[Probiotics].
Probiotics, living cultures of micro-organisms, are currently of great interest as counterparts to antibiotics. The idea behind the use of probiotics is that the development and stability of intestinal microflora can be enhanced. The protection against infections is increased, resulting in fewer health problems and increased productivity. The mechanism of action of probiotics is not yet known, although there are several hypotheses. There is increasing evidence to suggest that probiotics act by stimulating the host's immune systems. The only accepted example of effective protection against infections provided by living micro-organism is the 'Nurmi concept', whereby one-day-old chicks acquire an enhanced protection against Salmonella infections when they are administered the complex intestinal flora of older chicks. The effects of probiotics on the growth, feed conversion or production of farm animals are, even in specific situations, not consistent enough to consider their use out of economic considerations. Probiotics are used to (re)establish the intestinal flora of patients or persons with lactose intolerance. The claims that probiotics have cholesterol-lowering and anti-tumour actions are based on animal experiments and require further investigations.