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DRI DIETARY REFERENCE INTAKES FOR Vitamin C, Vitamin E, Selenium, and Carotenoids
TABLE 9-1 Amounts in International Units (IU) of Any Forms of α-Tocopherola Contained in Vitamin Eb Supplements Equivalent to the UL for Adultsc
Sources of Vitamin E
Available as Supplements
UL for Adults
Total α-Tocopherol (mg/day)
IU from Source
Providing Adult UL
Synthetic Vitamin E and Esters
Natural Vitamin E and Esters
a All forms of supplemental α-tocopherol include all eight stereoisomers of α-tocopherol. The UL was based on animal studies feeding either all racemic- or RRR-α-tocopherol, both of which resulted in equivalent adverse effects.
b Vitamin E supplements have historically although incorrectly been labeled d- or dl-α-tocopherol (Horwitt, 1976). Sources of vitamin E include the all racemic- (dl-α-tocopherol [RRR-, RRS-, RSR-, RSS-, SSS-, SRS-, SSR-, and SRR-] or synthetic) form and its esters and the RRR-α-tocopherol (d-α-tocopherol or natural) form and its esters. All of these forms of vitamin E may be present in supplements.
c Conversion factors given in Table 6-1 to determine equivalency for meeting requirements are not directly applicable as they take into account lack of documented biological activity of 2S-forms of α-tocopherol in meeting requirements. The conversion factors used in this table are based on 2S-forms contributing to the adverse effects identified.
ble to estimate α-tocopherol intakes by multiplying the total α-TE in food (obtained from food composition tables) by 0.8. Also, the form of chemically synthesized α-tocopherol in fortified foods, multivitamin supplements, and vitamin E supplements has to be identified so that appropriate adjustments for activity can be made before calculating total intake of α-tocopherol.
Dietary intakes of selenium depend on the selenium content of the soil where the plant was grown or the animal was raised. Food animals in the United States and Canada usually have controlled diets to which selenium is added, and thus, the amounts found in muscle meats, milk, and eggs are more consistent than for plant foods.