Exercise is known to increase the antioxidant capacity of the body. Muscles produce reactive oxygen species (ROS) during exercise. The body responds to these ROS by developing defenses to reduce the damage from the ROS generated during exercise. These defenses increase the antioxidant capacity of the body.
Many studies show that fruits and vegetables also protect against ROS damage in the body. But there are many theories as to how they reduce the damage. Because fruits and vegetables are high in antioxidants, one theory is that the antioxidants reduce the damage from ROS.
Ways Antioxidants Reduce ROS Damage
There are two possible ways antioxidants may reduce the damage. One is that the multiple antioxidants in fruits and vegetables directly interact with ROS generated by animal cells. They directly react with the ROS neutralizing them before the ROS can do damage. The second possible way is that they indirectly neutralize the ROS by stimulating protective cellular processes.
Although animal models and cell culture models have shown the protective effects of antioxidants, human clinical trials have failed to show protective effects. The cell culture models looked at the biochemical processes. And the animal studies looked at young and adult animals in early stages of disease development. Both these situations have well shown the protective effects.
Clinical Trials
However, clinical trials failed to show protective effects. One problem is that the trials included older patients with more advanced disease. These studies did not show any benefits of antioxidant supplements. These are the studies that are always mentioned when researchers say antioxidants are not helpful. In order for antioxidants to be shown helpful in these studies, though, the antioxidants would have to reverse advanced, possibly irreversible, disease – not just prevent it.
But there are also other possible explanations about why antioxidants may not be effective. One possible explanation is that they interfere with cellular protective mechanisms that are already present. A study from 2009 tried to determine if antioxidants reduce some of the protective effects of exercise.
Exercise And Antioxidant Supplements
This study (1) examined the interaction of exercise with the known antioxidants, Vitamin C (ascorbic acid) and Vitamin E. The researchers supplemented half the participants with Vitamin C 500 mg twice daily and Vitamin E 400 IU daily. Then they studied the response to exercise in those given supplements, and the response to exercise in those not given supplements. They found that the participants getting the supplements did not have as normal a response to oxidation from exercise as the participants not getting the supplements did. They concluded that antioxidants prevent the health promoting effects of exercise. Although they did show that these supplements blunt the increased insulin sensitivity from exercise, the conclusion that antioxidants prevent health promoting effects of exercise is too broad. It is an example of why you should not always accept the conclusions derived from a study.
The researchers studied markers for diabetes, which is a good analogue for cellular damage. Among other markers, they studied insulin sensitivity. Exercise normally gives an immediate improvement in insulin sensitivity shortly after the exercise period. This is one of the ways exercise protects against diabetes.
Training And Insulin Sensitivity
If you train regularly, this sensitivity continues to rise as you become more fit, until it is high even at rest. The researchers divided their groups into participants who trained regularly before the experimental period, and those who had not trained previously. The graphs in the study show that those who had not exercised previously could not get their insulin sensitivity even up to the level that those who trained previously had at rest.
The proper interpretation of the study is that when you have maximized your antioxidant capacity, the protective cellular effects of exercise have little room for improvement by external antioxidants. A supplement to the study showed that Vitamin C and Vitamin E protected the muscle cells from some of the oxidative stress produced by exercise. TBARS (a measure of oxidative stress in cells) in the muscle cells was much lower after exercise in those who took Vitamin C and Vitamin E. The antioxidants had protected the cells from at least some oxidative damage.
Antioxidant Capacity Of Foods
Although research has a long way to go in understanding antioxidant protection in the cell, many studies seem to indicate antioxidants may help. Only a few seem to indicate harm in a few select situations. In any case, there are a great many studies that show that foods that are high in antioxidants are helpful to health. It may be that something else in the food besides the antioxidants is the helpful component.
Because the test tube measurement of antioxidant capacity of food does not correlate with the cellular action, (discussed here), it may well be something else, besides the antioxidants in the food, promotes health.
Nonetheless, foods high in antioxidants should still be an important part of your diet. These are some of the foods that also have very high potassium sodium ratios. And the high potassium sodium ratio is well established as an important, if not the most important, factor in a healthy diet to prevent high blood pressure, cardiovascular disease, stroke, osteoporosis and kidney stones.
Tables Of High Potassium Foods
To find tables of high potassium foods, look at the “Links to Food Potassium Tables” page. There is a tab linked to it at the top of this page.
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1. Antioxidants prevent health-promoting effects of physical exercise in humans. Ristow M, Zarse K, Oberbach A, Klöting N, Birringer M, Kiehntopf M, Stumvoll M, Kahn CR, Blüher M. Proc Natl Acad Sci U S A. 2009 May 26;106(21):8665-70. doi: 10.1073/pnas.0903485106. Epub 2009 May 11.
