The Gut Microbiome As an Indicator of Readiness for Head & Neck Cancer Surgery

Inclusion Criteria: * Adult patients (age 18+) * Male or female * Diagnosis of head and neck cancer that will be treated with major surgery * Major surgeries included will be any free flap reconstruction, any regional flap reconstruction (including pec major, submental flap, and supraclavicular artery island flap), oral composite resection, oropharyngectomy, total laryngectomy, cutaneous malignancy if it includes a free flap or regional flap reconstruction, parotidectomy if it includes a free flap or regional flap reconstruction, maxillectomy with or without orbital exenteration, lateral temporal bone resection, and/or a radical neck dissection if it includes a free flap or regional flap reconstruction * Diagnosis of moderate (Stage B) or severe (Stage C) malnutrition, based on the patient-generated subjective global assessment (PG-SGA) * Ability to speak and comprehend English * Ability to consent for themselves Exclusion Criteria: * Age less than 18 years * Inability to speak and comprehend English * Inability to consent for themselves * Pregnancy * Allergy to fish oil or fish * Gastrointestinal disorders (IBD, colon or rectal cancer, previous colon or small intestine resection) * Autoimmune disorders requiring medication * Chronic immunosuppression (i.e., transplant patients) * Leukemia * Stage III or higher Chronic Kidney Disease (CKD) * Cirrhosis * Pancreatitis