February 18, 2014

Lactobacilli and Cyclists

Lactobacilli supplements help protect male cyclists from infections
This study adds additional support to the idea that supplementation with Lactobacilli bacteria can improve immune function and protect individuals against respiratory and intestinal infection.


West NP, Pyne DB, Cripps AW, et al. Lactobacillus fermentum (PCC®) supplementation and gastrointestinal and respiratory-tract illness symptoms: a randomised control trial in athletes. Nutr J. 2011 Apr 11;10:30.


An 11 week–long double-blinded, randomized, controlled trial


All the participants were cyclists and/or triathletes from Canberra, Australia, and its surrounding regions. All subjects on immuno-modulatory medications were excluded. Inclusion in the study was dependent on the subjects' not taking antibiotics or supplements/foods containing probiotics for at least 1 month prior to and during the study period. Subjects were also required to have a maximal oxygen uptake (VO2max) of at least 45 ml/kg/min for women and 50 ml/kg/min for men. At the start of the study there were 64 males and 35 females; age 35 ± 9 and 36 ± 9 years old. Only 88 completed the full trial and were included in the analysis.

Study Medication and Dosage

Participants were randomized into 2 groups. One group received a capsule containing 1 billion colony-forming-units of Lactobacilli fermentum VRI-003 PCC® (Probiomics Ltd, Sydney, Australia) each day. The second group received a placebo, identical in appearance.

Outcome Measures

Fecal counts of Lactobacilli fermentum, self-reported symptoms of illness, and serum cytokines were measured.

Key Findings

At the end of the trial Lactobacillus counts increased 770% in males who took the probiotic supplements (90% CI: 2.1- to 28-times baseline). There was a nonsignificant 220% average increase in bacterial count in the women who took the probiotic (0.2- to 18-times baseline count.). The number and duration of mild gastrointestinal symptoms were doubled in the probiotic group. However, there was a 70% reduction in severity of gastrointestinal illness in males at mean training load that became more pronounced as training load increased. There was a 31% decrease in severity of lower respiratory illness symptoms in the males taking probiotics (99% CI: 0.07–0.96). Surprisingly, severity of lower respiratory illness more than doubled in the women taking probiotics (CI 95%: 0.41–27). Perturbations in anti-inflammatory and pro-inflammatory cytokines in males and females taking the probiotic were ~20–75% smaller after supplementation.

Practice Implications

Although common wisdom tells us that regular exercise is beneficial, it does not acknowledge the fact that athletes get sick more often. Intensive training decreases the effectiveness of the immune system, especially decreasing mucosal immunity and increasing risk of respiratory illness and diarrhea with increasing training intensity.1,2,3 Intense training disturbs immune function, changing cytokine levels and disturbing the normal immune response to illness.4,5
This study adds additional support to the idea that supplementation with Lactobacilli bacteria can improve immune function and protect individuals against respiratory and intestinal infection.
Earlier published data have told us that supplementation with Lactobacilli can reduce the number, duration, and severity of acute diarrhea and upper-respiratory infections in the general population.6,7,8 They specifically have been shown to reduce respiratory infections in the elderly.9 While research has yielded clear indication of probiotic benefit in the general population, it has been less conclusive when studied in highly physically active cohorts. Research examining the efficacy of probiotics in physically active groups has thus far been inconclusive. Some but not all studies have shown that supplementation might be useful for endurance athletes.10,11,12,13
This study adds additional support to the idea that supplementation with Lactobacilli bacteria can improve immune function and protect individuals against respiratory and intestinal infection. Along with the other papers on immune perturbations in endurance athletes, this study suggests that we change the way we view these individuals. Rather than seeing them as super-healthy, both they and we as medical practitioners should accept that their repeated bouts of high-intensity exercise create high levels of oxidative stress that in a way leave their bodies immune-compromised.
The significantly different results seen in women versus men in this study has so far not been adequately explained. These current results would suggest that the immune perturbation in women caused by endurance exercise is more resistant to amelioration, but the difference in results between genders seen in this study needs to be substantiated before being accepted.

Categorized Under


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2. Gleeson M. Mucosal immunity and respiratory illness in elite athletes. Int J Sports Med. 2000;21(Suppl 1):S33-43.
3. Mackinnon LT. Chronic exercise training effects on immune function. Med Sci Sports Exerc. 2000;32(7 Suppl):S369-376.
4. Cox AJ, Pyne DB, Saunders PU, Callister R, Gleeson M. Cytokine responses to treadmill running in healthy and illness-prone athletes. Med Sci Sports Exerc. 2007;39(11):1918-1926.
5. Gleeson M. Mucosal immune responses and risk of respiratory illness in elite athletes. Exerc Immunol Rev. 2000;6:5-42.
6. de Vrese M, Schrezenmeir J. Probiotics, prebiotics, and synbiotics. Adv Biochem Eng Biotechnol. 2008;111:1-66.
7. de Vrese M, Winkler P, Rautenberg P, et al. Effect of Lactobacillus gasseri PA 16/8, Bifidobacterium longum SP 07/3, B. bifidum MF 20/5 on common cold episodes: a double blind, randomized, controlled trial. Clin Nutr. 2005;24(4):481-491.
8. Sazawal S, Hiremath G, Dhingra U, Malik P, Deb S, Black RE. Efficacy of probiotics in prevention of acute diarrhoea: a meta-analysis of masked, randomised, placebo-controlled trials. Lancet Infect Dis. 2006;6(6):374-382.
9. Guillemard E, Tondu F, Lacoin F, Schrezenmeir J. Consumption of a fermented dairy product containing the probiotic Lactobacillus casei DN-114001 reduces the duration of respiratory infections in the elderly in a randomised controlled trial. Br J Nutr. 2010;103(1):58-68.
10. Kekkonen RA, Vasankari TJ, Vuorimaa T, Haahtela T, Julkunen I, Korpela R. The effect of probiotics on respiratory infections and gastrointestinal symptoms during training in marathon runners. Int J Sport Nutr Exerc Metab. 2007;17(4):352-363.
11. Cox AJ, Pyne DB, Saunders PU, Fricker PA. Oral administration of the probiotic Lactobacillus fermentum VRI-003 and mucosal immunity in endurance athletes. Br J Sports Med. 2010;44(4):222-226.
12. Gleeson M, Bishop NC, Oliveira M, Tauler P. Daily probiotic's (Lactobacillus casei Shirota) reduction of infection incidence in athletes. Int J Sport Nutr Exerc Metab. 2011;21:55-64.
13. Tiollier E, Chennaoui M, Gomez-Merino D, Drogou C, Filaire E, Guezennec CY. Effect of a probiotics supplementation on respiratory infections and immune and hormonal parameters during intense military training. Mil Med. 2007;172(9):1006-1011.