Free Radicals, Antioxidants, and Exercise

Free radicals and antioxidants are terms that gets bandied about in our progressively more health conscious culture, but they are also one of those more misunderstood things. Marketers are always taking advantage of this, touting everything from Vitamin C supplements to the latest "super food" such as acai berries.
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So today we are going to take a closer look at the science behind the hype.  What are free radicals, exactly? How are they formed? What do we need to do about them in everyday life and if we are working out or even trying to get the dream performance out of our bodies?

​Free radicals are highly unstable, chemically reactive molecules or fragments (with a free ion in the outer valence shell for those who care to hear about that). Free radicals actually exist in a variety of contexts: including environmental pollution, cigarette smoke, and some medications.

In our bodies, free radicals are formed during energy metabolism in the mitochondria (the part of our cells related to energy production) as left over nitrogen or oxygen compounds. About 2% to 5% of the time, energy metabolism creates free radicals in the form of compounds such as hydrogen peroxide and nitric oxide.

Free radicals are an issue because they can damage our DNA and fat rich membranes throughout the body. When they accumulate, they can cause what is called oxidative stress. Damage to fatty membranes is an issue because these membranes serve to isolate obnoxious toxins and carcinogens. When they are compromised, then cell constituents can become compromised too. It's also likely to mess with cell signaling pathways related to muscle atrophy and protein breakdown during longer periods of physical inactivity. Additionally, free radicals can speed cellular degeneration associated with aging along with deterioration of the central nervous system.

But don't worry: our bodies have an elaborate and effective defense against free radicals. Antioxidants such as Vitamin A, C, E, beta-carotene (a precursor of Vitamin A) and selenium play crucial roles. They combine with a set of free radical scavenging enzymes and protein binders to transform free radicals into non reactive molecule that cannot damage cells and blunt the damaging effect overall.

One of the best ways to assure that these defenses are functioning effectively is to eat a healthy, balanced diet. Checking out the USDA's and National Cancer Society's diet recommendations is an excellent start.

Dietary sources of antioxidants are also found in foods high in Vitamin C, E, and beta-carotene. Vitamin C is found in citrus, cabbage, broccoli, turnip greens, cantaloupe, tomatoes, and strawberries. Vitamin E is found in wheat germ, whole grains and cereals, leafy vegetables, vegetable oils, and dried beans. Beta-carotene is found in vegetables of every color, leafy vegetable, carrots, sweet potatoes, apricots, cantaloupe, mangos, and papaya.

Unfortunately for those who believe in vitamin and mineral supplements, the science is shifting away from declaring any long term benefits to such an approach. A series of recent studies completed in 2008 showed no health benefits to preventing cancer. One study was terminated early due to concerns of antioxidant vitamin supplements doing more harm than good. Another study showed no benefits when it came to heart attacks, angina, strokes, and a few other maladies.

How does exercise impact free radicals in our body? In the past, some scientists raised concerns that it could be detrimental due to the increase in free radicals during and following exercise. One concern here is the negative role free radicals play in muscle damage and regeneration.

There are two major ways that free radicals are produced as a result of exercise. The first is the significant changes in blood flow and oxygen supply during exercise, which result in more free radicals. The second is believed to be caused by what's called an electron leak that happens in the mitochondria within cells. The risks for these increases exist for untrained individuals in particular, and for intense exercise.

Fortunately, research has shown that free radicals are not an issue overall when it comes to exercise. It is well established that regular exercise reduces the risk of heart disease and some forms of cancer (oxidative stress is a contributing factor to cancer). Moreover, the body's normal defenses are either sufficient for the stress of exercise or the body adapts by creating more free radical fighting enzymes. And on the diet side, additional vitamins and minerals are naturally in the body due to eating more overall (assuming a healthy balanced diet).

That said, science has not found a clear answer to the question of whether additional antioxidants are needed for physically active people. If they are, then Vitamin E may be the most important antioxidant agent when it comes to exercise. The major studies around Vitamin E and recovery and free radicals recovery showed mixed results. Some studies showed a definite benefit while others did not. Differences in exercise intensity and oxidative stress may have something to do with the mixed results.

In taking a look at them myself, it appears that lower dosages of Vitamin E more regularly resulted in more benefits than higher dosages. This is in line with the with recommended Vitamin E supplementation dosages of 100 to 400 IU (international units). High dosages have been shown to cause internal bleeding, especially among those taking anticoagulant medication.

As a final note, vitamin and mineral supplementation has not been shown to help with exercise performance or training. As long as one is eating a healthy, balanced diet all the vitamins and minerals required will be present in sufficient quantities. Supplementing with more than the recommended amount won't result in any advantage, and in some cases can be detrimental.

Three groups are a little more at risk when it comes to getting sufficient vitamins and minerals. The first are vegetarians or groups like ballet dancers who strive to have low-energy intakes The second is anyone who eliminates one or more food groups from their diet. The third includes individuals who consume large quantities of processed foods or simple sugars. 

Fortunately, eating a healthy balanced diet can solve all these issues. Vegetarians and especially vegans can have a harder time with this because they will need to make sure they are getting all essential amino acids and the Vitamin B complex.

Hopefully all this serves to clear up any misconceptions around these issues. Happy Running!
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