The athlete and the immune system

"The Incidence of Immuno Supression in Athletes and a Review of Nutrients that can Boost the Efficiency of the Immune System"

The health of an athlete is of the utmost importance to ensure not only the maximum level of performance in competition but that their training regime is consistent in order to further progress their performance through:

• improved fitness
• motor skills
• recovery
• and other factors that will benefit their particular sport

It is, however, a sad reality that many athletes partake in extensive training programs without enough thought for their actual health status. We should consider the importance of the immune system, and the fact that excessive training can lead to a suppression of its efficiency. This in turn can lead to illness that can hinder both training and competitive performance.

I will give suggestions, with supportive evidence, as to nutrients to help support the efficiency of the immune system. All of the nutrients cited may be taken as dietary supplements but this is not meant to infer that regular, healthy food is not vital for the good health of the athlete. In fact there are many benefits to natural, high-vitality foods that are still being discovered and explored, such as the role of phyto-nutrients as potent anti-oxidants - which again are vital for the good health of anyone partaking in an exercise program.

The health benefits of regular exercise are numerous - including

• increased cardio-vascular fitness
• lowered cholesterol levels
• increased metabolic rate
• greater muscle strength
• and lower incidence of osteoporosis among others.

• Light to moderate exercise, carried out on a regular basis has actually been seen to have a positive effect on the efficiency of the immune system.
• Excessive exercise, high in either duration, regularity or intensity, has been found to be immuno-suppressive. Yet the reality is that any seriously competitive athlete must put the hours into his/her training programs in order to achieve the level of fitness and technical skill required to win.

The intensity and frequency of such programs leaves us open to many of the opportunistic infections that we would normally kill off quite easily. Instead they can take hold and proliferate, and the most common that are seen in athletes are "upper respiratory tract infections". This term encompasses virus's that affect the throat, chest, nose, and ears.

It is, therefore, important that the athlete does not overreach his physiological limitations when formulating his/her training regime. If the training, and nutrition, can be matched to the needs and physiological efficiency of the athlete then the immune system will react to the trauma of exercise by improving in its efficiency to fight infection.

Exercise And The Increased Incidence Of Upper Respiratory Tract Infections:

As previously stated one of the most common ailments seen in athletes is the incidence of upper respiratory tract infections, this is a broad heading for a number of similar complaints. Many manifest themselves as colds, sore throats, chest infections and other related ailments. These are by no means the only side effects of a suppressed immune system but they do tend to manifest themselves noticeably in the period immediately following competition, especially with endurance events. These ailments, whilst often minor, can be frequent depending on the athletes training/competition schedule and this can interfere greatly with their progression.

The risk of immuno-suppression, and thus the increased risk of an associated ailment, seems to relate to several training factors that include:

• duration
• frequency
• and intensity

If these factors are controlled and adjusted to the individual athlete the outcome can be very different.

Evidence is not conclusive as to the cause of URTI's but likely contributory factors include:

• high ventilatory rates that adversely affect the mucosal surfaces of the upper respiratory tract
• depletion of various nutrients that play a positive role in the function of the immune system such as glutamine and vitamin C
• and disruption of hormone regulation due to psychological stress factors associate with training and competition.

Athletes are possibly more likely to comply with a nutritional program than a reduction in training intensity and frequency as they may feel that such a reduction, so as to alleviate depletion factors and the chances of overtraining, would be detrimental to the development of their performance.

Here are examples of Nutrients That Can Increase The Efficiency Of The Immune System:

 Glutamine

Glutamine is:

• the most common free amino acid found in your body.
• It is the major source of energy for your immune system and your digestive system.
• It is a common neurotransmitter in the brain
• and it is a precursor for other neurotransmitters
• It is used to synthesize DNA
• and it has a variety of other functions.

  In times of shortage, the body will catabolise muscle tissue to create glutamine. Therefore, a glutamine deficiency could cause a variety of problems. The body can make glutamine from other amino acids. However, in times of severe illness and severe injury, glutamine stores become depleted.

Supplementing

Supplementing with glutamine then has major positive effects, avoiding the catabolism of muscle protein and boosting the immune system being the effects of most importance to athletes.

• A short-term deficit occurs - after a strenuous exercise bout
• while a chronic deficit occurs - in the overtraining syndrome

Exercise such as long distance running places several stresses on glutamine.

