Probiotics, infection and immunity

Taking live bacteria by mouth to improve health (probiotics) is not intuitively rational yet it is a practice with a long history. As interest in the effects on health of the intestinal flora has developed, along with major advances in the technology for studying it, so has come a new interest in establishing the true benefits of probiotic therapy. This review summarizes the most recent contributions to this rapidly developing area.Probiotic bacteria, mainly bifidobacteria and lactobacilli for historical reasons, can prevent or ameliorate some diseases. Many empirical studies have been done, but work to develop the ideal characteristics of probiotics lags behind. Current literature covers survival of probiotics in the gut, mucosal adherence, antibacterial/pathogen mechanisms, effects on immune function and clinical studies.Probiotic bacteria are effective in preventing and reducing the severity of acute diarrhoea in children. They are also useful in antibiotic associated diarrhoea but not for elimination of Helicobacter pylori. In inflammatory bowel disease, especially ulcerative colitis, probiotics offer a safe alternative to current therapy. Probiotics have been used to prevent urogenital tract infection with benefit and, perhaps more intriguingly, to reduce atopy in children. Probiotics do not invariably work and study of mechanisms is urgently needed.