What are probiotics?

What are probiotics?

Probiotics are good bacteria that are found in food or supplements. Probiotics are defined as “Live microorganisms that, when administered in adequate amounts, confer a health benefit on the host.” (WHO/FAO, 2002)

For a probiotic to qualify as a true probiotic, any health benefits must be proven by clinical trials. In addition, a probiotic product must contain the same strain(s) and dose used in clinical trials.

Probiotic myths

What is a probiotic strain?

Bacteria are classified according to their genus, species and strain. There are different strains of bacteria with different genetic compositions, resulting in different characteristics. Biological strains are populations of bacteria that descend from a single individual or pure culture. Bacteria of the same strain have certain characteristics that differentiate them from bacteria of other strains.

Different probiotic strains have different effects

Different probiotic products contain different probiotic strains. As a result, a probiotic product containing Limosilactobacillus reuteri (for example, L. reuteri NCIMB 30242) is not equal to another probiotic product containing another strain of Limosilactobacillus reuteri (for example, L. reuteri DSM 17938). It is for this reason that bacteria must be defined and tested at strain level in clinical trials. Different strains of the same bacteria may have different characteristics, just as a Chihuahua have other qualities than a Great Dane, even though both are dogs.

We need to clarify which strain we mean when we choose a probiotic. The fact that a product contains “Limosilactobacillus reuteri” is not enough. Species and strain names are needed to know what probiotic we are talking about and the benefits we can expect from it, for example, Limosilactobacillus reuteri DSM 17938. Furthermore, clinical trials must be conducted at strain level in order to be relevant.