Nutrition as Modulator of Oxidative Stress in Cancer Prevention and Treatment.

Cancer remains a leading global cause of morbidity and mortality, with oxidative stress playing a central role in its pathogenesis, progression, and response to therapy. Nutrition has emerged as a modifiable factor capable of influencing redox homeostasis, thereby contributing to both cancer prevention and therapeutic outcomes. This narrative review summarizes current evidence on dietary patterns, specific nutrients, and bioactive compounds that modulate oxidative stress and are associated with reduced cancer risk and improved response to treatment. A literature search was conducted using PubMed, Scopus, and Google Scholar, covering the period from 2002 to 2025 to capture contemporary dietary approaches and clinical evidence. Eligible studies addressed nutrient compounds, dietary strategies, obesity, gut microbiota, conventional cancer therapies, and clinical outcomes, with particular emphasis on mechanisms related to oxidative stress, inflammation, and immune modulation. Epidemiological evidence consistently supports the protective role of plant-based dietary patterns and reduced intake of red and processed meat, partly due to their antioxidant and anti-inflammatory properties. Nutrients such as dietary fiber, polyphenols, and omega-3 fatty acids are associated with decreased oxidative damage, improved immune responses, and enhanced therapeutic efficacy across multiple tumor types, including colorectal, breast, lung, and ovarian cancers, as well as glioblastoma. Emerging data also suggest that dietary interventions, including ketogenic diets and fasting, may influence tumor metabolism and redox balance, potentially increasing sensitivity to conventional therapies. The gut microbiota has been identified as a key mediator linking diet, oxidative stress, and cancer-related pathways. Although current evidence supports the role of nutritional strategies in targeting oxidative stress for cancer prevention and treatment, further large-scale randomized clinical trials are required to clarify their impact on survival and treatment efficacy. The integration of nutritional counseling into oncology practice represents a cost-effective, accessible, and patient-centered approach with the potential to modulate oxidative stress and improve clinical outcomes.