Uncertainty communication, trust and health promotion.

Health promotion is more effective when health communicators are considered trustworthy. However, health communicators must often deal with uncertainties in the knowledge base on which they rely. In this commentary, we discuss the benefits of acknowledging uncertainty, with caveats and best practices to cultivate trust. We recommend determining the type of uncertainty involved and selecting appropriate communication approaches. We also advise that communicators emphasize the positive elements of the uncertainty, whenever possible, such as when it reflects a growing evidence base. Health promoters should consider the long-term outcomes of communicating uncertainty, as these may differ from the short-term outcomes. We identify knowledge gaps and areas ripe for future research. We also show that uncertainty can often be communicated without harming trust in the communicator, and that communicators should rely on evidence-based best practices. We aim to provoke further discussion on how uncertainty should be understood and framed in health promotion efforts, guiding communicators on how to maintain public trust amid unknowns.