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Molecular detection of exercise-induced free radicals following ascorbate prophylaxis in type 1 diabetes mellitus:a randomised controlled trial

Davison, Gareth, Ashton, Tony, George, Lindsay, Young, Ian, Davies, Bruce, Jackson, Simon, Peters, John and Bailey, Damian (2008) Molecular detection of exercise-induced free radicals following ascorbate prophylaxis in type 1 diabetes mellitus:a randomised controlled trial. Diabetologia, 51 . pp. 2049-2059. [Journal article]

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DOI: 10.1007/s00125-008-1101-1


Aims/hypothesis Patients with type 1 diabetes mellitus aremore susceptible than healthy individuals to exercise-inducedoxidative stress and vascular endothelial dysfunction, whichhas important implications for the progression of disease.Thus, in the present study, we designed a randomised doubleblind,placebo-controlled trial to test the original hypothesisthat oral prophylaxis with vitamin C attenuates rest andexercise-induced free radical-mediated lipid peroxidation intype 1 diabetes mellitus.Methods All data were collected from hospitalised diabeticpatients. The electron paramagnetic resonance spectroscopicdetection of spin-trapped α-phenyl-tert-butylnitrone(PBN) adducts was combined with the use of supportingmarkers of lipid peroxidation and non-enzymatic antioxidantsto assess exercise-induced oxidative stress in malepatients with type 1 diabetes (HbA1c 7.9±1%, n=12) andhealthy controls (HbA1c 4.6±0.5%, n=14). Followingparticipant randomisation using numbers in a sealed envelope,venous blood samples were obtained at rest, after a maximalexercise challenge and before and 2 h after oral ingestion of1 g ascorbate or placebo. Participants and lead investigatorswere blinded to the administration of either placebo orascorbate treatments. Primary outcome was the difference inchanges in free radicals following ascorbate ingestion.Results Six diabetic patients and seven healthy controlparticipants were randomised to each of the placebo andascorbate groups. Diabetic patients (n=12) exhibited anelevated concentration of PBN adducts (p<0.05 vs healthy,n=14), which were confirmed as secondary, lipid-derivedoxygen-centred alkoxyl (RO·) radicals (anitrogen=1.37 mTand aβhydrogen=0.18 mT). Lipid hydroperoxides were alsoselectively elevated and associated with a depression ofretinol and lycopene (p<0.05 vs healthy). Vitamin Csupplementation increased plasma vitamin C concentrationto a similar degree in both groups (p<0.05 vs presupplementation)and attenuated the exercise-induced oxidativestress response (p<0.05 vs healthy).There were no selective treatment differences betweengroups in the primary outcome variable.Conclusions/interpretation These findings are the first tosuggest that oral vitamin C supplementation provides an effective prophylaxis against exercise-induced free radicalmediatedlipid peroxidation in human diabetic blood.

Item Type:Journal article
Faculties and Schools:Faculty of Life and Health Sciences
Faculty of Life and Health Sciences > School of Sport
Research Institutes and Groups:Sport and Exercise Sciences Research Institute
Sport and Exercise Sciences Research Institute > Centre for Physical Activity and Health
ID Code:5747
Deposited By: Professor Gareth Davison
Deposited On:04 Feb 2010 15:39
Last Modified:12 Feb 2014 15:10

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