Relative biological values of d-alpha-tocopheryl acetate and all-rac-alpha-tocopheryl acetate in man.

A reexamination of the biological potency of compounds with vitamin E activities has been made. Special attention has been paid to the relative potencies of d-alpha-tocopheryl acetate and all-rac-alpha-tocopheryl acetate since these two forms provide most of the dietary and clinical supplementations used. Distinctions have been drawn between the vitamin E requirements and metabolism of animals, from which most previous calculations have been made, and the ability of adult males to retain the tocopherols in their blood. Previously published data from analyses of plasma from vitamin E-depleted subjects, who had been quantitatively supplemented for 138 days with different levels of the tocopherols, were analyzed. The evaluations showed that all-rac-alpha-tocopheryl acetate may have no more than half the biological potency of d-alpha-tocopheryl acetate when used as a supplement for vitamin E-depleted adult subjects.