Common ColdInfectionPre, Pro, Synbiotics

Probiotic effects on respiratory tract infection

 Reviewers at the Alfa Institute of Biomedical Sciences in Athens, Greece evaluated the evidence.

First, the details.

  • The reviewers identified 14 well-designed studies of probiotics for the prevention of upper or lower respiratory tract infections (RTIs).
    • 12 in healthy subjects and 2 involving patients with RTIs.
  • Various Lactobacillus strains were used in 7 studies, combinations of Lactobacillus and Bifidobacterium strains were used in 5 studies, and a Bifidobacterium strain and a non-pathogenic Enterococcus faecalis strain were each used in 1 study, respectively.

And, the results for various aspects of the studies.
The risk of getting a RTI

  • 4 studies favored probiotics to reduce risk.
  • 10 studies reported no effect with probiotics vs the comparative group.

Symptom control

  • 5 of 6 studies reported reduced symptoms with probiotics.

Duration of infection

  • 3 of 9 studies reported shorter RTIs with probiotics.
  • No difference was found in the remaining 6 studies.

The bottom line?
The authors concluded, “Probiotics may have a beneficial effect on the severity and duration of symptoms of RTIs but do not appear to reduce the incidence of RTIs.”

It’s probably an oversimplification to report on probiotics as a group. However, there were probably too few studies to warrant reporting their individual effects.

A primer on pre, pro, and synbiotics is here.

2/1/09 18:36 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.