Daily ingestion of fermented milk containing 40 billion live cells of L. casei Shirota (LcS) for 30 days before a marathon led to reductions in several proinflammatory cytokines, and increases in anti-inflammatory responses in the upper respiratory tract.
“Taken together, our results showed, for the first time, that the previous 30 days daily ingestion of fermented milk containing 40 billion of LcS was able to modulate both immunological and inflammatory responses in the blood and also in the upper airways mucosal of amateurs´ runners after a marathon, presenting protective effects,” wrote scientists from the Federal University of São Paulo (UNIFESP) and Cruzeiro of Sul University in Nutrients.
The gut microbiota and athletes
The link between gut health and athletic performance has been garnering increasing attention from scientists. Strenuous or excessive exercise is known to suppress the host immune system, which has led to studies finding that gut microbiome modification may help reduce the incidence of upper respiratory tract infections in endurance athletes.
The potential to enhance athletic performance has also been explored, with scientists at University College Cork in Ireland reporting in 2014 that the gut microbiomes of professional Irish rugby players were significantly more diverse than non-athletes. In addition, the researchers found that the rugby players had higher proportions of Akkermansia, compared to non-athletes with high BMI. Akkermansia has been linked to improved metabolic profiles and is reported to have anti-obesity effects.
A follow-on study performed in collaboration with scientists at Imperial College London in England (and also published earlier this year in Gut) found the differences between athletes and sedentary people is “even more evident at the functional or metabolic level”.
The new study from Brazil is said to be the first to assess the effects of L. casei Shirota strain to impact immune and inflammatory profiles in amateur marathon runners.
Forty-two male marathon runners were randomly assigned to consume either fermented milk containing 40 billion of LcS/day or a placebo unfermented milk for 30 days before running a marathon.
The data indicated that men in the placebo group had higher levels of proinflammatory cytokines in serum and the nasal mucosa immediately post-marathon, compared to other time points and to the probiotic group.
Men in the placebo group also had lower levels of salivary Secretory immunoglobulin A (SIgA) and antimicrobial peptides, said the researchers.
“SIgA is considered as the “first line of defense” against mucosal pathogens, and there is a consensus that reduced salivary SIgA levels are associated with an increased risk of developing URS [upper respiratory symptoms] after an exhaustive physical exercise session or even during periods of intense exercise training,” they explained. “Here, lower salivary SIgA levels were found immediately post-marathon only in the placebo group.
“Although we did not observe increase in SIgA in LcS group, the maintenance of it levels can contribute to the upper airways protection against pathogens and consequently minimizing the incidence and duration of URS, as already mentioned.”
In addition, the probiotic group had higher anti-inflammatory levels and reduced neutrophil infiltration on nasal mucosa compared to other time points and to the placebo group.
“[T]hese remarkable results showed that the daily ingestion of fermented milk containing LcS can maintain the immune protection in the upper airway mucosal and minimize both the incidence and duration of URS after a marathon, as observed by us,” concluded the researchers.
2019, 11(7), 1678; doi: 10.3390/nu11071678
“Daily Intake of Fermented Milk Containing Lactobacillus casei Shirota (Lcs) Modulates Systemic and Upper Airways Immune/Inflammatory Responses in Marathon Runners”
Authors: M. Vaisberg et al.