A Lone Voice in the Crowd: Probiotics in the Context of the Microbiome

The study of the human microbiome is transforming much of our understanding of human diet and it’s relation to health and disease.  Moreover, many of these studies are now making associations between particular microorganisms and groups of organisms and their impact on human disease states ranging from diabetes and obesity to cancer.  Related to this, research on probiotic microorganisms such as many Lactobacillus species have demonstrated compelling health benefits associated with their ingestion and therein lies a longstanding conundrum. How could an organism representing such a small fraction of the trillions of bacteria in human faeces have such an influence on human health?  In this talk a rationale for the efficacy of probiotics is given in the context of their complex microbiota niche.  Morever, examples of mechanisms of actions of probiotic cultures will be discussed which range from pathogen inhibition to the reduction of serum cholesterol.  These studies demonstrate the potential for manipulation of the human gut microbiota including the use of probiotics, antimicrobials and bacteriophage but highlights the complexity of the microbiome/host relationship.