Radical protection for athletes.
For instance, Christopher Baldi and his colleagues at Ithaca (N.Y.) College assayed malondialdehyde (MDA), a characteristic marker of muscle oxidation, in 25 college-age women before and after a vigorous, 30-minute treadmill run. The exercise raised urinary MDA levels by 32 percent in women who did not receive supplements, the researchers found. Surprisingly, postexercise MDA levels fell by 28 percent among the remaining women, all of whom had taken 400 international units of vitamin E daily for three months. This suggests that antioxidants "may actually reverse oxidative stress during exercise," concludes Robert R. Jenkins, who led the study.
Ian Gillam of the Phillip Institute of Technology in Melbourne, Australia, and his colleagues recorded signs of a similar suppression of muscle oxidation in elite, high-endurance athletes after just four weeks of antioxidant supplements. The researchers recruited a total of 12 cross-country skiers, endurance runners and triathletes at the Australian Institute of Sport, an Olympic training center. Half took 1,000 international units of vitamin E and 1,000 milligrams of vitamin C daily; the rest received sugar pills. After four weeks, each group switched to the other's supplements.
After vitamin supplementation, "there was a 25 percent reduction in tissue oxidation," as evidenced by levels of two enzymes assayed in the blood, Gillam says. This suggests not only that the membranes in muscle -- and probably the heart -- are less damaged by oxidant stress during normal training if supplements are taken, but also that red blood cells sustain less damage, he says. Gillam's team also found signs that vitamins E and C altered concentrations of two hormones in the blood. A reduction in the normal ratio of testosterone to cortisol serves as a marker of "overtraining syndrome," a condition that can provoke a range of symptoms and diminish athletic performance. After supplementation, testosterone-cortisone ratios in these athletes actually increased.
"We don't have hard scientific evidence yet that we can improve [athletic] performance with antioxidant supplementation, but there's lots of evidence . . . that supplementation protects against damage [during training and competition]," concludes antioxidant specialist Lester Packer of the University of California, Berkeley, who organized a meeting session on this topic.
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|Title Annotation:||dietary supplements' effects|
|Article Type:||Brief Article|
|Date:||Jun 13, 1992|
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