title: 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.
abstract: Vitamin E was administered orally (400 IU twice a day) to adult male humans for 28 days as either dl-alpha-tocopheryl acetate (all-rac-alpha-tocopheryl acetate) or d-alpha-tocopheryl acetate (RRR-alpha-tocopheryl acetate). Plasma alpha-tocopherol rose rapidly and fell at the same rate following cessation of supplementation with both forms of vitamin E. No significant differences in plasma alpha- or gamma-tocopherol levels were found between the two forms of vitamin E following their administration. The results confirm the currently accepted biopotencies of 1.0 IU/mg and 1.36 IU/mg, respectively for the two forms of vitamin E. Supplementation with either form of alpha-tocopheryl acetate resulted in depressing plasma gamma-tocopherol to less than 1/3 of initial levels; also the gamma/alpha ratio was depressed to less than 1/7 of the initial value. The study suggests that the gamma/alpha vitamin E ratio might also serve as a sensitive index of alpha-tocopherol ingestion.
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D001682:Biological Availability; D004311:Double-Blind Method; D006801:Humans; D007700:Kinetics; D008055:Lipids / Q000097:blood; D008297:Male; D008875:Middle Aged; D011897:Random Allocation; D013237:Stereoisomerism; D024505:Tocopherols; D014810:Vitamin E / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism; D024502:alpha-Tocopherol / Q000031:analogs & derivatives*
chemical_list: D008055:Lipids; D014810:Vitamin E; D024502:alpha-Tocopherol; D024505:Tocopherols