In both animal and human nutrition there is a lot of interest in how bacteria normally present in the gut can be encouraged (e.g. by the use of prebiotics, probiotics, etc.). to be active and proliferate, to the cost of any potential pathogens which enter the system. Since this is the first review (that we know of) which addresses the question of how their activity could be related to health, we suppose that other workers are interested in a "bird's eye view" of the subject.

Not really, given that it is a review of the literature, but we hope that it's a useful summary of the field, which will be useful for others.

This review relates what is known about the activity of the huge number of bacteria which normally live in the gut, in relation to how they can have a positive influence on animal health. It's a subject that is interesting at the moment, to a large extent because of all the concerns relating to the buildup of antibiotic resistance in the environment. The idea is that if you can avoid the use of some antibiotics by adding particular carbohydrates to the diet to improve health, that this has to be beneficial from an ecological point of view, as well as from a human health standpoint in the longer term.

We realized that the routine use of antibiotics as growth promotors in animal diets was not sustainable, even though that kind of use is by no means the largest source of residues in the environment. However, in the 1970s Professor van der Waaij, from the University of Groningen in the Netherlands, had proposed this idea of "colonization resistance," that the normal bacteria living in the gut could play an important part in preventing invasion by pathogens. So we wanted to look more closely in that field and find out what we, as animal nutritionists, could contribute. From the time of this article this subject has really taken off, and we are now working together with microbiologists and immunologists to find out how the whole system works as a whole. It's really exciting.

Dr. Barbara A. Williams
Animal Nutrition Group,
Wageningen University,
The Netherlands