Comparison of plasma alpha and gamma tocopherol levels following chronic oral administration of either all-rac-alpha-tocopheryl acetate or RRR-alpha-tocopheryl acetate in normal adult male subjects.

Vitamin E was administered orally (400 IU twice a day) to adult male humans for 28 days as either dl-a-tocopheryl acetate (all-rac-a-tocopheryl acetate) or d-a-tocopheryl acetate (RRR- a-tocopheryl acetate). Plasma a-tocopherol rose rapidly and fell at the same rate following cessation of supplementation with both forms of vitamin E. No significant differences in plasma a- or -y- tocopherol levels were found between the two forms of vitamin E following their administration. The results confirm the currently accepted biopotencies of 1.0 IIJ/mg and 1.36 lU/mg, respectively forthe two forms of vitamin E. Supplementation with eitherform of a-tocopheryl acetate resulted in depressing plasma y-tocopherol to <�/3 of initial levels; also the 7/a ratio was depressed to less than '/� of the initial value. The study suggests that the 7/a vitamin E ratio might also serve as a sensitive index of a-tocopherol ingestion. Am J Gun Nuir l986;43:382-387.