Free radicals are the 'baddies'! They are atoms or groups of atoms with an odd number of electrons in their configuration. They can be formed when oxygen reacts with certain molecules. Once formed these very reactive radicals can start chain reactions. They can react with important cellular components such as DNA, or the cell membrane resulting in the cells performing badly or even dying. Antioxidants are the bodies defense system against these free radicals.
Antioxidants have the ability to safely react with free radicals and terminate the chain reaction before cells are damaged. There are several enzyme systems within the body that mop up free radicals. The primary antioxidants are vitamin E, beta-carotene, and vitamin C. Also, selenium (a trace metal). The body cannot manufacture these antioxidants so they must be supplied in the diet.
Vitamin E : A fat soluble vitamin found in nuts, seeds, vegetable and fish oils, whole grains, fortified cereals, and apricots.
Vitamin C : A water soluble vitamin present in citrus fruits and juices, green peppers, cabbage, spinach, broccoli, kale, cantaloupe, kiwi, and strawberries.
Beta-carotene is a precursor to vitamin A (retinol) and is present in liver, egg yolk, milk, butter, spinach, carrots, squash, broccoli, yams, tomato, cantaloupe, peaches, and grains.
Can anti oxidants help in preventing serious disease such as cancer and coronary disease?
Studies have shown lower cancer rates in people whose diets are rich in fruits and vegetables. This has lead to the theory that these diets contain substances (antioxidants) which protect against the development of cancer. So far, none of the large studies have shown that dietary supplementation with extra antioxidants reduces the risk of developing cancer.
Antioxidants are also thought to have a role in slowing the aging process and preventing heart disease and strokes. So far the data is still inconclusive. Studies are on going.
Are cells damaged due to exercise?
Endurance exercise can increase the oxygen usage 10 to 20 times more than at rest. This greatly increases the production of free radicals, causing concern of increased damage to muscles and other tissues. Athletes need to defend themselves against this free radical onslaught.
Experimental studies have taken place to look at free radical reactions and anti oxidant benefits due to exercise.
An important finding was that regular physical exercise enhances the antioxidant defense system and protects against exercise induced free radical damage. This shows that the body protects itself to a certain degree! This happens over time and with training.
Intense exercise in untrained individuals overwhelms defenses resulting in increased free radical damage. Thus, 'binge' exercising may be doing more harm than good.
Although it is well known that vitamin deficiencies can create difficulties in training and recovery, the role of antioxidant supplementation in a well nourished athlete is controversial. Most of the data suggests that increased intake of vitamin E is protective against exercise induced oxidative damage and aids in the recovery process after exercise.
In general, antioxidant supplements have not been proven to enhance performance. The one exception to this is vitamin E which has been shown to be helpful in athletes exercising at high altitudes.
Supplements or not?
Looking at all the studies on exercise and nutrition it can be deduced that if a balanced exercise regime and a diet of 5 or more servings of fruit and vegetables per day is followed, there should be no need for supplements.
'Bing' exercisers or 'weekend warriors' should develop a more balanced approach to exercise. If this isn't possible due work commitments, then supplements should be considered.
For extremely demanding races (endurance events) or adaptation to high altitude, a Vitamin E supplement should be considered up to and several weeks after the race.
