The confidence level changes with the endpoint
The review reports moderate confidence for some outcomes, including fewer people experiencing at least three infections and reduced antibiotic use for these infections. Confidence was lower for several other outcomes, and absence from school or work remained very uncertain. [1]
Its evidence search was current to May 2022. This page reports that review’s scope, not an exhaustive assessment of every later study. [1]
Do not generalize across every product or immune function
The included trials involved specified preparations and populations. Their results do not establish that an arbitrary blend produces the same effect or improves every aspect of immunity. [1]
An infection-prevention endpoint also differs from treating an infection once it occurs. Keep the organism, regimen and measured outcome attached to any claim. [1]
Name the benefit rather than using a broad slogan
Imagine a review finds fewer repeated respiratory infections. That does not establish that the same preparation treats an active infection or prevents unrelated diseases.
| Detail | Interpretation |
|---|---|
| Repeated respiratory infections | One assessed outcome |
| Evidence certainty | Varies by endpoint |
| Immune boost | Too broad to substitute for results |
Sources for this article
- Can probiotics (live micro-organisms) prevent upper respiratory tract infections such as the common cold? | Cochrane
Source consulted: 2026-09-18. This is a reference resource, not a claim that we conducted the studies or tested a product.