Writing in Nutrients, researchers from the Federal University of São Paulo and the University of São Paulo report that for the week after the race 100% of the runners in the placebo group presented at least one URTI symptom, compared to only 71% in the probiotic group.
“The results showed that supplementation of multi-strain probiotics consisting of 1 billion CFU Lactobacillus acidophilus-LB-G80, 1 billion CFU Lactobacillus paracasei-LPc-G110, 1 billion CFU Lactococcus subp. lactis-LLL-G25, 1 billion CFU Bifidobacterium animalis subp. lactis-BL-G101, and 1 billion CFU Bifidobacterium bifidum-BB-G90 […] for thirty days was able to modulate the production of cytokines by monocytes at different times and significantly decrease the incidence and severity of symptoms in the upper respiratory tracts of athletes exposed to a marathon race,” they wrote.
Confirming prior findings
Excessive exercise like training for and running marathons is known to be a physical stressor that has been shown to reduce key immune system components such as natural killer cells, neutrophils, T and B cells. Multiple studies have shown how people training for marathons or ultra-marathons are at an increased risk of upper respiratory tract infections (URTIs), for example.
Probiotics have been studied for their immune supporting benefits for athletes and non-athletes. An international collaboration of sports nutrition experts worked together on the International Society of Sports Nutrition’s position paper on probiotics, and concluded: “Immune depression in athletes worsens with excessive training load, psychological stress, disturbed sleep, and environmental extremes, all of which can contribute to an increased risk of respiratory tract infections.
“In certain situations, including exposure to crowds, foreign travel and poor hygiene at home, and training or competition venues, athletes’ exposure to pathogens may be elevated leading to increased rates of infections.
“Approximately 70% of the immune system is located in the gut and probiotic supplementation has been shown to promote a healthy immune response. In an athletic population, specific probiotic strains can reduce the number of episodes, severity and duration of upper respiratory tract infections.”
Specific strains were highlighted by the authors for which there is human clinical data supporting a reduction in severity or duration of URTIs for endurance athletes, including Bifidobacterium animalis ssp. lactis Bl-04, Limosilactobacillus fermentum VRI-003 (PCC) (formerly Lactobacillus fermentum), Lacticaseibacillus casei Shirota (the ‘Yakult’ strain, formerly Lactobacillus casei Shirota), Lactobacillus helveticus Lafti L10.
Lead author on the ISSN position paper was Dr Ralf Jaeger, Managing Member of Wisconsin-based Increnovo LLC. Commenting on the new study, Dr Jaeger told NutraIngredients-USA: “The new study using a multi-strain probiotic confirms prior findings that probiotic supplementation can improve immune health in athletes, reducing the episodes, severity or duration of exercise-induced infections.”
The new study included 14 healthy male marathon runners who were randomly assigned to the probiotic combination or placebo for 30 days prior to a marathon. The researchers measured plasma cytokines, salivary parameters, glucose, and glutamine at the start of the study, 24 hours before the race, immediately after the race, and again one hour after the race.
In addition, the runners were asked to self-report URTI symptoms using the Wisconsin Upper Respiratory Symptom Survey (WURSS—21).
However, the researchers did not sample the intestinal microbiota of the athletes for any changes that may have occurred in response to the probiotic intervention.
Results showed that, compared to placebo, URTI symptoms were 29% lower in the runners taking the probiotic supplement.
The researchers did find differences between the groups for various plasma cytokines one day before the race and after the race.
“Considering the data obtained through different tests, and despite the low number of cases analyzed, we suggest that probiotic supplementation could effectively attenuate the symptoms and severity of minor infections in the upper respiratory tract of marathon athletes by preserving immune response and cell functionality,” they wrote.
“Probiotic supplementation is an efficient, easy to apply, and effective strategy to mitigate the deleterious effects caused by strenuous exercises on the immune system.”
2021, 13(5), 1478; doi: 10.3390/nu13051478
“Effect of Multi-Strain Probiotic Supplementation on URTI Symptoms and Cytokine Production by Monocytes after a Marathon Race: A Randomized, Double-Blind, Placebo Study”
Authors: E. Tavares-Silva et al.