Dietary Antioxidants and Redox Signaling in Cancer Prevention: Mechanistic Insights and Metabolic Inflammation

Oxidative stress is an important component of cancer biology with an imbalance between the production of reactive oxygen species (ROS) and antioxidant defense systems. Excess ROS can cause molecular damage and genomic instability. At the same time, ROS signaling remains necessary for normal cellular function. Redox homeostasis is of particular importance in this balance. The role of dietary antioxidants in cancer prevention is complex, depending on the biological context. This narrative review used preclinical and clinical studies to synthetize the current literature. We performed an extensive literature search of Scopus, Web of Science, and PubMed. We focused on articles published between 2021 and 2026. Dietary antioxidants influence redox biology in cancer. It focuses on major redox-sensitive pathways, including Nrf2-Keap1-ARE signaling, AMPK-mTOR regulation, NF-κB-mediated inflammation, mitochondrial quality control (autophagy and mitophagy), and inflammasome activation. These pathways involved in tumor initiation and progression link oxidative stress to metabolic and inflammatory processes. Current evidence suggests that dietary antioxidants act primarly by supporting endogenous defense systems. This may help explain the “antioxidant paradox,” in which antioxidant-rich dietary patterns are associated with a lower risk of cancer. In some studies, high-dose supplementation with isolated antioxidants has produced inconsistent or sometimes adverse results. These effects depend on dose, chemical form, metabolic context, and initial redox state. The gut microbiota is also an important mediator of antioxidant bioactivity. The gut microbiota modulates systemic redox balance by converting dietary polyphenols into bioactive metabolites, not acting only as simple scavengers. This contributes to inter-individual variability. Dietary antioxidants act as modulators of redox signaling. Personalized redox modulation may guide future cancer prevention strategies, emphasizing whole-diet approaches and biomarkers.