Antioxidant effect on urinary excretion of malondialdehyde in non-athletes during aerobic training

Conditions in the body during aerobic exercise increase the level of lipid peroxidation (LP). LP is associated with elevated concentration of modified low-density lipoproteins that are implicated in development of cardiovascular disease. Supplementation with antioxidant vitamin E to athletes at 267 mg (400 IUs) or greater has been reported to reduce levels of LP associated with exercise. Little is currently known about the effects of modest supplementation of vitamin E on previously sedentary adults who initiate an aerobic fitness program. In the present study, sedentary subjects (n = 14) kept 24-hour diet records to establish antioxidant intake of vitamins E and C and collected 24-hour urine samples that were used to determine baseline urinary malondialdehyde (MDA) concentrations, one measure of in vivo LP. No significant differences were noted in the parameters between groups. Seven subjects were randomly selected and supplemented daily with 133 mg (200 IUs) of vitamin E. All subjects participated in moderate-intensity aerobic training for 8 weeks. Post-training, non-supplemented subjects excreted significantly more MDA (p<0.05) and consumed significantly fewer antioxidants than the supplemented group. Vitamin E supplementation appears to suppress elevated LP associated with beginning an aerobic exercise regimen in previously sedentary subjects.