http://plaza.ufl.edu...euwen/April.PDF
SUPPLEMENTATION WITH VITAMIN C AND N-ACETYL-CYSTEINE
INCREASES OXIDATIVE STRESS IN HUMANS AFTER AN ACUTE MUSCLE
INJURY INDUCED BY ECCENTRIC EXERCISE
A. CHILDS, C. JACOBS, T. KAMINSKI, B. HALLIWELL, and C. LEEUWENBURGH*
Biochemistry of Aging Laboratory, Center for Exercise Science, College of Health and Human Performance, University of Florida,
Gainesville, FL, USA; and Department of Biochemistry, National University of Singapore, Kent Ridge Crescent, Singapore,
Singapore
(Received 1 May 2001; Accepted 15 June 2001)
Abstract—There has been no investigation to determine if the widely used over-the-counter, water-soluble antioxidants
vitamin C and N-acetyl-cysteine (NAC) could act as pro-oxidants in humans during inflammatory conditions. We
induced an acute-phase inflammatory response by an eccentric arm muscle injury. The inflammation was characterized
by edema, swelling, pain, and increases in plasma inflammatory indicators, myeloperoxidase and interleukin-6.
Immediately following the injury, subjects consumed a placebo or vitamin C (12.5 mg/kg body weight) and NAC (10
mg/kg body weight) for 7 d. The resulting muscle injury caused increased levels of serum bleomycin-detectable iron and
the amount of iron was higher in the vitamin C and NAC group. The concentrations of lactate dehydrogenase (LDH),
creatine kinase (CK), and myoglobin were significantly elevated 2, 3, and 4 d postinjury and returned to baseline levels
by day 7. In addition, LDH and CK activities were elevated to a greater extent in the vitamin C and NAC group. Levels
of markers for oxidative stress (lipid hydroperoxides and 8-iso prostaglandin F2a; 8-Iso-PGF2a) and antioxidant enzyme
activities were also elevated post-injury. The subjects receiving vitamin C and NAC had higher levels of lipid
hydroperoxides and 8-Iso-PGF2a 2 d after the exercise. This acute human inflammatory model strongly suggests that
vitamin C and NAC supplementation immediately post-injury, transiently increases tissue damage and oxidative
stress. © 2001 Elsevier Science Inc.
Keywords—Pro-oxidants, Ascorbic acid, Neutrophils, Sepsis, Free radicals, Disease, Antioxidants