Everyone knows that exercise and sports activities are good for you, but overtraining and high-performance sport may increase your risk of oxidative stress, which is associated with acute injuries, inflammation and later risk of neurodegenerative disease such as Alzheimer’s disease and ALS (amyotrophic lateral sclerosis). It is therefore a good idea to take antioxidant supplements, as this may help prevent both acute and chronic injuries. A comprehensive article published in the science journal Nutrients looks closer at the relation between free radicals and antioxidants, which have different functions in connection with various types of physical activity. This is especially the case with vitamins A, C, and E plus selenium and zinc. It is also important to make sure to get enough vitamin D and omega-3 fatty acids for counteracting inflammation and oxidative stress.
Oxidative stress is an imbalance between free radicals and antioxidants. Free radicals are aggressive molecules that attack cholesterol, cells, and DNA. They are also a natural byproduct of our cellular energy metabolism and therefore a vital part of numerous physiological processes, which means that oxidative stress occurs in smaller quantities in all humans. What increases the oxidative burden are things like intensive physical training, ageing processes, poisoning, inflammation, radiation and various stress factors.
Our only source of protection against free radicals are the different types of antioxidants, which the body is able to produce and which we get in limited amounts from the food we eat. The different antioxidants have different ways of protecting cells. This will be addressed later on
A number of diseases like atherosclerosis, neurological disorders, and even cancer are associated with oxidative stress. In these cases, the oxidative stress burden is overwhelming. Although physical training has a number of health benefits and can even counteract the harmful impact of free radicals, it is known that exaggerated training and elite sport may do the opposite and provoke oxidative stress, inflammation, muscle injuries, and nerve damage. It all boils down to what type of training you engage in, how intensive it is, the duration of the activity, and your age. The aim of the new Italian study was to look closer at how oxidative stress affects athletes’ risk of acute muscle injury and long-term neurological disease, and if antioxidant supplementation can prevent such oxidative injuries.
Different kinds of free radicals
Free radicals – also known as reactive oxygen species (ROS) – play a vital role in different physiological processes and the development of numerous diseases. ROS is a common term for various reactive oxygen compounds with one or several unpaired electrons. To compensate for the lacking electrons, the ROS snatch electrons from other molecules, causing them to become oxidized and turn into free radicals. This sets off an entire chain reaction of oxidative damage in the body. The lipids in the cell membranes and DNA plus other proteins are particularly vulnerable to this oxidative process, which can easily be compared to the rancidification of butter or rust attacking a car. ROS include such molecules as:
- Hydrogen peroxide (H202)
- Hydroxyl radicals (OH)
- Singlet oxygen (O2)
- Super oxide (O2 _)
ROS are both essential and lethal
ROS are generated inside as well as outside the body. They are primarily released from the cellular energy turnover, which takes place inside the mitochondria – the small, cellular powerhouses. ROS are a natural byproduct of our respiration, and the amount of ROS is automatically increased during intensive workouts, where the oxygen turnover in muscle cells goes up.
ROS play a role in cell growth, cell signaling and programmed cell death (apoptosis), which is when abnormal or worn-out cells self-destruct. ROS are also part of the immune system. When white blood cells (scavenger cells) are activated in order to attack bacteria or cancer cells, they take up enormous amounts of oxygen that is converted into hydrogen peroxide and super oxide, the two “killer missiles”. The process is known as the respiratory burst reaction, and because it involves the mobilization of large amounts of free radicals to fight infections, it should ideally take place swiftly and effectively. This also means that chronic inflammation is highly dangerous, as it exposes the body to a constant bombardment with free radicals.
Ageing also increases the ROS activity because the body’s oxygen utilization decreases due to failing enzyme processes. In addition, things like type 2 diabetes, environmental factors like tobacco smoke, heavy metals, medicine, toxic chemicals, UV radiation, and electromagnetic radiation add to the problem. Most carcinogens have one thing in common: They either function as free radicals or mobilize the body’s own free radical formation. Iron is also able to catalyze free radicals, which is because hydrogen peroxide combined with iron forms hydroxyl radicals that are extremely aggressive free radicals. Therefore, one should only take extra iron in very selective doses and always in combination with antioxidants.
Antioxidants from the internal environment
The different antioxidants play a vital role in the prevention of oxidative stress and the maintenance of the so-called redox balance. The essential antioxidant proteins, which the body is able to produce, work as enzymes. They are also referred to as endogenous antioxidants and include, among others:
- Superoxide dismutase (SOD) – contains zinc and manganese
- Glutathione peroxidase (GPX) – contains selenium
- Glutathione reductase (GR) – reactivates vitamins C and E
- Catalase (CAT) – breaks down hydrogen peroxide into oxygen and water
Also, there are various antioxidants that have no enzyme Q10 activity but must provide swift action, for instance:
- Q10 (ubiquinol)
- Lipoic acid
|The body’s ability to synthesize Q10, melatonin, and other antioxidants decreases with age, leaving the body more vulnerable to oxidative stress|
Antioxidants from the inner environment
Antioxidants from the inner environment are also known as exogenous antioxidants and are found in the diet. Among them are essential vitamins and minerals such as vitamins A, C, and E plus selenium, zinc, and manganese. There are also different plant compounds such as carotenoids, indoles, polyphenols, phytosterols, anthocyanins, and saponins that we get from e.g. carrots, tomatoes, red bell pepper, free-range salmon, cabbage, and other cruciferous vegetables, citrus fruits, berries, nuts, herbs, coffee, green tea, and dark chocolate.
