Athletes and sports people, particularly the elite and endurance athletes have an increased risk of infection due to their increased exposure to pathogens, and the effects on their immune system from their lifestyle and activity (e.g. physiological, psychological and/or environmental stress, poor diet and/or sleep.
Research in this field has been conducted with L.casei Shirota, investigating reduction of colds and gastrointestinal discomfort, and reduction of ammonia levels generated during exercise.
Study: Athletes - ammonia
Modulation of ammonia metabolism - Fuskevag et al. (2012) Int J Probiotics & Prebiotics 7(1):13-16
Method: An open-label, pilot, proof of principle study was conducted in 20 male football players assigned to consume either L.casei Shirota (1.3x1010 CFU) or no supplementation daily for one month. The players undertook an exhaustive routine designed to exercise all the major muscle blocks (two cycles of a 9-station static exercise program with a one-minute rest between the two cycles; water supplied ad libertum). The players provided a four-hour timed urine sample after the exercise program. Both the exercise program and urine sampling were repeated after one month. Urine samples were measured for phenyacetylglutamine and ammonia and corrected by creatinine levels.
Results: The results (expressed as the difference in urinary levels for each volunteer between the two sampling points) showed that phenylacetylglutamine significantly increased in the probiotic group (2.98 ±1.04 vs -0.911 ±0.477; p<0.01) and, while not reaching statistical significance, their ammonia levels were also lower compared to the control group (0.953 ± 0.868 vs 1.486 ± 0.865; p=0.064).
Conclusion: The researchers concluded that probiotic supplementation with a probiotic Lactobacillus strain appeared to help regulate exercise-generated ammonia in young health sportsmen.
Study: Athletes - URTI
Reduction in upper respiratory tract infections - Gleeson et al. (2011) J Sport Nutr Exercise Metab 21:55-64
A randomised, placebo-controlled trial conducted in the UK found that regular ingestion of L. casei Shirota over the winter period appeared to reduce the mean number of upper respiratory tract infections in athletes, compared to placebo (1.2±1.0 vs. 2.1±1.2, P<0.01) and this was attributed to the maintenance of salivary IgA levels (an indicator of mucosal immune status) in the probiotic group.