0.45). The same factor would be used for the all rac-α-tocopherol acetate and succinate forms as well. See Table 6-1 for more information on the derivation of these conversion factors to be used when estimating intake from these forms of α-tocopherol to meet requirements.
mg of α-tocopherol in food, fortified food, or multivitamin = IU of the RRR-α-tocopherol compound × 0.67.
= IU of the all rac-α-tocopherol compound × 0.45.
The various vitamin E forms occur in different proportions in foods. The main dietary sources of vitamin E are edible vegetable oils (Dial and Eitenmiller, 1995; McLaughlin and Weihrauch, 1979; Sheppard et al., 1993) (Figure 6-8). At least half of the tocopherol content of wheat germ oil, sunflower oil, cottonseed oil, safflower oil, canola oil, and olive oil is in the form of α-tocopherol. Soybean and corn oils contain about 10 times as much γ-tocopherol as tocopherol. Palm and rice bran oils contain high proportions of tocopherol, as well as various tocotrienols (Dial and Eitenmiller, 1995). Other foods providing vitamin E include unprocessed cereal grains, nuts, fruits, vegetables, and meats, especially the fatty portion. As stated previously, all of the α-tocopherol present in these unfortified foods would be in the natural form, RRR-α-tocopherol and would contribute toward meeting the recommended dietary allowance. The other non-α-tocopherol forms of vitamin E present in food would not.
According to the 1994 to 1996 Continuing Survey of Food Intakes by Individuals (CSFII) (Appendix Table D-2), the median reported dietary intakes of men and women aged 31 through 50 years are 9.3 mg (21.6 µmol)/day and 6.8 mg (15.8 µmol)/day, respectively, of α-TE. Using the factor (0.8) derived from NHANES III data to determine α-tocopherol intake from α-TE, the adjusted intakes would be 7.5 mg (17.4 µmol)/day for men (9.3 × 0.8) and 5.4 mg (12.6 µmol)/day for women (6.8 × 0.8).