Effects of alpha-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 alpha-tocopherol (alphaT) or mixed tocopherols rich in gamma-tocopherol (gammaT) 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) alphaT, (b) mixed tocopherols, or (c) placebo for 6 weeks. Cellular tocopherols, plasma and urine F(2)-isoprostanes, erythrocyte antioxidant enzyme activities, plasma inflammatory markers, and ex vivo assessment of eicosanoid synthesis were analyzed pre- and postsupplementation.


RESULTS
Neutrophil alphaT and gammaT increased (both P <0.001) with mixed tocopherol supplementation, whereas alphaT (P <0.001) increased and gammaT decreased (P <0.005) after alphaT supplementation. Both alphaT and mixed tocopherol supplementation resulted in reduced plasma F(2)-isoprostanes (P <0.001 and P = 0.001, respectively) but did not affect 24-h urinary F(2)-isoprostanes or erythrocyte antioxidant enzyme activities. Neither alphaT nor mixed tocopherol supplementation affected plasma C-reactive protein, interleukin 6, tumor necrosis factor-alpha, or monocyte chemoattractant protein-1. Stimulated neutrophil leukotriene B(4) production decreased significantly in the mixed tocopherol group (P = 0.02) but not in the alphaT 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 alphaT or mixed tocopherols rich in gammaT is unlikely to confer further benefits in reducing inflammation.
Wu
Jason H Y
JH
School of Medicine and Pharmacology, University of Western Australia, Crawley, Western Australia, Australia.
Ward
Natalie C
NC
Indrawan
Adeline P
AP
Almeida
Coral-Ann
CA
Hodgson
Jonathan M
JM
Proudfoot
Julie M
JM
Puddey
Ian B
IB
Croft
Kevin D
KD
D015415:Biomarkers / Q000032:analysis; D003924:Diabetes Mellitus, Type 2 / Q000178:diet therapy* / Q000378:metabolism; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007249:Inflammation / Q000178:diet therapy* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress; D024505:Tocopherols / Q000032:analysis / Q000627:therapeutic use*; D014815:Vitamins / Q000032:analysis / Q000627:therapeutic use*; D024502:alpha-Tocopherol / Q000032:analysis / Q000627:therapeutic use
D015415:Biomarkers; D014815:Vitamins; D024502:alpha-Tocopherol; D024505:Tocopherols