Omega-9 Fatty Acids in Inflammation and Cancer Management: A Narrative Review
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Abstract
Background: Chronic low-grade inflammation contributes to metabolic dysfunction, oxidative stress, immune dysregulation, and cancer-related biological processes. Omega-9 fatty acids, particularly oleic acid, are monounsaturated fatty acids abundant in olive oil, avocados, nuts, seeds, and several animal-derived foods. Although omega-9 fatty acids are not essential fatty acids, increasing evidence suggests that they may influence inflammatory signaling, oxidative balance, lipid metabolism, and cellular pathways relevant to cancer-risk modulation. Objective: This narrative review aimed to synthesize current evidence on the potential role of omega-9 fatty acids, especially oleic acid, in inflammation regulation and cancer-related biological pathways. Methods: Relevant mechanistic, experimental, observational, dietary intervention, and review literature was narratively synthesized to evaluate the effects of omega-9 fatty acids and omega-9-rich dietary sources on inflammatory cytokines, oxidative stress, immune-cell activity, metabolic regulation, apoptosis, angiogenesis, tumor-cell proliferation, and cancer-risk outcomes. Evidence was organized thematically, with attention to differences between isolated oleic acid, olive oil, extra-virgin olive oil, and Mediterranean dietary patterns. Results: The most consistent evidence supports anti-inflammatory and metabolic effects of omega-9-rich exposures, including modulation of TNF-α, IL-6, COX-2, NF-κB-related signaling, oxidative stress markers, lipid metabolism, and mitochondrial function. Human dietary evidence, particularly from olive-oil-rich Mediterranean dietary patterns, suggests favorable effects on inflammatory and cardiometabolic biomarkers. Cancer-related evidence indicates biologically plausible effects on HER2-related signaling, apoptosis, angiogenesis, tumor-cell proliferation, and tumor microenvironment interactions, but these findings remain largely preclinical or indirect. Human evidence for cancer prevention is suggestive, especially in Mediterranean-diet contexts, whereas direct evidence for cancer management remains limited. Conclusion: Omega-9 fatty acids, particularly oleic acid, appear to be supportive dietary components with the strongest evidence for inflammation reduction, oxidative balance, immune modulation, and metabolic improvement. Their role in cancer prevention is plausible but not independently established, and they should be considered part of broader preventive dietary strategies rather than direct anticancer interventions
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