What Are Probiotics, What Are They Good For, How to Use? Article Series 2

Studies on Probiotic Supplements in Athletes
Endurance or strength sports, depending on the intensity and type of performance, can increase the risk of conditions such as vomiting, abdominal pain, diarrhea, and nausea. Additionally, upper respiratory tract infections (URTI), increased risk of chronic infections, or injuries can be associated with sports activities.
Due to such discomforts, antibiotics are often prescribed to elite athletes. However, the concern arises from the routine use of antibiotics being associated with antibiotic-related side effects such as diarrhea, fatigue, tendon injuries, cardiac arrhythmias, and decreased performance. These situations prompt coaches and athletes to seek preventive measures against potential illnesses to ensure optimal performance.
Preventing illness during intense exercises and competitions is a priority for athletes and coaches. Researchers have focused on studying the effects of probiotic supplements on microbiota changes during the training period, the frequency of gastrointestinal discomfort, and respiratory tract disorders during the seasons when illness is more prevalent, such as winter and spring.
However, the specific probiotic type, dosage, or the type of physical activity where a real benefit can be observed is yet to be defined. When problem-oriented categorization is made, mechanisms of action resulting indirectly from the impact can be observed, affecting performance.
Effect of Probiotic Supplements on Immune System Diseases in Athletes
Intensive physical exercises have negative effects on the immune system. An increase in natural killer cells leads to a decrease in the functions and numbers of immune cells. This results in an increase in respiratory problems and gastrointestinal diseases, which can limit physical performance.
A study suggests that probiotic consumption may benefit athletes participating in an intense physical exercise program by strengthening immune function. West et al. (2009) reported that probiotics could indirectly prevent the immunosuppressive effects of exercise and reduce susceptibility to illness.
In a study by Cox et al. (2010), examining the effects of Lactobacillus fermentum VRI-003 on systemic immunity in endurance athletes, a decrease in the frequency and severity of respiratory infections was observed, with a twofold increase compared to the placebo group.
Effect of Probiotic Supplements on Gastrointestinal Diseases in Athletes
A review in 2009 on immunity and exercise suggested that probiotic supplements modulate intestinal flora, potentially enhancing gut and immune functions. There is significant evidence showing that probiotics reduce susceptibility to acute infections, diarrhea, and associated symptoms.
Through positive effects on the gastrointestinal system, probiotics can reduce the risk of negative symptoms during exercise, contributing to improved exercise performance. Some studies examining the effects of Lactobacillus fermentum (PCC) supplementation have shown a significant reduction in the severity of gastrointestinal symptoms in men during intense exercise. However, women experienced a higher frequency and duration of moderate gastrointestinal symptoms during the PCC supplementation period.
Effect of Probiotic Supplements on Respiratory System Diseases in Athletes
Studies indicate that certain probiotic strains increase resistance to upper respiratory tract infections (URTI), potentially preventing symptoms during exercise and competitions in the winter and spring months. Athletes in sports such as rowing, cycling, swimming, and triathlons, which involve prolonged, intense exercises, may have a higher incidence of upper respiratory tract infections.
While population studies suggest that probiotics increase resistance to upper respiratory tract infections, conclusive data from athlete-specific studies have been limited. Some studies suggest that daily probiotic supplementation may limit exercise-induced decreases in tryptophan levels and reduce the incidence of URTIs.
Studies by Gleeson et al. (2011) on physically active individuals and triathletes found that regular consumption of Lactobacillus casei Shirota reduced the incidence of URTIs but did not affect severity or duration.
Overall, studies have shown that probiotic use in athletes improves immune function, regulates immune modulation, reduces symptoms during training and competitions, and lowers the frequency of illness. Therefore, it is believed that athletes can benefit from probiotic use.
Due to the lack of a definition of the appropriate probiotic type and dosage, recommendations regarding the specific probiotic to be used and the dosage are currently unavailable. Considering the bidirectional communication between the brain and the gut and its potential impact on mood, stress responses, and sleep, probiotic supplementation should be considered as a factor that can affect all systems and influence overall performance.
Physical activity itself can directly influence the composition of gut bacteria. Butyrate, a short-chain fatty acid, is crucial for our immunity and is produced by our gut bacteria. Exercise encourages our bacteria to produce more butyrate.
A study conducted at the University of Illinois found that just six weeks of exercise could positively impact the gut microbiota. Participants were given a cardiovascular exercise program three times a week for 30-60 minutes. At the end of the study, it was discovered that the participants' gut microbiota had changed. Some experienced an increase in specific gut microbes, while others experienced a decrease. Most showed an increase in microbes playing a role in the production of beneficial short-chain fatty acids like butyrate.
After the initial six-week period, participants returned to their normal sedentary lifestyles. Researchers found that after this sedentary period, the participants' gut microbiota had returned to its state before the exercise period. This indicates that the effects of exercise on the microbiota may be short-term, emphasizing the importance of regular exercise.
In conclusion, probiotic use in athletes has been shown to enhance immune function, modulate the immune system, and reduce the frequency of symptoms during training and competitions. While specific recommendations on probiotic type and dosage are still lacking, the potential benefits of probiotic supplementation should be considered as a multifaceted factor influencing overall athletic performance.