• Firstly running does cause damage. For example, muscles can get micro-tears. Repairing your muscles, including building them up, requires glutamine. This causes an increased demand in the days following a strenuous run.
• Secondly, when glucose is used incompletely for energy, the byproducts are lactic acid and hydrogen ions. The body has to remove these hydrogen ions. It uses glutamine to do this.
• Thirdly, glutamine is used to synthesise a powerful antioxidant called glutathione. The increased free radicals of oxygen caused by running create a need for more glutathione, which in turn causes more need for glutamine. Glutamine is used to support and maintain glutathione. Athletes have been observed to be deficient in glutathione, in one study 90 minutes of exercise led to a 60% reduction in glutathione.

  All of these demands on glutamine occur in addition to the ongoing need for glutamine by the immune system, the digestive system, and the brain. Glutamine levels in the blood sometimes increase during exercise. This reflects the increased demand for glutamine, with the glutamine in the blood coming from stores in the muscles. Later, the blood levels of glutamine drop. A 20% reduction in plasma glutamine has been observed in runners 1 hour after a marathon. In another study, plasma levels of glutamine were decreased 40% by a training session at 90% of VO2max. It takes several hours to return to the pre-exercise levels of glutamine.

Deficiency

For several reasons, a glutamine deficiency would impair recovery from training. The body has some free sources of glutamine, such as the free glutamine in the muscles. When these sources run out, the body catabolises muscle to make more glutamine. Glutamine is needed to build cells. Even if there is not enough deficiency for muscle catabolism, there might be enough of a deficiency that your muscles are not repaired from the damages of training.

Glutamine is the major energy source for the immune system. It is critical for the functioning of the antibody-producing lymphocytes and has been shown to enhance the neutrophils ability to engulf and destroy bacteria. This is in addition to the general boosting effect on the natural killer cells that are our first line of defense against other invaders such as viruses. The body will try to catabolise muscle in order to have enough glutamine for your immune system. Nonetheless, there is evidence that the glutamine deficiency in athletes impairs immune function.

Overtraining Syndrome

Finally, there is powerful evidence for the role of glutamine in the overtraining syndrome. It was observed in a study of 10 athletes that were seriously into an overtraining state where a number of factors that were suspected to be associated with overtraining were measured. Only one was actually associated with overtraining - glutamine. For 9 of the 10 overtrained athletes, their glutamine levels were below the normal range for athletes, and the tenth athlete recovered from overtraining fairly quickly. Many of the symptoms of overtraining match the potential consequences of a glutamine deficiency. Some symptoms of overtraining are:

• worsening performance
• increasing sickness
• and digestive problems, especially diarrhea.

  A glutamine deficiency could produce all of these. Digestive problems could lead to deficiencies in other nutrients, creating other problems. Another symptom is increased chance of injury. Glutamine could produce this by decreasing the rebuilding of tissue and by reducing glucosamine. Two of the mental symptoms of overtraining are lethargy and perhaps even mental confusion. This would be the flip side of the increased energy and mental alertness produced by glutamine. It is suggested that 5 grams per day might compensate for the glutamine deficiency in the average overtrained athlete.

 Vitamin C

Vitamin C is one of the most popular selling supplements in the western world, and most of its popularity is due to the extensive research and application of this nutrient in the role of the immune system.

Functions

The functions of vitamin C within the body are many and they include the manufacture of collagen, which is the main protein substance of the human body. This collagen is a vital protein for the structure of connective tissue, cartilage and tendons; it is also required for wound repair and the prevention of easy bruising. In addition to its structural uses it is also a very important nutritional antioxidant. In fact it is the first line of antioxidant defense in the body, and works in conjunction with vitamin E, the carotene's, glutathione peroxidase and superoxide dismutase. It is responsible for regenerating oxidised vitamin E in the body, thus potentiating the antioxidant benefits of this synergistic nutrient. As such the role of vitamin C in athletes far exceed those of merely enhancing the immune system.

Vitamin C and the common cold

In the role of an immune boosting nutrient many of the positive studies have been carried out with regard to the prevention and treatment of the common cold. Many people have made claims about the role of vitamin C in enhancing the immune system,
particularly with regard to the prevention and treatment of the common cold. However, despite numerous positive clinical and experimental studies, for some reason this effect is still hotly debated.

Immunity role

From a biochemical viewpoint, there is considerable evidence that vitamin C plays a vital role in many immune mechanisms. Infection rapidly depletes the normally high concentration of vitamin C in white blood cells, particularly lymphocytes, and a relative vitamin C deficiency may ensue if vitamin C is not regularly replenished.