Antioxidants from our diet affect the formation and the activity of endogenous antioxidants, thereby working in a synergy to maintain the redox balance.
The different antioxidants have the ability to:
Oxidative stress and related diseases
Oxidative stress occurs when there is an imbalance between the ROS (reactive oxygen species) and the antioxidant defense. If the oxidative stress persists, the excessive ROS accumulation affects a number of cellular signaling pathways. Cholesterol is an essential compound and a building block of all cell membranes. It is required for making stress hormones, sex hormones, vitamin D, and coenzyme Q10. Cholesterol is only harmful if free radicals oxidize it. In that case, it is consumed by white blood cells (scavenger cells) and embedded in the blood vessel walls in the form of so-called foam cells
It is the combination of this process and oxidative stress that sets the stage for atherosclerosis, regardless if your cholesterol levels are high or low.
Increased levels of ROS are also linked to cell damage and the development of neurological disorders like Alzheimer’s, Parkinson’s, Huntington’s, ALS, and sclerosis. In some of these diseases, the overproduction of ROS leads to cell damage and inflammatory processes that aggravate the problem by stepping up the ROS production additionally.
Some theories contend that in the case of cancer, the ROS destroy the mitochondria, which send distress signals to the genes, instructing them to produce energy without oxygen, by means of fermentation. In other words, cancer, to a large extent, is a metabolic disorder that is caused by oxidative stress and malfunctioning mitochondria.
ROS and physical training
During physical exercise, generous amounts of ROS are generated due to the increased respiratory rate and oxygen turnover. As mentioned earlier, ROS serve as important signaling molecules. In addition, they are able to regulate the body’s insulin sensitivity, increase glucose uptake, and increase levels of antioxidants like SOD, CAT, and Q10 in muscle cells. Therefore, it is only natural for the body to step up its antioxidant defense in connection with strenuous physical exercise.
However, if the physical training and the accumulated ROS level overwhelms the body’s antioxidant capacity, it may result in grave oxidative damage, including muscle weakness and fatigue, DNA mutations, lipid peroxidation, mitochondrial dysfunction, and cell death/apoptosis.
Many people engage in a much too ambitious program when they start running or working out at the gym, only to realize that is has consequences. Luckily, the body is able to recover from the injuries that may follow. However, once muscles or joints have been damaged, white blood cells (neutrophils and macrophages) are activated by cytokines, and the white blood cells themselves increase the production of ROS during the inflammatory processes.
The different levels of oxidative stress depend on such factors as physical intensity, the frequency and type of physical training, age, and eating habits.
In the new Italian study (mentioned in the beginning), the scientists divided the participants into the following three categories.
- Amateur athletes (1-5 hours of training per week)
- Elite athletes (more than 5 hours of training per week)
- Master athletes (more than five hours per week and older than 35 years of age)
The study results
Amateur athletes, who train on a regular basis without overdoing it, reap a number of health benefits, simply because they benefit from the positive aspects of ROS, including increased insulin sensitivity, increased glucose uptake, and increased levels of antioxidants such as SOD, CAT, GPX, GR, and Q10.
Moderate training resembles mild stress and provides the body with various health benefits, referred to in medical terms as hormesis. It keeps the cells busy and helps them perform better and adapt to the increasing demands. This also benefits the cardiovascular system, the heart, and even the mood. Elite athletes generally train more and with increased intensity. This increases the production of ROS with the risk that the antioxidant defense can longer keep up. This increases the risk of acute injuries and serious long-term damage.
Master athletes are defined as athletes from 35 years and older, who train regularly at a high level for more than five hours per week. According to the scientists, ageing in itself increases the risk of oxidative stress, but this risk is reduced if people are in good shape, as being fit increases their endogenous production of antioxidants.
After the participants had followed an eight-week moderate training program, the scientists observed that their antioxidant defense systems were allowed enough time to repair oxidative damage. This, however, was not the case with those participants, who only trained for four weeks or who trained with greater intensity.
The researchers measured levels of oxidative stress as well as the presence of harmful compounds from lipid peroxidation (TBARS), which are indirect markers of the ROS production.
Oxidative stress and muscle injuries
It is commonly known from training that aerobic combustion (with oxygen) as well as anaerobic combustion (without oxygen) can lead to oxidative damage. Training-related muscle injury typically occurs in two different phases. The first phase consists of muscle injuries that occur while training. This phase depends on several factors related to the structure of the muscle fibers. The second phase is linked to delayed inflammatory processes. Muscle fibers that have been damaged cause infiltration of white blood cells (neutrophils) that break down the damaged tissue by generating ROS. This process attracts even more white blood cells (macrophages) to the affected tissue, where they participate in the cleanup process.
