PROJECT SUMMARY The fragile population of children with medical complexity (children with congenital or acquired multisystem disease, neurologic impairment and/or dependence on medical technology) accounts for up to one third of all pediatric medical expenditure. Systematic investigation of the contribution of nutrition to chronic disease burden in this population has not been done and is urgently needed, as it has vast potential to optimize clinical outcomes such as feeding intolerance, improve quality of life and reduce healthcare cost. Dr. Bridget Hron is a pediatric gastroenterologist and nutrition specialist with advanced training in the nutritional regulation of metabolism and inflammation who is perfectly suited to address this critical unmet need. Her career goal is to direct a clinical research program focused on discovering evidenced-based, state of the art nutritional interventions that transform the clinical care of the most vulnerable pediatric population. In Dr. Hron's recent work, she has shown that blenderized diets, which are pureed high quality table foods such as fruits, vegetables, meat and legumes administered via gastrostomy tube have a beneficial effect on health care utilization, reducing admissions for pulmonary reasons by 53%. Over the course of this career development award, Dr. Hron will study the effect of blenderized feeds varying in viscosity on gastrointestinal symptoms and on esophageal and gastric function. The innovative aggregate randomized, controlled N-of-1 study design outlined in this proposal allows each individual participant to determine diet of maximal efficacy, but also allows for estimation of population effect of the interventions. The exceptional mentorship and original scientific training proposed in this career development award are critical for Dr. Hron's academic development. Dr. Rachel Rosen, primary mentor, is an expert in aerodigestive medicine, and Dr. Christopher Schmid, co-mentor, is an expert in biostatistics with a focus on N-of-1 trials – both have outstanding backgrounds in clinical research with deep commitment to mentorship. She will be supported by her Scholarship Advisory Committee consisting of Drs. Wayne Lencer, Christopher Duggan, Jay Berry and Sharon Donovan, who lend content-area expertise. Her formal training will include a Master of Science: Concentration in Food Science at University of Illinois Urbana-Champaign, advanced courses in statistical analysis at the Harvard T.H. Chan School of Public Health (HSPH), personal instruction on mediators of esophageal and gastric motility by Dr. Rosen, and professional development courses through HSPH and Harvard Catalyst. Her training and research activities will be conducted in the unparalleled academic environments of Boston Children's Hospital and Harvard Medical School, which are firmly committed to Dr. Hron's successful transition to an independent research career.