Effect of Probiotics on Respiratory Tract Infections

Effect of Probiotics on Respiratory Tract Infections


Update on Probiotics for Respiratory Tract Infections

When I first wrote this post, a study at the time had equivocal results on whether or not probiotics were effective for preventing acute respiratory infections.

With the passage of time, new study data has become available. Specifically a recent Cochran review highlights the data from 10 randomized controlled trials including 3451 participants.

What Are Upper Respiratory Tract Infections?

To start with, acute respiratory tract infections include the common cold as well as inflammation of the trachea and larynx with symptoms including fever, cough, and headaches.

Most URTIs are caused by viruses and have a duration of symptoms of 3 to 7 days.

Common preparations of probiotics include bifedobacteria as well as lactic acid bacteria.  Typically, these are consumed as either dietary supplements or found in fermented foods such as yogurt.

Cochrane Review for Probiotics in Preventing Upper Respiratory Tract Infections:

Though they concluded that the evidence was weak, the authors of the Cochrane review did acknowledge that probiotics showed a benefit in preventing URTIs (Hao Q et al, 2011).  They did not find that probiotic use reduced the actual duration of URTIs though.

Author’s Conclusions:

“Current available evidence shows that probiotics are better than placebo in reducing the number of participants who experience episodes of acute upper respiratory tract infection (URTI), the rate ratio of episodes of acute URTI and reducing antibiotic use, although there were no data concerning older people in the review. However, the review indicates that probiotics may be more beneficial than placebo for preventing acute URTIs.”

Below is the previous article that I wrote back in 2007:

Effect of Probiotics on URTI’s and Gastrointestinal Symptoms

A recent study published in the International Journal of Sports Nutrition and Exercise Metabolism explored the effects of probiotics on upper respiratory tract infections and gastrointestinal symptom episodes.  Though probiotics are quickly becoming one of the most popular dietary supplements, do they work to reduce the severity of either upper respiratory tract infections or gastrointestinal infections?

Study background:

“Heavy exercise is associated with an increased risk of upper respiratory tract infections. Strenuous exercise also causes gastrointestinal (GI) symptoms. In previous studies probiotics have reduced respiratory tract infections and GI symptoms in general populations including children, adults, and the elderly. These questions have not been studied in athletes before.”

Study design:

“Marathon runners (N = 141) were recruited for a randomized, double-blind intervention study during which they received Lactobacillus rhamnosus GG (LGG) or placebo for a 3-mo training period.”

Study results:

“The duration of GI-symptom episodes in the LGG group was 2.9 vs. 4.3 d in the placebo group during the training period (P = 0.35) and 1.0 vs. 2.3 d, respectively, during the 2 wk after the marathon (P = 0.046). LGG had no effect on the incidence of respiratory infections or GI-symptom episodes in marathon runners, but it seemed to shorten the duration of GI-symptom episodes.”

In short, this study found that probiotics helped shorten GI symptom episodes in marathon runners, but had little effect on the incidence of respiratory infections.


  1. 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 Aug;17(4):352-63.
  2. Hao Q, Lu Z, Dong BR, Huang CQ, Wu T.  Probiotics for preventing acute upper respiratory tract infections.  Cochrane Database Syst Rev. 2011 Sep 7;9:CD006895.
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