Effects of α-Tocopherol and Mixed Tocopherol Supplementation on Markers of Oxidative Stress and Inflammation in Type 2 Diabetes

Background: Vitamin E isomers may protect against atherosclerosis. The aim of this study was to compare the effects of supplementation with either α-tocopherol (αT) or mixed tocopherols rich in γ-tocopherol (γT) on markers of oxidative stress and inflammation in patients with type 2 diabetes. Methods: In a double-blind, placebo-controlled trial, 55 patients with type 2 diabetes were randomly assigned to receive (500 mg/day) ( a ) αT, ( b ) mixed tocopherols, or ( c ) placebo for 6 weeks. Cellular tocopherols, plasma and urine F2-isoprostanes, erythrocyte antioxidant enzyme activities, plasma inflammatory markers, and ex vivo assessment of eicosanoid synthesis were analyzed pre- and postsupplementation. Results: Neutrophil αT and γT increased (both P <0.001) with mixed tocopherol supplementation, whereas αT ( P <0.001) increased and γT decreased ( P <0.005) after αT supplementation. Both αT and mixed tocopherol supplementation resulted in reduced plasma F2-isoprostanes ( P <0.001 and P = 0.001, respectively) but did not affect 24-h urinary F2-isoprostanes or erythrocyte antioxidant enzyme activities. Neither αT nor mixed tocopherol supplementation affected plasma C-reactive protein, interleukin 6, tumor necrosis factor-α, or monocyte chemoattractant protein-1. Stimulated neutrophil leukotriene B4 production decreased significantly in the mixed tocopherol group ( P = 0.02) but not in the αT group ( P = 0.15). Conclusions: The ability of tocopherols to reduce systemic oxidative stress suggests potential benefits of vitamin E supplementation in patients with type 2 diabetes. In populations with well-controlled type 2 diabetes, supplementation with either αT or mixed tocopherols rich in γT is unlikely to confer further benefits in reducing inflammation.

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