Reviewed by Bob Seebohar MS, RD, CSCS
Director of Sports Nutrition for the University of Florida
Every athlete probably knows of antioxidants for their health benefits, but can antioxidants make an athlete faster? How do antioxidants fit into an athlete’s regimen for performance and recovery? What exactly is an antioxidant? Tending to look first at products for performance and then at recovery systems, athletes often overlook antioxidants. Crucial not only for the health of the cardiovascular system, they can also aid in performance and recovery. For many years scientists as well as consumers have known of the antioxidant powers of vitamins E & C and selenium. Today, this category has expanded to include oligomeric proanthocyanidins (OPCs), Alpha Lipoic Acid, grape skin, grape seed, beta-carotene, lutein, tocopherols, tocotrienols and various other compounds. It can certainly be confusing since so many supplements, both traditional and newly introduced, can be classified as antioxidants.
What is oxidative stress and how does it affect me? Oxidative stress is the sum of all chemical reactions giving rise to free radicals or “reactive oxygen species” (ROS) in the body. Free radicals (or ROS) are molecules containing oxygen that have unpaired electrons in the outer orbital. These unpaired electrons are what make the molecule reactive which eventually can lead to cell damage in the body. Many diseases and disorders are the result of damage to cellular components by free radicals. These free radicals can cause damage to cellular proteins, lipids, carbohydrates and DNA. The resulting stress contributes to tissue damage and eventually leads to cell death (referred to as lipid peroxidation). In addition to damage from free radicals, oxygen that simply exists within aerobic systems — like the human body — creates toxic metabolites, which in turn cause damage to cells. ROS are generated when the body is exposed to a variety of different conditions and environments (see table 1 for examples). But it’s not all bad news. Superoxide dismutase (SOD) and glutathione peroxidase, among others, are naturally occurring antioxidant enzymes which combat the effects of ROS in the body.
So then, what exactly is an antioxidant? Keep in mind that free radicals have one or more unpaired electrons that try to remove an electron from a stable molecule in order to stabilize themselves. Therefore, an antioxidant is a nutrient that offers an electron-rich binding site for these damaging free radicals, giving them a preferential site to bind to and pair up with missing electrons. So even though it seems like simple breathing is not healthy, the oxidation damage caused by the air we take in can be overcome with proper antioxidant protection. As noted above, SOD, and enzyme that occurs naturally in the body is part of our defense system against free radical damage. There are also antioxidants like Vitamin E, C and A, vitamin like compounds (glutathione, lipoic acid, bilirubin), and phytochemicals (flavonoids, polyphenols) that can play a role in our defense system when consumed in a balanced diet through foods or taken orally as dietary supplements. You probably recognize now that oxidative stress is unavoidable for humans, but of special concern to us as endurance athletes — cycling on long roads, running trails and swimming in the open water – is the greater oxygen demand, the altitude, the UV rays, inflammation, and pollution, which compound normal cell damage.
How do I best use antioxidants as an endurance athlete? Athletes who train competitively probably experience more oxidative stress than the average individual. In fact, studies have shown that endurance and strength training athletes produce more free radicals than sedentary individuals. However, it is not clear whether strenuous exercise increases the need for additional antioxidants. This oxidative stress not only causes damage to our cells and DNA, it may also limit our aerobic capacity. On the other hand, there is growing evidence that free radicals serve as signals to stimulate the adaptive processes in muscle cells. Antioxidants from food and supplementation may help maintain the integrity of cell membranes, allowing oxygen to be carried more efficiently and effectively to the working muscles. Damage to membranes may compromise the blood’s oxygen carrying capacity, negatively affecting aerobic performance. Antioxidants like vitamin C also have powerful immune enhancing properties, beneficial because intense exercise may cause a suppressed immune system in endurance athletes who are at increased risk for upper respiratory tract infections (URTI), although the data show mixed results. For example, after an intense aerobic bout you may notice phlegm and coughing that lasts a few hours or a few days. Vitamin C may help combat this suppressed immune function allowing an athlete to train at a higher level day in and day out.
ORAC=Antioxidant Quality: An analytical method developed by Dr. Cao and Dr. Ronald Priori in conjunction with the USDA Human Nutrition Research Center on Aging at Tufts University in Boston, MA and Brunswick Laboratories, Inc., Wareham, MA measures the quality of an antioxidant. ORAC=Oxygen Reactive Absorbancy Capacity is a quantitative measure of an antioxidants ability to neutralize oxygen free radicals. The clinical data supporting this methodology, though scrutinized by some has become the gold standard for the measurement of an antioxidants free radical scavenging ability. Foods that score high in an antioxidant analysis called ORAC help protect cells and their components from oxidative damage. So suggests the latest studies of animals and human blood at the Agricultural Research Service’s Human Nutrition Research Center on Aging at Tufts University in Boston. The higher a foods ORAC score, the better it is at helping our bodies fight against the damages of oxidative stress.
