Abstract
Probiotics for preventing illness or improving health have become increasingly popular with consumers, researchers, and producers, both dairy companies and alternative medicine providers. They are widely available in foods such as yoghurt and as freeze dried capsules. They are used both for their general health effects on the gut including reducing travellers and antibiotic related diarrhoea. Their most important and best researched use is in the treatment of necrotising enterocolitis in premature babies where they reduce incidence, severity and mortality. The ultimate 'probiotic' mixture might be healthy human faeces which have been used for transplantation in patients with antibiotic resistant Clostridioides difficile infections with some success. Studies of allergy prevention using probiotics have shown mixed results. In New Zealand however, a specific strain of Lactobacillus rhamnosus (HN001) given from birth for two years has been shown to reduce the prevalence of allergic disease in infants throughout childhood. Further studies have shown a reduction in gestational diabetes amongst mothers who consume the probiotic during pregnancy. An important feature of the clinical use of probiotics is that different strains within the same species may have very different effects.