probiotics, prebiotics and the gut microbiota - International Life ...

Probiotics, Prebiotics and the Gut Microbiota 27thus opening up the possibility of alternative mechanismsimpacting the immune system.Although studies in humans have found changes inbiomarkers such as cytokine levels and changes in thenumber and activity of immune cells, it is nevertheless ofprime importance to have studies in human subjects thatalso measure clinical outcomes. Clinical measures, suchas a reduced incidence of infection or enhanced immuneresponse to a vaccine, can then be linked to measuresof humoral or cellular immune biomarkers. Eventhough results from animal studies cannot necessarilybe extrapolated to humans, in vivo studies in animalmodels represent a valuable means of understandingthe complex signalling cascade underlying a protectiveimmune response.OVERALL CONCLUSIONSThe science around the concept of probiotics andprebiotics continues to expand. Current global researchefforts have greatly contributed to the understanding ofthe role of GI commensal organisms in their extraordinarysymbiotic relationship with humans. Continued researchinto the microbiota will no doubt help lead to an improvedinsight into the impact of probiotics and prebiotics onhuman health.Probiotics are designed to provide added functions thatcan compensate for, substitute for, or add to the gutmicrobiota, and therefore impact the host directly orindirectly through “cross-talk” with the gut microbiotaand/or the host. In addition, the effects may be local in theGI tract or systemic. Prebiotics are designed to improvethe intrinsic microbiota by selectively stimulating thosegroups that are thought important for eubiosis.Research over past decades has demonstrated potentialhealth benefits of dietary probiotics and prebiotics andcontributed to our understanding of the mechanismsby which these effects are brought about. The mostcommonly reported impact of probiotics and prebioticsis on intestinal function, including transit time, AAD andinfectious diarrhoea. Evidence continues to emergethat probiotics and prebiotics have an influence on theimmune system and thereby may enhance resistance toinfections, particularly those of the GI or respiratory tract,and help to mitigate allergies, particularly in infants andyoung children. Evidence is gradually developing for thepotential for probiotics and prebiotics to impact otherconditions of the GI tract, such as IBD, IBS and coloncancer. In the case of prebiotics, a well-established rolein enhancing calcium absorption remains to be a provenbenefit for bone health.