title: Effect of high-dose vitamin E on insulin resistance and associated parameters in overweight subjects.
abstract: OBJECTIVE
  Markers of oxidative stress and plasma alanine transferase (ALT) levels are increased and circulating antioxidant concentrations are reduced in individuals with insulin resistance. Vitamin E improves glycemic control in people with diabetes. We tested the hypothesis that vitamin E would decrease markers of oxidative stress and plasma ALT levels and improve insulin sensitivity in overweight individuals.
  
  
  METHODS
  Eighty overweight individuals (BMI >27 kg/m(2)) were randomly allocated to receive either 800 IU vitamin E per day or a matching placebo for 3 months. The dose of vitamin E was increased to 1,200 IU per day for a further 3 months.
  
  
  RESULTS
  Plasma peroxides decreased by 27% at 3 months and by 29% at 6 months in the group that received vitamin E and were positively correlated with plasma vitamin E concentrations at the 6-month time point. At 3 months, fasting plasma glucose and insulin concentrations were significantly reduced and homeostasis model assessment increased. These changes were not apparent at 6 months. Plasma ALT concentrations declined significantly throughout the study period.
  
  
  CONCLUSIONS
  In conclusion, these findings indicate that vitamin E improves oxidative stress and hepatocellular function. Although insulin resistance also improves, this effect appears transient.
authors.affiliation: Department of Medical and Surgical Sciences, University of Otago, Private bag, Dunedin, New Zealand. patrickmanning@healthotago.co.nz
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Manning
authors.forename: Wayne H F
authors.initials: WH
authors.lastname: Sutherland
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Walker
authors.forename: Sheila M
authors.initials: SM
authors.lastname: Williams
authors.forename: Sylvia A
authors.initials: SA
authors.lastname: De Jong
authors.forename: Anne R
authors.initials: AR
authors.lastname: Ryalls
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Berry
mesh_terms: D000328:Adult; D000368:Aged; D000975:Antioxidants / Q000627:therapeutic use; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000032:analysis; D004798:Enzymes / Q000097:blood; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000503:physiopathology*; D010919:Placebos; D012016:Reference Values; D014810:Vitamin E / Q000097:blood / Q000627:therapeutic use*
chemical_list: D000975:Antioxidants; D001786:Blood Glucose; D004798:Enzymes; D007328:Insulin; D010919:Placebos; D014810:Vitamin E; D002097:C-Reactive Protein