Colon Cancer Risk Depends on Interaction Between Omega-3s and Inflammation Genes
Colon cancer risk? Due to interaction between Omega 3 and inflammation genes
Omega 3 reduce the risk of colorectal cancer by interacting with genes that control inflammation. A research team led by Nina Habermann from the National Center for Tumor Diseases in Heidelberg (Germany) demonstrated the existence of this interaction. The study was published in the journal Genes and Nutrition1. The researchers found that individuals consuming low amounts of Omega-3 rich foods have a higher probability of developing this cancer if they carry genes that increase levels of pro-inflammatory molecules.
The role of Omega-3 in inflammation
Polyunsaturated fatty acids include both Omega-3 and Omega-6. They are converted by the body into prostaglandins and leukotrienes, molecules that regulate inflammatory processes. Generally, substances produced from Omega-6 have effects opposite to those derived from Omega-3: the former stimulate inflammation, while the latter reduce it. Several studies have shown that Omega-3 intake reduces inflammation, helping to counteract various disorders linked to this phenomenon. Among these is colorectal cancer, a tumor type also associated with inflammatory bowel diseases such as ulcerative colitis and Crohn's disease. The incidence of this cancer is significantly lower in populations consuming high amounts of Omega-3 rich fish2. Furthermore, intake of EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), the two main Omega-3s found in fish oil, decreases the formation and proliferation of precancerous polyps3,4. Given the links between Omega-3, inflammation, and colon cancer, Habermann and colleagues hypothesized that consuming high amounts of Omega-3 rich fish might reduce colorectal cancer risk in people carrying genes that increase pro-inflammatory molecule levels.
Genes that promote inflammation
The researchers compared genes from 1,574 individuals with colon cancer and 791 patients with rectal cancer to those in subjects without these tumors. They found that consuming low levels of Omega-3 increases cancer risk if variants of the genes PTGS1, PTGS2, and ALOX15 are present, which lead to higher production of prostaglandins and leukotrienes. In particular, cancer risk is higher for carriers of this PTGS1 variant who consume low DHA levels. Similarly, cancer is more frequent if individuals with the ALOX15 form that increases inflammation consume little EPA. Based on these findings, the researchers concluded that the combination of Omega-3 levels and gene variants present in the body can determine the risk of developing colon cancer.
Sources 1. Habermann N, Ulrich CM, Lundgreen A, Makar KW, Poole EM, Caan B, Kulmacz R, Whitton J, Galbraith R, Potter JD, Slattery ML, “PTGS1, PTGS2, ALOX5, ALOX12, ALOX15, and FLAP SNPs: interaction with fatty acids in colon cancer and rectal cancer”, Genes Nutr. 2012 Jun 8. [Epub ahead of print] 2. Schloss I, Kidd MS, Tichelaar HY, Young GO, O'Keefe SJ, “Dietary factors associated with a low risk of colon cancer in coloured west coast fishermen”, S Afr Med J. 1997 Feb;87(2):152-8 3. Anti M, Marra G, Armelao F, Bartoli GM, Ficarelli R, Percesepe A, De Vitis I, Maria G, Sofo L, Rapaccini GL, et al, “Effect of omega-3 fatty acids on rectal mucosal cell proliferation in subjects at risk for colon cancer”, Gastroenterology. 1992 Sep;103(3):883-91. 4. Huang YC, Jessup JM, Forse RA, Flickner S, Pleskow D, Anastopoulos HT, Ritter V, Blackburn GL, “n-3 fatty acids decrease colonic epithelial cell proliferation in high-risk bowel mucosa”, Lipids. 1996 Mar;31 Suppl:S313-7
