Probiotics may boost immune cell function for marathon runners: RCT

Data published in the British Journal of Nutrition​ indicated that 30 days of supplementation with a combination of Bifidobacterium bifidum​ subsp. lactis​ and Lactobacillus acidophilus​ led to increases in phagocytosis in monocytes compared to placebo.

“It may shed light on the possibility of endurance athletes using probiotics to mitigate the immunosuppressive effects of strenuous exercise,” wrote researchers from the Federal University of Sao Paulo and the University of Sao Paulo.

Probiotics for sport​

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.

Study details​

For the new study, the Sao Paulo-based researchers recruited 27 male runners aged 25-45 to participate in their randomized, controlled, double-blind study. The runners were randomly assigned to receive a placebo (5 mg maltodextrin) or 10 billion CFUs of each probiotic plus 5 mg of maltodextrin for 30 days prior to running the São Paulo International Marathon. The researchers do not disclose the specific strains used in their study.

Results showed that levels of monocytes remained consistent in both groups throughout the study, but the monocytes from the probiotic group showed an increase capacity in phagocytosis after 30 days. Phagocytosis is the process whereby certain immune cells engulf other cells or particles.

“The increase in phagocytic capacity represents an improvement in the essential function of monocytes,” wrote the researchers. They added, however, that this increase in phagocytosis was not observed five days after the marathon (after ending supplementation).

“These outcomes reinforce the importance of investigating probiotics supplementation and probiotic food in the immunologic field,” stated the researchers, before calling for future studies to further explore probiotic supplementation for endurance athletes, and specifically how these beneficial microorganisms may benefits female runners.

Source: British Journal of Nutrition​
Published online ahead of print, doi: 10.1017/S0007114524001259​ 
“Thirty days of double-strain probiotic supplementation increases monocyte phagocytosis in marathon runners”
Authors: E. Tavares-Silva, et al.