Nutritional support in colorectal cancer patients

Colorectal cancer (CRC) remains the third most commonly diagnosed cancer worldwide, with malnutrition, sarcopenia, and cachexia affecting a substantial proportion of patients across the disease trajectory; malnutrition in particular is associated with increased postoperative complications, poor chemotherapy tolerance, prolonged hospitalisation, and reduced survival, yet remains under-recognised and inconsistently addressed in routine clinical care. This thesis evaluates the role and efficacy of nutritional support in colorectal cancer patients across the full treatment continuum, from prehabilitation and surgery through active oncological treatment to long-term survivorship, with particular focus on immunonutrition, artificial nutrition, targeted micronutrient supplementation, and gut microbiome modulation. A narrative literature review was conducted using PubMed, PubMed Central, Scopus, ScienceDirect, and relevant publisher databases, guided by structured search terms and explicit inclusion/exclusion criteria, synthesising evidence across nutritional screening tools, phase-specific interventions, and specialised nutritional strategies, with emphasis on clinical outcomes including complication rates, length of stay, chemotoxicity, and survival. Malnutrition was found to affect 27–46% of CRC patients depending on assessment criteria, with prevalence exceeding 60% during active chemotherapy; multimodal prehabilitation reduced postoperative complications by up to 25 percentage points in high-risk cohorts, perioperative immunonutrition reduced infectious complications by 38% and anastomotic leak rates by approximately 30%, and ERAS-based nutritional protocols shortened hospital stay and accelerated gastrointestinal recovery. Nutritional support during chemotherapy improved quality of life and nutritional indices more consistently than body weight, while malnutrition, rather than sarcopenia alone, independently predicted long-term survival. Overall, the evidence indicates that nutritional support delivered early and consistently across the CRC care continuum meaningfully improves clinical outcomes, and that systematic screening, phase-adapted intervention, and closer integration of nutritional care into standard oncological practice are warranted to reduce complications and improve survival and quality of life.