Use of Stable Isotopes to Study Vitamin E Absorption and Metabolism in Human Subjects
Document Type
Article
Publication Date
12-1-1996
Description
The overall objective of this study was to examine the absorption and transport of vitamin E into plasma and bile using deuterium labeled tocopherol. In this experiment, we examined the relative contribution of newly absorbed ytocopherol and o-tocopherol to plasma and bile tccopherols. Two subjects undergoing operative common bile duct exploration were used for these studies. After undergoing common bile duct exploration for choledccholithiasis (gall stones within the common duct), a T-tube biliary drain was placed within the common duct until edema had resolved and normal bile flow had resumed Baseline blood and bile samples were taken prior to administering the tocopherols though a nasogastric tube. Prior to administration, the tccopherols were mixed with bile to promote solubilization. Subjects received three forms of deuterated tocopherol; ytocopherol (d2) (253 mg), RRR-a-tocopheryl acetate (d3) (173 mg), and allracemic-a-tocopheryl acetate (d6) (173mg). Endogenous a- and y-tocopherols (dO) were also measured. Blood and bile samples were obtained over time. Plasma lipoproteins were separated by rapid differential ultracentrifugation. Tocopherols in plasma, bile and lipoprotein fractions were extracted in hexane and quantitated by GC/MS with selected ion monitoring. All tccopherols were transported similarly in plasma with 46-62% in LDL, 17-35% in HDL with lesser amounts in chylomicrons and VLDL. y-tocopherol (d2) was enriched in bile compared to RRR-a-tocopherol (d3). Low levels of plasma y-tocopherol may be due to increased excretion into bile compared to a-tocopherol.
Citation Information
Kelley, J.; Compton, R.; Walters, D.; Thedford, S.; Wehh, L.; Papas, A.; and Acuff, Robert V.. 1996. Use of Stable Isotopes to Study Vitamin E Absorption and Metabolism in Human Subjects. FASEB Journal. Vol.10(3). ISSN: 0892-6638