They show promise, but bigger studies are needed

Papers p 1327

Concerns about antibiotic resistance have lead to an increased interest in alternative approaches for controlling common childhood infections. Since prevention would obviate the need for treatment, the prophylactic use of probiotic bacteria to prevent these illnesses has been proposed, and a study in this week's issue examines the effect of a probiotic milk on diarrhoeal and respiratory infections in children attending day care centres in Finland (p 1327).1

Probiotics are viable bacteria that colonise the intestine and modify the intestinal microflora and their metabolic activities, with a presumed beneficial effect for the host, 2 3 Many of these probiotics are lactic acid bacteria, such as lactobacillus or bifidobacterium, but not all probiotics have the same characteristics and, presumably, not the same efficacy.3 To be effective a probiotic must be able to survive passage through the acidic environment of the stomach and grow in and colonise the intestine, even in the presence of antibiotics.4^–6 To be widely used a probiotic must also be safe.7 Lactobacilli are generally regarded as non-pathogenic, as they occur naturally in the intestine. …