Probiotic is a term used to describe certain bacteria that are believed to provide health benefits when ingested. The term itself isn’t formally regulated and there are few regulatory restrictions on how products may use the term on their labels.

The World Health Organization defines probiotics as such:

Live microorganisms, which when administered in adequate amounts confer health benefits to the host (PDF).

This highlights two very important qualifying attributes of any compound to be considered as probiotic—adequate amounts and health benefits. This can be interpreted to mean the following two things:

  1. Bacteria must have been observed to offer health benefits under clinical settings.
  2. Dosages used to produce health benefits in clinical settings must be reasonably achievable, both in terms of finance and safety.
  3. Bacteria species should be the same as used in clinical settings.

Different bacteria species can vary wildly in genetic composition. Researchers failing to denote specific strains are doing their field a disservice. Marketers and product developers doing so are doing a disservice to their consumers.