-controlled randomized controlled trials; meta-analysis where justified. MEASUREMENTS AND MAIN RESULTS: Eighty-four eligible trials were identified. For the outcomes of all-cause mortality, cardiovascular mortality, fatal or nonfatal myocardial infarction, and blood lipids, neither supplements of vitamin E alone nor vitamin E given with other agents yielded a statistically significant beneficial or adverse pooled relative risk (for example, pooled relative risk of vitamin E alone=0.96 [95% confidence interval (CI), 0.84 to 1.10]; 0.97 [95% CI, 0.80 to 1.90]; and 0.72 [95% CI, 0.51 to 1.02] for all-cause mortality, cardiovascular mortality, and nonfatal myocardial infarction, respectively. CONCLUSIONS: There is good evidence that vitamin E supplementation does not beneficially or adversely affect cardiovascular outcomes.

Antioxidants Vitamin C and Vitamin E for the Prevention and Treatment of Cancer

OBJECTIVE: To evaluate the evidence of the supplements vitamin C and vitamin E for treatment and prevention of cancer.METHODS: Systematic review of trials and meta-analysis.DATA SOURCES AND MAIN RESULTS: Thirty-eight studies showed scant evidence that vitamin C or vitamin E beneficially affects survival. In the ATBC Cancer Prevention Study Group, no statistically significant effect of treatment was seen for any cancer individually, and our pooled relative risk (regardless of tumor type) for α-tocopherol alone was 0.91 (95% confidence interval [CI]: 0.74, 1.12). All cause mortality was not significant. In the Linxian General Population Trial, the relative risks for cancer death for vitamin C (combined with molybdenum) was 1.06 (95% CI: 0.92, 1.21) and for vitamin E (combined with β-carotene and selenium) was 0.87 (95% CI: 0.76, 1.00). We identified only 3 studies that reported statistically significant beneficial results: vitamin C (in combination with BCG) was found to be beneficial in a single trial of bladder cancer and vitamin E (in combination with ω-3 fatty acid) increased survival in patients with advanced cancer. In the ATBC trial, in analyses of 6 individual cancers, the prevention of prostate cancer in subjects treated with α-tocopherol was statistically significant (RR=0.64, 95% CI: 0.44, 0.94).CONCLUSIONS: The systematic review of the literature does not support the hypothesis that the use of supplements of vitamin C or vitamin E in the doses tested helps prevent and/or treat cancer in the populations tested. There were isolated findings of benefit, which require confirmation.