title: Lactobacillus fermentum (PCC®) supplementation and gastrointestinal and respiratory-tract illness symptoms: a randomised control trial in athletes.
abstract: BACKGROUND
  Probiotics purportedly reduce symptoms of gastrointestinal and upper respiratory-tract illness by modulating commensal microflora. Preventing and reducing symptoms of respiratory and gastrointestinal illness are the primary reason that dietary supplementation with probiotics are becoming increasingly popular with healthy active individuals. There is a paucity of data regarding the effectiveness of probiotics in this cohort. The aim of this study was to evaluate the effectiveness of a probiotic on faecal microbiology, self-reported illness symptoms and immunity in healthy well trained individuals.
  
  
  METHODS
  Competitive cyclists (64 males and 35 females; age 35 ± 9 and 36 ± 9 y, VO2max 56 ± 6 and 52 ± 6 ml.kg-1.min-1, mean ± SD) were randomised to either probiotic (minimum 1 × 109 Lactobacillus fermentum (PCC®) per day) or placebo treatment for 11 weeks in a double-blind, randomised, controlled trial. The outcome measures were faecal L. fermentum counts, self-reported symptoms of illness and serum cytokines.
  
  
  RESULTS
  Lactobacillus numbers increased 7.7-fold (90% confidence limits 2.1- to 28-fold) more in males on the probiotic, while there was an unclear 2.2-fold (0.2- to 18-fold) increase in females taking the probiotic. The number and duration of mild gastrointestinal symptoms were ~2-fold greater in the probiotic group. However, there was a substantial 0.7 (0.2 to 1.2) of a scale step reduction in the severity of gastrointestinal illness at the mean training load in males, which became more pronounced as training load increased. The load (duration×severity) of lower respiratory illness symptoms was less by a factor of 0.31 (99%CI; 0.07 to 0.96) in males taking the probiotic compared with placebo but increased by a factor of 2.2 (0.41 to 27) in females. Differences in use of cold and flu medication mirrored these symptoms. The observed effects on URTI had too much uncertainty for a decisive outcome. There were clear reductions in the magnitude of acute exercise-induced changes in some cytokines.
  
  
  CONCLUSIONS
  L. fermentum may be a useful nutritional adjunct for healthy exercising males. However, uncertainty in the effects of supplementation on URTI and on symptoms in females needs to be resolved.
  
  
  BACKGROUND
  The trial was registered in the Australia and New Zealand Clinical Trials Registry (ACTRN12611000006943).
authors.affiliation: Griffith Health Institute, Griffith University, Australia.
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: West
authors.forename: David B
authors.initials: DB
authors.lastname: Pyne
authors.forename: Allan W
authors.initials: AW
authors.lastname: Cripps
authors.forename: William G
authors.initials: WG
authors.lastname: Hopkins
authors.forename: Dorte C
authors.initials: DC
authors.lastname: Eskesen
authors.forename: Ashok
authors.initials: A
authors.lastname: Jairath
authors.forename: Claus T
authors.initials: CT
authors.lastname: Christophersen
authors.forename: Michael A
authors.initials: MA
authors.lastname: Conlon
authors.forename: Peter A
authors.initials: PA
authors.lastname: Fricker
mesh_terms: D000328:Adult; D056352:Athletes; D016207:Cytokines / Q000378:metabolism; D004311:Double-Blind Method; D015444:Exercise; D005243:Feces / Q000382:microbiology; D005260:Female; D005767:Gastrointestinal Diseases / Q000382:microbiology* / Q000517:prevention & control; D041981:Gastrointestinal Tract / Q000382:microbiology; D006801:Humans; D007109:Immunity; D052197:Limosilactobacillus fermentum; D008297:Male; D008875:Middle Aged; D009520:New Zealand; D019936:Probiotics / Q000008:administration & dosage*; D012141:Respiratory Tract Infections / Q000382:microbiology* / Q000517:prevention & control; D057566:Self Report; D055815:Young Adult
chemical_list: D016207:Cytokines