Communicating scientific evidence in qualified health claims.

Qualified health claims (QHCs) are found on food and dietary supplement labels and aim to communicate the quality and strength of scientific evidence for a diet-disease relationship. Since the evidence varies for diet-disease relationships, the language to describe the evidence also varies. However, research indicates that consumers misinterpret QHCs as a whole product evaluation. The FDA is reviewing the evidence ranking system for QHCs and the current study aims to inform future consumer research. A content analysis examined the language used to convey scientific evidence in 53 QHCs and organized them into an intrinsic scale of evidence. Results revealed 36 formats to present the evidence in 53 QHCs. Seventy-seven percent (n = 41) demonstrate a reading level above 9th grade. Most claims describe the quality of evidence (n = 51, 96%) ("very weak") and/or reference its consistency (n = 41, 77%), while a quarter (n = 13) also quantify the evidence ("two studies"). Twenty-five claims (47%) present the evidence before stating the diet-disease relationship. There is an absence of a systematic description of evidence among QHCs that may contribute to the misleading, albeit unintentional, nature of these claims. Policymakers might consider reforming QHC regulations so that a hierarchy of evidence for diet-disease relationships is clearly communicated to consumers.