During this process, muscle fibers should ideally regenerate, and if the ROS concentration is within the normal physiological range, it has a positive effect on the healing process. However, if the ROS concentration is too high, it may in extreme cases lead to chronic inflammation, necrosis, incomplete healing and the formation of fibrous scar tissue. The scientists also look into the fact that genetics play a role in terms of the muscles’ capacity and ability to regenerate.
Oxidative stress and neurological diseases
Several studies reveal that retired pro athletes have a substantially higher risk of developing neurological diseases such as Alzheimer’s and ALS. Neurological disorders are characterized by a progressive loss of neurons that impairs motor skills and cognitive skills.
Contact sports such as football, hockey, and boxing are particularly risky, especially in the case of physical traumas such ad head to head collisions or spinal cord injuries. A study of 7,325 male professional football players, who played in the Italian first and second division during the period from 1970 to 2001 showed a significantly increased risk of developing ALS.
There are other reasons why athletes may develop neurological disorders, however, including genetic factors, other causes for oxidative stress, and even substance abuse that may lead to altered brain physiology.
The researchers’ conclusion: Antioxidant supplements are affective
It remains to be answered whether it is an advantage or not to take antioxidant supplements in combination with physical training. The new article concludes that it all depends on whether or not the body’s antioxidant system is able to keep up with the ROS impact to prevent oxidative stress. If you train at a moderate physical level, the body is normally able to do so. However, with intensive physical training and elite sport, there is an increased risk of oxidative stress, and that may lead to serious, acute and chronic injury.
The scientists therefore point to antioxidant supplementation as a promising strategy for reducing oxidative tissue damage in athletes, who train vigorously.
The study data indicate that antioxidant supplementation is associated with a positive impact on different markers of oxidative stress, inflammation, and physical performance. In conclusion, better training techniques combined with a healthy diet and antioxidant supplementation may contribute to reducing muscle and joint injuries and possibly even lower the risk of developing chronic degenerative diseases like rheumatism and neurological disorders such as Alzheimer’s disease and ALS.
When choosing supplements with antioxidants such as vitamins A, C, and E plus selenium and zinc, it is vital to choose a good quality that the body is able to absorb and utilize. There are products on the market that combine these specific antioxidants and contain high-quality selenium yeast. One specific patented selenium yeast can document that it has close to 90 percent bioavailability.
Q10 supplements are also relevant when it comes to endurance sports. Also, as you grow older, Q10 is useful because the body’s endogenous production of the compound decreases. Q10 in its form as ubiquinone supports the mitochondrial energy turnover, whereas the ubiquinol form of Q10 serves as an antioxidant. The body interchanges between the two different forms of Q10. It is a compound, which the body has great difficulty with absorbing, so make sure to purchase a product that has good bioavailability and can document it.
Remember vitamin D and omega-3 fatty acids
As mentioned, inflammation plays a key role in oxidative stress, and antioxidants are able to neutralize ROS. However, we also need vitamin D and the omega-3 fatty acid EPA that has anti-inflammatory properties. Oily fish or fish oil supplements are the best source of EPA. Linseed oil and other vegetable sources contain omega-3 in the form of ALA (alpha-linolenic acid), which many people have difficulty with converting into EPA due to sluggish enzyme processes in the body.
|Athletes should pay careful attention to getting enough of the following nutrients:|
|Antioxidants||Vitamins A, C, E, zinc, selenium, Q10|
|Energy turnover||B vitamins, magnesium, selenium, zinc, Q10|
|Thyroid hormones||Iodine, selenium|
|Blood formation||B vitamins, iron (only take iron supplements if you are deficient)|
|Bones||Vitamin D, calcium, magnesium|
|Immune defense||All vitamins, especially vitamins C and D plus selenium and zinc|
|Anti-inflammatory properties||Antioxidants, vitamin D, the omega-3 fatty acid EPA|
Common flaws in the diets of athletes:
Christina Nocella et al. Impairment between Oxidant and Antioxidant Systems: Short- and Long-term Implications for Athletes´ Health. Nutrients 2019
Roma Pahwa; Ishwarial Jialal. Chronic Inflammation. NCBI April 2018
The Norwegian University of Science and Technology (NTNU). Understanding how omega-3 dampens inflammatory reactions. ScienceDaily 2017
Nancy R Rodriges et al. Nutrition and Athletic Performance. Medscape.
Sara Sig møller, Anna Melin, Åsa Tornberg og Anders Sjödin: Lav energitæthed og hormonforstyrrelser blandt kvindelige atleter. Dansk Sportsmedicin 2013. Institut for idræt og ernæring. Københavns Universitet, Lunds Universitet
Nielsen FH, Lukasi HC. Update on the relationship between magnesium and exercise. PubMed.gov
Pernille Lund. Q10 – fra helsekost til epokegørende medicin. Ny Videnskab 2014
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