FIGURE 6-3 Plasma labeled (d3 and d6) α-tocopherols (means ± standard error, n = 6) following administration of a single dose containing 150 mg each d3RRR-α-and d6all rac-α-tocopherol acetates.

SOURCE: Adapted from Traber et al. (1998).

ment because of their failure to bind with the α-TTP. Thus, the Estimated Average Requirements (EARs), Recommended Dietary Allowances (RDAs), and Adequate Intakes (AIs) that follow apply only to intake of the 2R-stereoisomeric forms of α-tocopherol from food, fortified food, and multivitamins. The ULs apply to any forms of supplemental α-tocopherol.

Currently, most nutrient databases, as well as nutrition labels, do not distinguish between the different tocopherols in food. They often present the data as α-tocopherol equivalents and include the contribution of all eight naturally occurring forms of vitamin E (Figure 6-1), after adjustment for bioavailability of the various forms (see above). Because these other forms of vitamin E occur naturally in foods (e.g., γ-tocopherol is present in widely consumed oils such

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