Vitamin E: Risk Assessments, Meta-analysis, and Clinical Trials

摘要

Prospects for benefits from vitamin E intakes above recommended levels have led to the popularity of high-potency supplements. Several published risk assessments based on clinical trial data, and one on animal data conclude that vitamin E is safe at commonly consumed levels. Uncertainty is related to the strength and size of the clinical trials, extrapolation from animal data and comparison to outcomes at higher dosages in other trials. Outcomes of meta-analyses are evaluated in context of their methodologies and data inclusion criteria. The absence of a significant dose-response relationship casts doubt on the meta-analysis conclusion that daily doses of vitamin E > 400 IU is hazardous, Meta-analysis with a random effects model and Bayesian analysis found that vitamin E does not increase all-cause mortality. Most clinical trials have found no harm at any level of vitamin E intake; only one found statistically significant harm. Official Tolerable Upper Intake Level (UL) values are 300 mg or higher.