Probiotics: a perspective on problems and pitfalls.

Therapeutic manipulation of gut flora with probiotics promises to be a useful strategy for several disorders, including infectious, inflammatory and neoplastic conditions. However, there are large gaps in the knowledge of the normal flora and of the optimal use of probiotic products. At present, there is no reliable in vitro predictor of in vivo efficacy of putative probiotics. Indeed, probiotic performance should be defined in the context of the disease indication for which it is intended. This will require rigorous prospective clinical trials. In addition, guidelines for routine clinical use of probiotics are confounded by insufficient data on optimum strain selection, dose, delivery vehicle and monitoring. Before the promise can be fulfilled, problems and potential pitfalls with probiotic therapy need resolution.