title: The effect of vitamins C and E on biomarkers of oxidative stress depends on baseline level.
abstract: Oxidative stress is elevated in obesity, and may be a major mechanism for obesity-related diseases. Nonsmokers (n=396) were randomized to 1000 mg/day vitamin C, 800 IU/day vitamin E, or placebo, for 2 months. Treatment effect was examined in multiple regression analyses using an intention-to-treat approach. Vitamin C (P=0.001) and vitamin E (P=0.043) reduced plasma F2-isoprostanes. In the overall sample, changes from baseline were +6.8, -10.6, and -3.9% for placebo, vitamin C, and vitamin E groups, respectively. However, a significant interaction with baseline F2-isoprostane was found. When baseline F2-isoprostane was >50 microg/mL, vitamin C reduced F2-isoprostane by 22% (P=0.01). Vitamin E reduced it by 9.8% (P=0.46). Below that cut point, neither treatment produced further reductions. F2-isoprostane>50 microg/mL was strongly associated with obesity, and was present in 42% of the sample. Change in malondialdehyde concentration was minimal. These findings suggest a role for vitamin C in reducing lipid peroxidation. Future research on effects of vitamins C or E on plasma F2-isoprostane should limit participants to those with baseline levels >50 mug/mL. Further studies are needed to establish whether treatment with vitamins C or E in persons with concentrations above that cut point could slow the development of cardiovascular disease.
authors.affiliation: School of Public Health, University of California, Berkeley, CA 94720-7360, USA. gblock@berkeley.edu
authors.forename: Gladys
authors.initials: G
authors.lastname: Block
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Jensen
authors.forename: Jason D
authors.initials: JD
authors.lastname: Morrow
authors.forename: Nina
authors.initials: N
authors.lastname: Holland
authors.forename: Edward P
authors.initials: EP
authors.lastname: Norkus
authors.forename: Ginger L
authors.initials: GL
authors.lastname: Milne
authors.forename: Mark
authors.initials: M
authors.lastname: Hudes
authors.forename: Tapashi B
authors.initials: TB
authors.lastname: Dalvi
authors.forename: Patricia B
authors.initials: PB
authors.lastname: Crawford
authors.forename: Ellen B
authors.initials: EB
authors.lastname: Fung
authors.forename: Laurie
authors.initials: L
authors.lastname: Schumacher
authors.forename: Paul
authors.initials: P
authors.lastname: Harmatz
mesh_terms: D000328:Adult; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000494:pharmacology*; D015415:Biomarkers / Q000378:metabolism*; D028441:F2-Isoprostanes / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000378:metabolism; D018384:Oxidative Stress; D010919:Placebos; D012044:Regression Analysis; D014810:Vitamin E / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D015415:Biomarkers; D028441:F2-Isoprostanes; D010919:Placebos; D014810:Vitamin E; D001205:Ascorbic Acid