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DRI DIETARY REFERENCE INTAKES FOR Vitamin C, Vitamin E, Selenium, and Carotenoids
around 45 mg (104.7 µmol)/day of α-tocopherol equivalents. This was the mean intake reported by women 51 through 70 years of age. However, the intake distribution from food and supplements is extremely skewed because the median intake of these women was about 9 mg (20.9 µmol)/day in comparison with a mean intake of 45 mg (104.7 µmol)/day. This group also had the highest reported intake at the ninety-ninth percentile of 508 mg (1,181 µmol)/day of α-tocopherol equivalents, which is well below the UL of 1,000 mg/day of any form of α-tocopherol. Vitamin E supplement use is high in the U.S. population (Hartz et al., 1988; Slesinski et al., 1996). In the 1986 National Health Interview Survey, supplements containing vitamin E were used by 37 percent of young children, 23 percent of men, and 29 percent of all women in the United States (Moss et al., 1989).
The risk of adverse effects resulting from excess intake of α-tocopherol from food and supplements appears to be very low at the highest intakes noted above. Although members of the general population should be advised not to exceed the UL routinely, intakes above the UL for vitamin E may be appropriate for investigation within well-controlled clinical trials. In light of evaluating possible benefits to health, clinical trials of doses of α-tocopherol above the UL should not be discouraged, as long as subjects participating in these trials have signed informed consent documents regarding possible toxicity and as long as these trials employ appropriate safety monitoring of trial subjects. Also, the UL is not meant to apply to individuals who are receiving vitamin E under medical supervision.
RESEARCH RECOMMENDATIONS FOR VITAMIN E
Biomarkers are needed for use in assessment of vitamin E intake and vitamin E status. What are the determinants of plasma concentrations of α-tocopherol, and are these concentrations regulated? Are plasma α-tocopherol concentrations the best parameter for assessing adequate plasma vitamin E status in apparently healthy individuals? Does an α-tocopherol/lipid (e.g., total lipid, triglyceride, or cholesterol) ratio better reflect optimal plasma vitamin E status?
Since the Recommended Dietary Allowances (RDAs) for children ages 1 through 18 years are extrapolated from the adult RDAs,