Probiotics and Prebiotics

The WHO defines probiotics as 'live microorganisms that, when administered in adequate amounts, confer a health benefit on the host.' The critical detail is strain specificity: Lactobacillus rhamnosus GG has strong evidence for preventing antibiotic-associated diarrhea, but Lactobacillus rhamnosus HN001 does not—and both are 'Lactobacillus rhamnosus.' A label saying 'contains Lactobacillus' without the strain designation is scientifically meaningless for predicting health benefits. Furthermore, probiotics must be alive and in sufficient quantity (typically 10^8-10^10 CFU per dose) at the time of consumption—dead bacteria do not confer the same benefits.