There may be a significant difference between the pharmaceutical-grade probiotics that show promise in clinical trials and probiotics in foodstuffs.
Episodes of acute infectious diarrhoea, particularly in children (there are few studies involving adults), aiming to shorten the duration of diarrhoea and reduce stool frequency.
When used in conjunction with oral rehydration, probiotics have been shown to reduce the duration of diarrhoea by around 25 hours, decrease the risk (by almost 60%) of diarrhoea lasting longer than four days; and reduce the frequency of diarrhoea on day 2 after the intervention. Due to the marked variability in study findings, these figures are approximate.
Probiotics have several actions in the gut, including actively competing with pathogens for nutrition, making gut contents acidic, secreting local antimicrobial agents, and enhancing specific and non-specific immune responses.