Vitamin C affects various immune functions by enhancing white blood cell function and activity and increasing interferon levels, antibody responses, antibody levels, and secretion of thymic hormones. Vitamin C also possesses many biochemical effects similar to interferon, the body's natural antiviral and anticancer compound. During times of chemical, emotional, psychological, or physiological stress, the urinary system excretes vitamin C at a significantly increased rate, thereby elevating the body's need for vitamin C during these times.

Examples of chemical stressors include cigarette smoke, pollutants, and allergens. Extra vitamin C, in the form of supplementation or increased intake of vitamin C-rich foods, is often recommended to keep the immune system working efficiently during times of stress. Exercise is also a stressor to the body and as such is known to deplete levels of vitamin C in tissues. In certain instances, vitamin C supplementation is the only way to meet the concentrations needed for many health conditions.

 Zinc

Zinc is a mineral that can be found in every cell in the human body and is a component in over 200 different enzymes. It is necessary for the action of many hormones, including thymic hormones, insulin, growth hormone and sex hormones. It is stored primarily in muscle and is also highly concentrated in red and white blood cells.

Zinc deficiency can result in recurrent infections as a result of impaired immune function. A survey, carried out by the Ministry of Agriculture, Fisheries and Food, showed that the British population had a 49% deficit of the Recommended Daily Allowance of this vital nutrient. Adequate tissue levels are necessary for proper immune system function and zinc deficiency results in an increased susceptibility to infection, especially if the efficiency is further suppressed by excessive exercise.

The role of zinc in the function of the immune system is multi-factoral. When zinc levels are low the number of T cells decreases, thymic hormone levels are lower, and many white blood cell functions that are critical to the immune response cease. Fortunately all of these effects are reversible upon adequate zinc administration. Zinc, like vitamin C, also possesses direct antiviral activity including antiviral activity against several viruses that cause the common cold. Throat lozenges containing zinc are now extremely popular in the treatment of the common cold.

The use of zinc supplementation, particularly as a lozenge, is valuable during a cold and other upper respiratory tract infections both for its general immune boosting properties and its direct action upon the area of infection - namely the throat.

 

 Vitamin E

Vitamin E is very important to immune function. In addition to protecting the thymus gland and circulating white blood cells from damage vitamin E is particularly important in protecting the immune system from damage during times of oxidative stress, such as exercise, and from chronic viral illnesses. As already stated there is a strong interaction with vitamin C in that vitamin C actually regenerates oxidised vitamin E in the body and potentiates its antioxidant benefits. The vitamin E content of lymphocytes andneutrophils is 10-20 times that of red blood cells, with its main purpose being to prevent lipid peroxidation in cell membranes, which is the damage caused by free radicals. This damage can occur in lymphocyte cells if a person is deficient in vitamin E, whereas increasing vitamin E status corrects this problem.

From the evidence cited, and the vast quantity of studies to confirm the hypothesis, it is concluded that excessive exercise does in-fact suppress the immune system. Yet it is also seen that regular, and subject matched, exercise programs can increase immune function. Due to biochemical individuality, as well as many other variables including an athletes fitness levels and nutritional status, it would be impossible to set a regime that was universal in enhancing the immune system in all individuals to the same degree.

What is clear is that nutritional status plays a vital role, not only in the general health of the athlete and their performance but also in their ability to fight infection in times of stress, be it physical or emotional. As the demands on the athlete increase, especially at competition time when training generally becomes more frequent and intense, so does their requirement for immune boosting supplements. There have not been adequate studies done in this area, especially on the synergistic effect that these nutrients can elicit. The nutrients examined are by no means the only ones that can be of benefit, they have merely been selected as they are widely available and they have been studied fairly extensively. It is interesting to note that all of the cited nutrients also elicit a strong antioxidant effect, and it is known that exercise increases oxidative damage to cells and as such the inclusion of these nutrients should be important to every hard training athlete for there profound health benefits.Due to the fact that there is a lack of evidence, from scientific studies, on the synergistic effect of nutrient interaction with regards to immune-boosting supplements it would be difficult to give recommendations as to dosages.

While there are recommended minimal amounts set by authorities in each individual country, such as the Recommended Nutrient Intake in Great Britain, it is obvious that these levels will not ensure maximum efficiency of a person's immune system. This would be especially true for anyone who undertakes an exercise program, and as the demands of training rise so should the intake of many vital nutrients - some of which have been cited here.
The interrelation of the body's complex systems also needs to be addressed in more detail, specifically the inter-action of the centralnervous, endocrine and immune systems. It has been suggested that it is this complex amalgamation of systems, referred to as the psycho-nuero-endocrine-immune system, which may hold the answers that as yet have not been discovered.