From gut biomarkers to daily participation: reframing outcome assessment in dietary intervention research for autism spectrum disorder

Biological research on dietary interventions in autism spectrum disorder (ASD) is advancing rapidly, with increasing attention to gastrointestinal, microbiome, inflammatory, and metabolic mechanisms. However, biological responses may not necessarily translate into meaningful changes in feeding behavior, daily functioning, or participation. Feeding difficulties in autistic children are shaped by interacting gastrointestinal, sensory, behavioral, environmental, and family factors. This Hypothesis and Theory article proposes the BIO-PART framework as an ICF-informed, multidimensional approach for evaluating the translation of biological responses into meaningful everyday feeding and mealtime-participation outcomes. BIO-PART is specifically focused on feeding and mealtime participation rather than serving as a general framework for all autism-related outcomes. The framework integrates five complementary domains: biological, clinical, functional, participation, and family/contextual outcomes. It is hypothesized that biological improvements alone will not consistently predict improvements in functional feeding and real-world mealtime participation, and that these relationships are moderated by sensory, behavioral, and contextual factors rather than confounded by them. The framework proposes that future dietary intervention trials should prespecify multidomain outcomes, consider clinically relevant feeding profiles, and incorporate multidisciplinary assessment involving biomedical and rehabilitation professionals. BIO-PART is intended as a testable conceptual framework rather than a validated clinical instrument; prospective longitudinal and randomized studies, beginning with a consensus (Delphi) step, are needed to evaluate its validity, feasibility, and clinical utility.