A Preliminary Elucidation of the Role of Dietary Fiber in Mitigating Sarcopenia Risk in Head and Neck Cancer - PROJECT SUMMARY/ABSTRACT Sarcopenia remains a consequential prognostic factor that drastically affects morbidity and mortality in head and neck cancer (HNC). Due to the catabolic state associated with sarcopenia, dietary strategies emphasizing energy and protein intake are often encouraged. However, data suggest underlying mechanisms (e.g., inflammation) drive the development of sarcopenia independent of energy or protein intake. Dietary fiber is notably anti- inflammatory and has capacity to improve sarcopenia and other cancer-related outcomes, in part via production of short chain fatty acids (SCFA) and decreased inflammation. This precise relationship is yet explored in HNC. Moreover, it is unknown how patients perceive the feasibility of increasing their dietary fiber intake during treatment. This study seeks to evaluate dietary fiber intake longitudinally from the time of diagnosis for a total of six months in patients diagnosed with HNC, and to elucidate the relationship between dietary fiber intake and measures of SCFA, inflammation, and sarcopenia. Adults newly diagnosed with HNC will be recruited and provide iterative assessments of dietary fiber intake (National Cancer Institute Diet History Questionnaire III [DHQIII] and 24-hour recalls), SCFA (stool samples analyzed using gas-phase chromatography), inflammatory markers (venous blood samples and multiplex kits), skeletal muscle quantity and quality (CT scans analyzed using SliceOMatic), muscle function (Timed Chair Stands, Leg Press Power), and perceptions regarding the feasibility of targeting dietary fiber (semi-structured interviews [SSIs], surveys). Our central hypothesis is that lower dietary fiber intake will significantly predict development of sarcopenia, decreased SCFA, and increased inflammatory markers. In Aim 1, we will determine the relationship between dietary fiber intake, SCFA, inflammatory markers, and skeletal muscle measures in patients being treated for HNC. In Aim 2, we will characterize the feasibility (acceptability, demand, practicality, implementation) of targeting dietary fiber in patients with HNC according to patient perceptions (SSIs, surveys) within Health Belief Model constructs and review of study records (e.g., retention, completion of data collection). This proposal will generate fundamental knowledge and explore the clinical application of this knowledge to support future clinical trials that have the potential to lead to substantial paradigm shifts that could contribute to immense improvements in HNC prognosis.