Vitamin E Conversion Factors
Food Sources of Vitamin E

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.

Vitamin E Supplements

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 ×

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