Getting regular exercise is great! But as it turns out, the stress and exertion associated with frequent exercise may leave athletes more susceptible to catching upper respiratory infections (like the common cold)1. According to one recent study, probiotics may be able to provide fitness enthusiasts with some relief…

Armed with the knowledge that athletes had been found to be at a greater risk for contracting upper respiratory infections, researchers at the University of Florida turned to Lactobacillus helveticus Lafti L10 (a patented strain of the ever-popular and heavily researched lactobacillus variety) and some previously unpublished research to see if, when administered orally, the bacteria would elicit an a positive immune response from the gut and help prevent the onset of exercise-induced upper respiratory tract infections (URTIs).

Are probiotics the key to helping athletes fight frequent infections?

Before we take a look at what the researchers found, it might be useful to understand what made them start looking in the first place.

How does exercise make athletes more susceptible to infections in the first place?

relationship between activity and URTIs

Figure 1: A graph demonstrating the “J” shaped relationship that’s been suggested to exist between URTIs and exercise. Source: Natural Products INSIDER

Great question! According to one recent study, the relationship between the rate of contracting URTIs and exercise is “J” shaped (see Figure 1). The study was able to demonstrate that those who partook in moderate exercise may actually lower their risk of contracting URTIs, but for those who went beyond moderate exercise and pushed themselves closer to the realm of “over-training,” risk of contracting a URTI was found to increase considerably.2

The results demonstrated by this study happen to line up near perfectly with a commonly recognized phenomenon within the world of exercise science and sports nutrition, the “window of immunosuppression.” In the hours following intense exercise, research has found that the body is considerably more susceptible to incoming pathogens and infections.3

What did our probiotic researchers find?

While the administration of the probiotics was not able to prevent infections (overall, occurrence rates remained the same), they were able to record a significant decrease in the severity of the symptoms as well as a noteworthy decrease in the total number of days that participants were sick.

Along with these findings, the researchers also suggested in their analysis that when it comes to using lactobacillus for this particular application, the specific strain being used may make all the difference (for additional evidence, they cited several other studies that, though they had featured a strain of lactobacillus, they had been unable to demonstrate the results that had been found in this study when using L. helveticus Lafti L10). While it certainly is an interesting suggestion, there’s a need for additional research.

Potential Opportunities for Probiotics in the World of Sports Nutrition

As of now, the possibilities for incorporating probiotics into sports nutrition are near endless! In the future, it may be more than possible to provide athletes with the nutrients they want before and after their workout while also providing them with the immune boost that their body might need.


  1. Nieman DC. “Immunonutrition support for athletes.” Nutr Rev. 2008 Jun;66(6):310-20. DOI: 10.1111/j.1753-4887.2008.00038.x.
  2. Walsh NP, Gleeson M, Shephard RJ, Gleeson M, et al. Position Statement. Part one: Immune function and exercise. Exercise Immunology Review. 2011;17:6-63
  3. Nieman DC. “Immunonutrition support for athletes.” Nutr Rev. 2008 Jun;66(6):310-20. DOI: 10.1111/j.1753-4887.2008.00038.x.