부산대학교 도서관

Background:The bioavailability of γ-tocopherol and metabolites of vitamin E after γ-tocopherol administration is not well understood. We investigated the effect of γ-tocopherol administration on the levels and metabolism of α- and γ-tocopherol in healthy volunteers.Methods:We measured two metabolites of vitamin E (2,5,7,8-tetramethyl-2-(2′-carboxyethyl)-6-hydroxychroman (α-CEHC) and 2,7,8-trimethyl-2-(2′-carboxyethyl)-6-hydroxychroman (γ-CEHC)) in plasma and urine by high-performance liquid chromatography with electrochemical detection (HPLC-ECD) during administration of γ-tocopherol. Two groups of volunteers were enrolled. The γ-tocopherol group received two γ-tocopherol capsules (each containing 186.4 mg of γ-tocopherol and 5 mg of α-tocopherol) for 28 days, while the control group received d-α-tocopherol at 5 mg/day, which was the same dose as that given to the γ-tocopherol group. Blood and urine samples were obtained on days 0, 14, 28, 35, 42, and 56 after the initiation of γ-tocopherol administration.Results:The plasma γ-tocopherol concentration increased markedly during administration of γ-tocopherol and the plasma γ-CEHC concentration increased along with that of γ-tocopherol. The plasma α-tocopherol concentration decreased significantly during γ-tocopherol administration. The plasma concentration of α-CEHC decreased significantly and urinary excretion of α-CEHC tended to increase in the γ-tocopherol group. Urinary sodium secretion was significantly increased at 1 week after the cessation of γ-tocopherol administration, but there was no significant difference of urine volume between the two groups.Conclusion:Metabolism of α-tocopherol is accelerated and the plasma α-tocopherol concentration is decreased during γ-tocopherol administration.European Journal of Clinical Nutrition (2005) 59, 900–905. doi:10.1038/sj.ejcn.1602154; published online 1 June 2005 [ABSTRACT FROM AUTHOR]