A gut-full of 'good' microbes.

The article reports on the roles of so-called commensal "probiotic" bacteria, such as what is present in yoghurt, in animal health and development. The author cites the European Food Safety Authority's having turned down most applications from manufacturers for recognition of their products as probiotic. He discusses faecal transplants, a procedure sometimes applied to alleviate certain types of colitis and other conditions, and says the success of such an approach would depend crucially on knowing which probiotics are needed to exert which effects.