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Supplementation with mixed tocopherols increases serum and blood cell -tocopherol but does not alter biomarkers of platelet activation in subjects with type 2 diabetes^1,2,3

¹ From the Department of Core Clinical Pathology and Biochemistry (MWC) and the School of Medicine and Pharmacology (MWC, NCW, JHYW, JMH, IBP, and KDC), Royal Perth Hospital, University of Western Australia, Perth, Australia

Background: Some studies have shown potential benefit of vitamin E on platelet function, but several clinical trials failed to show improved cardiovascular outcome with -tocopherol supplementation. -Tocopherol, a major dietary form of vitamin E, may have protective properties different from those of -tocopherol.

Objective: We compared the effects of supplementation with -tocopherol (500 mg) and a -tocopherol–rich compound (500 mg, containing 60% -tocopherol) on serum and cellular tocopherol concentrations, urinary tocopherol metabolite excretion, and in vivo platelet activation in subjects with type 2 diabetes.

Design: Fifty-eight subjects were randomly assigned to receive either 500 mg -tocopherol/d, 500 mg mixed tocopherols/d, or matching placebo. Serum, erythrocyte, and platelet tocopherol and urinary metabolite concentrations were measured at baseline and after the 6-wk intervention. Soluble CD40 ligand, urinary 11-dehydro-thromboxane B₂, serum thromboxane B₂, soluble P-selectin, and von Willebrand factor were measured as biomarkers of in vivo platelet activation.

Results: Serum -tocopherol increased with both tocopherol treatments. Serum and cellular -tocopherol increased 4-fold (P < 0.001) in the mixed tocopherol group, whereas red blood cell -tocopherol decreased significantly after -tocopherol supplementation. Excretion of -carboxyethyl-hydroxychroman increased significantly after supplementation with -tocopherol and mixed tocopherols. Excretion of -carboxyethyl-hydroxychroman increased significantly after supplementation with mixed tocopherols and after that with -tocopherol, which may reflect the displacement of -tocopherol by -tocopherol due to incorporation of the latter into lipoproteins in the liver. Neither treatment had any significant effect on markers of platelet activation.

Conclusions: Supplementation with -tocopherol decreased red blood cell -tocopherol, whereas mixed tocopherols increased both serum -tocopherol and serum and cellular -tocopherol. Changes in serum tocopherol closely reflect changes in cellular concentrations of tocopherols after supplementation.

Key Words: -Tocopherol • -tocopherol • diabetes • serum • erythrocytes • platelets • platelet function

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				J. H.Y. Wu, N. C. Ward, A. P. Indrawan, C.-A. Almeida, J. M. Hodgson, J. M. Proudfoot, I. B. Puddey, and K. D. Croft Effects of {alpha}-Tocopherol and Mixed Tocopherol Supplementation on Markers of Oxidative Stress and Inflammation in Type 2 Diabetes Clin. Chem., March 1, 2007; 53(3): 511 - 519. [Abstract] [Full Text] [PDF]