NEW RESEARCH (2004-2005):
Emerging evidence over the last year has indicated that fruit and vegetable consumption are directly correlated with antioxidant status. While this has been known for sometime, what is becoming more and more apparent is that some athletes are not obtaining adequate amounts of antioxidant compounds in their diet due to a low intake of fruits and vegetables.
While there is still debate among the literature regarding the efficacy of dietary supplementation of antioxidant compounds, there have been a few recent studies that are of special note.
One study compared the effects of normal antioxidant supplementation with reduced antioxidant supplementation in acute, high intensity exercise of up to 40 minutes. The reduced antioxidant group noticed a three-fold decrease in antioxidant intake and caused the athletes to have a higher rating of perceived exertion and a lower antioxidant capacity and circulating antioxidant concentrations. However, time to fatigue was not significantly different and the authors concluded that supplemental antioxidants may not be necessary for athletes engaged in less than 40 minutes of high-intensity exercise as long as an antioxidant rich eating plan was followed.
Another study examining the effects of ultrarunning (six long duration races in the desert) on antioxidant status found quite the opposite results. Blood draws before the race and 72 hours after the race showed significant decreases in erythrocyte superoxide dismutase activity and in plasma concentrations of retinol, beta-carotene and other carotenoids. This caused an imbalance between oxidant and antioxidant protection in this extreme endurance competition.
Of interesting note on the same topic was a study done that evaluated the effects of antioxidant supplementation (vitamins C, E and beta-carotene) on the basal iron status of athletes prior to and following their training and competition season, which lasted for 3 months. Not surprisingly, they found that training decreased antioxidant defenses in the athletes who were not taking antioxidants; however, of particular interest is that they also found decreases in serum iron and iron saturation in these same athletes. This may indicate that antioxidant supplementation may prevent the decrease of iron stores and that a link between iron status and oxidative stress could exist.
Recommendations: It is estimated that only 10% of the U.S. population consumes five servings of fruits and vegetables per day. Due to the nature of aerobic training, endurance athletes may need further protection from the damage of oxidative stress. Some of the newest clinical research suggests that this oxidative protection may even lead to improved performance. With abundant formulas and antioxidant concoctions in the marketplace, don’t rely on a single compound. Look for a formula or multi-vitamin that contains a variety of antioxidants. If you are shopping for antioxidant supplements the majority of research focuses on vitamins C & E, Selenium and Beta-Carotene. Also consider the following in your search for an appropriate formula: Alpha Lipoic acid, grape seed extract, carotenoids, pycnogenol, lutein, lycopene, Bioflavanoids, green tea, turmeric and quercetin. In some newer formulas you can also specifically find antioxidants which have been analyzed for their ORAC value.
Even though it’s easier to take a handful of supplements, a healthy diet should be the basis of your antioxidant defense system: brightly colored fruits and vegetables along with certain grains, seeds, and nuts provide excellent sources of antioxidants to protect your cells from unwanted oxidative damage. As an athlete, your best bet is to eat fresh, whole foods so you’re not relying solely on supplements for antioxidants. Look at the table below for options to increase the color and antioxidant power in your diet.
The damaging effects of oxidation can take years, even a lifetime to reveal their impact. Antioxidants should be viewed as insurance against this damage. With long-term consumption of antioxidants you will support healthy cells leading to healthy cellular respiration. If you train heavily day in and day out, antioxidants should be a staple in your training diet. Within a few months of increased consumption you should notice reduced incidence of infection, faster recovery and better workouts.
Taking into consideration all of the newest research on antioxidants and athletes, there appears to be a few take home messages:
1. Athletes typically do not eat enough fruits and vegetables to obtain adequate amounts of antioxidants.
2. Antioxidant supplementation may not be needed in short duration, high-intensity exercise.
3. In ultra-endurance events, oxidative stress is high and antioxidant levels are compromised.
4. There may be an association between iron status and oxidative stress but there is not enough data to make any conclusions.
Overall, the take home message of increasing fruit and vegetable intake to a minimum of 6-9 servings per day is still valid and will supply the athlete with a good amount of vitamins, minerals and antioxidants. However, if the athlete is competing in longer duration events, antioxidants may become more efficacious and therefore the athlete should pay closer attention to their overall eating and supplementation program.
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