FIGURE 6-6 Relationship of plasma α-tocopherol concentrations and hemolysis in extensively vitamin E-depleted (>72 months) and control subjects.

0 to 320 mg (0 to 744 µmol)/day, for up to 138 days. For the purpose of keeping the various supplemental forms of vitamin E administered in the study equivalent, the amounts of all rac-α-tocopheryl acetate and RRR-α-tocopheryl acetate administered were converted to amounts of 2R-α-tocopherol forms for this analysis (see Table 6-1 for conversions). The criterion for vitamin E adequacy was defined as an intake sufficient to increase plasma α-tocopherol concentration to or above 12 µmol/L (516 µg/dL).

SOURCE: Adapted from Horwitt et al. (1963).

As shown in Figure 6-7 using the data for intakes generated above (Table 6-5), plasma α-tocopherol concentrations were linearly (r² = 0.947) related to α-tocopherol intakes at intakes below 17 mg (40 µmol)/day. Using the limit of 12 µmol/L (516 µg/dL) plasma α-tocopherol as the criterion for the estimated vitamin E requirement generates a intake of 12 mg (28.2 µmol)/day α-tocopherol as the EAR.

Based on studies in normal and vitamin E-deficient children and adults, Horwitt et al. (1956), Farrell et al. (1982), and Sokol et al.