Defined by the World Health Organisation as “Live microorganisms that when administered in adequate amounts, confer a health benefit on the host”. Probiotics are described first by genus, then species and then by strain (i.e. Bifidobacterium infantis 35624).

There are significant differences in their functions even at the strain level; therefore, for example, only because this specific strain (Bifidobacterium infantis 35624) was shown to benefit people with IBS (human trials), it does not mean that all other Bifidobacterium strains will have the same effect!