Gut Flora in Health and Disease:

In a young evolving science, there are always more questions than answers. That is also the situation in the emerging field of Probiotics, and this was made very clear at the International Probiotics Workshop in Amsterdam. In the report of this workshop, we present a selection of the most urgent questions in the field of probiotics. In addition, we propose a few strategies for the future of probiotics research. During the workshop, 120 experts from disciplines including Human Nutrition, Gastroenterology, Nutritional Therapy, Cell Biology, Microbiology and Immunology discussed new views on microbe-host interactions and the role of probiotics in prevention and alleviation of gastro-intestinal, atopic and auto-immune diseases. There is a general consensus among the experts that administering defined strains can help in preventing and curing gut flora related diseases: the first clinical trials show a promising role for probiotics. But the system is very complex, and most underlying mechanisms are still unclear. Rapid progress in this field will depend largely on the collaboration between fundamental researchers from different disciplines and medical specialists. Besides, more clinical studies are required to convince authorities and the public of the value of microbial therapies. Do we need another term for Probiotics? Many people including those who buy products containing probiotics in supermarkets and health shops do not seem to have problems with the term probiotics. Probiotics are seen as ‘good’ bacteria that improve your health. As the FAO/WHO defined more precisely: ‘Probiotics are live micro-organisms which, when administered in adequate amounts, confer a health benefit on the host’. In fact the term probiotics is relatively well defined by the International Scientific Association for Probiotics and Prebiotics (www.isapp.net). But the term is misused by a number of companies that bring products on the market of dubious quality and with vague unproved claims. This situation prompted some of the speakers to suggest abandoning the term Probiotics. “Shouldn’t we leave the term Probiotics?” one of them asked. He was supported by others who suggested it is difficult to prove a general health claim such as ‘this strain improves your gutflora, which will make you feel better’. How can a company validate such a broad claim? Contrary to probiotics with such a general health claim, the claims for probiotics curing particular diseases can be proved with clinical trials. So, for use as a registered therapy to cure particular gutflora-related diseases, some delegates proposed the term ‘bacterial therapy’ or ‘microbial therapy’ or ‘bacterial immunomodulators’. However, not everybody agreed with choosing a new term for probiotics. “Whether or not the producers want to sell it as a food or a drug, all probiotics must, by definition be proven to confer a health benefit that is measurable and shown by clinical trials”, said Dr. Gregor Reid from the University of Western Ontario in Canada. So rather than change the name, he stated, producers need to change, so that consumers and healthcare providers are clear what is truly a probiotic and what is not. Also the FAO/WHO preferred to retain ‘probiotic’ with the hope that in time its proper definition will be adhered to. So there was no agreement about a special term for medical use of probiotics. However, one can argue that it is possible to use both new terms such as ‘bacterial’ or ‘microbial therapy’ and the term ‘probiotic’, depending on the context. How can fundamental ‘mechanism-studies’ be integrated with clinical ‘disease-studies’? During the symposium, several specialists demonstrated direct and indirect effects of particular bacterial strains on immune cells, the mucosal barrier and gut-motility. Others showed for example the effects of stress on gut permeability or on the regulation of the mucosal barrier function by neuro-immune factors. Almost all experiments in this scientific field of mechanisms are done in vitro and in animal models – mostly rats and mice. In addition to these fundamental studies, medical specialists demonstrated the effects of defined strains on gut-florarelated diseases in patients. Dr. Dominique Brassard from Rhodia summarised the results of the first clinical trials with bacterial therapies. In Pubmed, he had counted 97 randomised controlled trials with patients. Most studies, For the programme of this workshop and abstracts of lectures, readers