Abstract
Compared to tocopherols, tocotrienols are poorly understood. The postabsorptive fate of tocotrienol isomers and their association with lipoprotein subfractions was examined. Normocholesterolemic women were subjected to an oral fat challenge supplemented with vitamin E (capsule containing 77 mg α-tocotrienol, 96 mgα-tocotrienol, 3 mg γ-tocotrienol, 62 mg α-tocopherol, and 96 mg γ-tocopherol). Plasma samples were collected at every 2 h intervals for up to 8 h following a one-time supplementation. Lipoproteins were measured by NMR spectroscopy, and subfractions of lipoproteins were isolated by density gradient ultracentrifugation. The maximal α-tocotrienol concentrations in supplemented individuals averaged approximately 3 µM in blood plasma, 1.7 µM in LDL, 0.9 µM in triglyceride-rich lipoprotein, and 0.5 µM in HDL. The peak plasma level corresponded to 12- to 30-fold more than the concentration of α-tocotrienol required to completely prevent stroke-related neurodegeneration. Tocotrienols were detected in the blood plasma and all lipoprotein subfractions studied postprandially.
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