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DRI DIETARY REFERENCE INTAKES FOR Vitamin C, Vitamin E, Selenium, and Carotenoids
(1984) concluded that plasma tocopherol concentrations alone may be misleading in assessing human vitamin E status because their data have indicated a dependence of plasma tocopherol concentrations on the amount of circulating lipids. Moreover, Winklhofer-Roob et al. (1997) found that age was a significant predictor of plasma α-tocopherol concentrations in 208 Swiss subjects aged 0.4 to 38.7 years. This apparent relationship was attributed to an age-related increase in serum cholesterol concentrations. Sokol et al. (1993) reported that, because of the extremely high serum lipids in children with cholestasis, a ratio of serum α-tocopherol to serum total lipids of less than 0.6 mg/g indicated vitamin E deficiency, regardless of serum α-tocopherol concentrations.
When evaluating the vitamin E status of an individual, plasma lipid levels should be taken into account because all of the plasma vitamin E is transported in plasma lipoproteins (Traber et al., 1993). In subjects with normal serum lipid concentrations (328 to 573 mg/dL) (Sokol et al., 1984), corrections are not necessary to assess whether α-tocopherol concentrations are within the normal range.
As described earlier, high intakes of PUFAs are typically accompanied by increased vitamin E intakes. Using data from NHANES II, Murphy et al. (1990) reported that the mean PUFA intake in the United States was 16.3 g/day for men and 10.8 g/day for women. Based on a ratio of at least 1 µmol (0.4 mg) α-tocopherol per gram of PUFA when the primary dietary PUFA is linoleic acid, as in most U.S. diets (Bieri and Evarts, 1973; Horwitt, 1974; Witting and Lee, 1975), and a mean intake of 16.3 g PUFA, the lower boundary of required α-tocopherol intake is estimated to be 7 mg (16 µmol)/day. Thus, the amount of α-tocopherol required daily based on PUFA intakes would be met by the EAR of 12 mg (28.2 µmol)/day of α-tocopherol.
Vitamin E EAR and RDA Summary, Ages 19 through 50 Years
Based on the criterion of vitamin E intakes sufficient to prevent hydrogen peroxide-induced hemolysis, the data of Horwitt (1960) support an EAR of 12 mg (27.9 µmol) of α-tocopherol. The data were derived from studies in men only, and no similar data are available for women. However, there is no scientific basis for assuming different requirements for men and women, and although body