title: A critical review of methodologies used in determination of relative bio-availability ratio of RRR-alpha-tocopheryl acetate and all-rac-alpha-tocopheryl acetate.
abstract: Bio-availability of different alpha-tocopherol forms in livestock animals is measured by the increase in plasma or tissue concentrations of alpha-tocopherol after oral administration. It is generally accepted that RRR-alpha-tocopheryl acetate (natural source vitamin E derived from vegetable oil) has a higher bio-availability compared to all-rac-alpha-tocopheryl acetate (synthetic vitamin E, i.e. alpha-tocopherol produced by chemical synthesis). However, different bio-availability ratios have been reported in the literature. The major reason for conflicting results in literature studies was the inability to separate the proportion of alpha-tocopherol originating from test materials, from the proportion of alpha-tocopherol originating from basal dietary ingredients and pre-feeding. This causes significant variability. For bio-availability determination, a baseline or control treatment is essential. The estimation of bio-availability without correction for basal vitamin E status will lead to incorrect interpretation of the results. When using proper methodologies, it is possible to correct for the impact of alpha-tocopherol intake from basal ingredients and alpha-tocopherol originating from pre-feeding, therefore yielding results reflecting the true relative bio-availability of different alpha-tocopherol substances. When reviewing literature data a critical evaluation of the method used in determination of relative bio-availability is recommended.
authors.affiliation: ADM Specialty Ingredients (Europe) B.V., Stationsstraat 76, Koog aan de Zaan, The Netherlands. Yueming.dersjant-li@adm.com
authors.forename: Yueming
authors.initials: Y
authors.lastname: Dersjant-Li
authors.forename: Manfred
authors.initials: M
authors.lastname: Peisker
mesh_terms: D000818:Animals; D001682:Biological Availability; D012107:Research Design / Q000592:standards*; D024502:alpha-Tocopherol / Q000008:administration & dosage / Q000138:chemical synthesis / Q000493:pharmacokinetics*
chemical_list: D024502:alpha-Tocopherol