Revisiting the Definition of 'Healthy' Participants in Substantiation of Structure/Function Claims for Dietary Supplements.

Concepts and definitions of 'healthy' have been evolving within clinical treatment algorithms as well as reference standards such as Body Mass Index and Dietary Reference Intakes. Consumers' perception of the word 'healthy' is also changing to reflect longer life span, need to stay active and in a good state of mental well-being while managing multiple diseases. Guidelines from the US Food and Drug Administration indicate that substantiating evidence for support of Structure/Function (S/F) claims for dietary supplements is best derived from clinical research conducted in a 'healthy' population. S/F claims cannot be represented to diagnose, treat, cure or prevent any disease. However, in this context, the term 'healthy' is non-descriptive and largely interpreted as an absence of disease. Guidelines for treatment of disease have been broadened to include biomarkers of disease risk such that the pool of 'healthy' volunteers eligible to be enrolled in clinical trials for S/F claim substantiation is greatly diminished. This perspective presents the challenges faced by the food and dietary supplement industry and by researcher efforts designed to substantiate S/F claims and suggest the phrase 'physiologically stable' or 'apparently healthy' as descriptions better suited to replace the term 'healthy.'