Introduction: Although inflammation is defensive and healing process that maintains organ homeostasis, unresolved inflammation can lead to diseases. Polyunsaturated fatty acids (PUFAs), especially n-6 PUFAs abundant in Western diet, are precursors of pro-inflammatory mediators, whereas n-3 PUFAs possess anti-inflammatory properties. Therefore, interest in the cancer-preventive effect of n-3 PUFAs is increasing.

Areas covered: We have observed significant reductions of gastrointestinal tumorigenesis in the Fat-1 transgenic mouse as evidenced that the decrease in Helicobacter pylori-infected gastric tumorigenesis, colon, biliary, and pancreatic cancer was seen in Fat-1 mice producing n-3 PUFAs. However, despite many studies showing benefits, evidence-based medicine regarding molecular pathology, epidemiology, and clinical achievement of cancer prevention of n-3 PUFAs are still limited.

Expert commentary: Primary deficiency of eicosapentaenoic acids and docosahexaenoic acids in Western diets can explain the risk of cancer development and the importance of n-3/n-6 PUFA ratio in reducing cancer risk. Alteration of cell membrane composition during carcinogenesis is particularly important, due to increased rate of lipid/cholesterol synthesis in cancerous tissues. Here, we discuss that direct incorporation of n-3 PUFAs in the cell membrane corrects abnormal cellular proliferation and decreases inflammation-associated carcinogenesis. This is exemplified by cancer-preventive effects of n-3 PUFAs as fat sources for gastrointestinal cancers.

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