The reported median vitamin E intake in the United States of all individuals surveyed in 1988 to 1994 in the Third National Health and Nutrition Examination Survey (NHANES III) was 9 mg (21 µmol)/day of α-TE (see Appendix Table C-3). Additional data from the NHANES III database indicate that α-tocopherol from food as defined in this report (the RRR-form) contributed approximately 7 mg/day of the 9 mg/day median intake of total α-TE (see Appendix Table C-4). Thus, based on NHANES III, approximately 80 percent of the α-TE from foods in the survey are reported to be contributed by foods containing α-tocopherol. Thus, to estimate the α-tocopherol intake from food surveys in the United States in which food intake data are presented as α-TE, the α-TE should be multiplied by 0.8:
mg of α-tocopherol in a meal = mg of α-tocopherol equivalents in a meal × 0.8.
If diets vary considerably from what might be considered typical in the United States and Canada, other factors may be more appropriate to use in place of 0.8.
To determine the number of milligrams of α-tocopherol in a multiple-vitamin supplement labeled in international units (IUs), one of two conversion factors is used. If the form of the supplement is “natural” or RRR-α-tocopherol (historically and incorrectly labeled d-α-tocopherol) (Horwitt, 1976), the correct factor is 0.67 mg/IU (USP, 1999). Thus, 30 IUs of RRR-α-tocopherol (labeled as d-α-tocopherol) in a multivitamin supplement would equate to 20 mg of α-tocopherol (30 × 0.67). The same factor would be used for 30 IUs of either RRR-α-tocopherol acetate or RRR-α-tocopherol succinate, because the amount in grams of these forms in a capsule has been adjusted based on their molecular weight. If the form of the supplement is all rac-α-tocopherol (historically and incorrectly labeled dl-α-tocopherol) (Horwitt, 1976), the appropriate factor is 0.45 mg/IU, reflecting the inactivity of the 2S-stereoisomers. Thus, 30-IU of all rac-α-tocopherol (labeled as dl-α-tocopherol) in a multi-vitamin supplement would equate to 13.5 mg of α-tocopherol (30 ×