Young children living in low- and middle-income countries suffer several episodes of infectious diarrhoea each year. The main risk to health is dehydration, and although most episodes are self-limiting, diarrhoea accounts for about 15% of all deaths in the under fives. In industrialized countries deaths from infectious diarrhoea occur mainly in the elderly. Acute diarrhoea can be caused by several types of viruses, bacteria and parasites; the most common agents are rotavirus, enterotoxigenic E. coli and Shigella. In practice, in most episodes of acute diarrhoea the causative agent is not identified, and treatment is aimed at preventing dehydration, shortening the duration of the illness, and reducing the period that a person is infectious.
Probiotics are used to treat infectious diarrhoea because it is known that they compete against other enteric pathogens for available nutrients and binding sites, help make the gut contents acid, and increase immune responses. Well-known probiotics are the lactic acid bacteria and the yeast Saccharomyces. This review, a substantial update of the original version first published in 2003, includes participants of all ages, and randomized or quasi-randomized studies, using specific probiotics. It excludes trials which used yogurt or other non-identified fermented foods.
The review includes 63 studies with 8014 participants, mostly children. The majority of studies were conducted in countries with low or very low child and adult mortality, and tested different probiotics – mostly live preparations of lactic acid bacteria and bifidobacteria. There was considerable variability in the methodological quality of included trials.
Results indicate a clear beneficial effect of probiotics in infectious diarrhoea, consistent across the different study outcomes with almost no adverse effects. However, there were wide variations in the treatment regimens and in the probiotics used, and the authors recommend further trials with standardized definitions for acute diarrhoea and the resolution of the illness, with a reliable identification of the probiotic in use. More research is needed to assess the role of probiotics in developing countries.
Cochrane Database of Systematic Reviews 2010, Issue 11. Art. No.: CD003048. DOI: 10.1002/14651858.CD003048.pub3.