For a bacterium to be called ‘probiotic’ it must be alive and deliver benefit to the host species, this is a definition set down by the World Health Organisation (WHO). Any bacteria which do not deliver benefit are not probiotic, similarly it is wrong to refer to freeze-dried, deactived bacteria as probiotic. They only become probiotic if they return to life and begin to divide and confer benefit.

An alternative question to the one in the title would be to ask ‘which strains of probiotic bacteria confer most benefit to the host?’ Continue reading →