Weighing up the evidence used by direct-to-consumer stem cell businesses

Hundreds of businesses across the United States offer direct-to-consumer stem-cell-based interventions that have not been approved by the Food and Drug Administration. Here, we characterize the types of evidence used on the websites of 59 stem cell businesses in the Southwest United States to market their services. We identify over a dozen forms of evidence, noting that businesses are less likely to rely on "gold-standard" scientific evidence,...