Vitamin E does not blunt exercise-associated oxidative stress
MedWire News: Supplementation with vitamin E has no significant effect on the level of oxidative stress and inflammation associated with exercise, study findings suggest.
"Oxidative stress and inflammation play a major role in the pathogenesis of atherosclerosis-induced coronary artery disease (CAD)," explain the authors. "Exercise reduces the risk of CAD, and may paradoxically promote free-radical formation, lipid peroxidation, and vascular tissue injury."
Previous studies have shown that athletes who receive antioxidant supplements show reduced oxidative stress, but, until research confirms that the long-term use of antioxidants is safe and effective, the recommendation for physically active individuals to ingest a diet rich in antioxidants will remain questionable, they add.
In the present study, Sampath Parthasarathy (Ohio State University, Columbus, USA) and colleagues randomly assigned 455 healthy men and women to receive daily doses of vitamin E (800 IU) or placebo (controls), while participating in a 2-month exercise program.
The program required individuals to engage in at least 30 minutes of aerobic exercise three times per week. Blood samples were taken at 0, 2, 4, and 8 weeks.
As reported in the journal Nutrition, Metabolism and Cardiovascular Diseases, vitamin E supplementation had no significant effect on lipoprotein levels or markers of oxidative stress and inflammation in men or women after 8 weeks of exercise.
However, several measures of oxidative stress were seen to increase during the first 2 weeks of exercise in the control group. Indeed, levels of myloperoxidase (MPO) protein, lsoprostane, and auto-antibodies to oxidized low-density lipoprotein (AAOxLDL) cholesterol increased by 0.04 ng/ml, 0.38 pg/ml, and 0.02 OD, respectively, among females in the control group. Similarly, 2 weeks of exercise resulted in increases in MPO (0.64 ng/ml), AAOxLDL (0.01 OD), and OxLDL (0.35 U/l) levels among male participants in the control group.
Of interest, male and female participants in both the vitamin E and control groups exhibited decreases in high-sensitivity C-reactive protein (hs-CRP) levels after 2 weeks of exercise, remark Parthasarathy et al. However, only females on vitamin E and males on placebo continued lowering their hs-CRP until the end of the exercise program, reflecting a "gender and exercise extent dependent hs-CRP response."
The researchers conclude: "The association between exercise and reduction in CRP provides promising insights on future studies focusing on cardiovascular risk reduction and mechanisms on how exercise may improve the cardiovascular outcome."
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By Nikki Withers