More patients are turning to probiotics for the promotion of digestive health, but can they also help patients avoid acute upper respiratory tract infections (URTIs), such as the common cold? A new review in the Cochrane Library sought to assess the efficacy of probiotics in helping patients without immunodeficiencies prevent URTIs compared to placebo.

Thirteen randomized controlled trials (RCTs) were identified with 3,720 study participants, including both children and adults from eight countries. Probiotics were superior to placebo in reducing the number of participants experiencing acute URTI episodes by approximately 47%; the duration of an episode was also lowered by about 1.89 days. Antibiotic prescription rates for URTIs and related school absences were reduced as well with probiotics vs. placebo. Gastrointestinal symptoms were the most common side effects, although minor. However, the quality of evidence was low or very low due to issues with the trials, such as unclear randomization and blinding and small sample sizes.

While probiotics may be more beneficial than placebo for preventing acute URTIs, the quality of evidence in these studies was low or very low. Additional trials with improved methodologies are needed to support this conclusion.