Omega-6 versus Omega-3: linoleic acid promotes cancer development

Omega 6: abundance of linoleic acid promotes cancer development

A diet rich in linoleic acid, a well-known omega-6 fatty acid, can promote the growth of tumor masses. This was demonstrated in a study published in the pages of the British Journal of Cancer, the result of research by experts from the Laboratory of Molecular Carcinogenesis at the National Institutes of Health (Research Triangle Park, United States) and the Osaka City University Graduate School of Medicine (Osaka, Japan). According to the results obtained by the authors of the research, linoleic acid would promote cancer proliferation by promoting the formation within the neoplastic mass of new blood vessels, which ensure that the tumor is supplied with substances necessary for its growth. These results show that Omega-6s have an opposite action to that of Omega-3 fatty acids. Several studies have, in fact, shown the ability of the latter to counteract tumor growth.

A budgetary issue

Fatty acid intake through the diet is closely associated with the risk of developing various forms of cancer. Scientists have already in the past emphasized the importance of the balance between omega-6 and omega-3 fatty acids in counteracting the onset of cancer. In particular, years of research have shown that the probability of developing cancer is lower the more the ratio between the two types of fatty acids is unbalanced in favor of Omega-3. However, the typical diet of Western countries is increasingly rich in Omega-6s. Of these, the most abundant is precisely linoleic acid (LA).

Omega-6 and stomach cancers

The study published in the British Journal of Cancer focused on the role played by linoleic acid in different steps of stomach cancer development. The authors of the research chose two different model systems: laboratory-grown gastric carcinoma cells on the one hand, and animals on the other. By comparing gene expression between carcinoma cells treated with linoleic acid and untreated cells, the researchers identified factors potentially activated by the presence of Omega-6. The function of these genes was studied by analyzing their ability to promote several phenomena associated with cancer development:angiogenesis-that is, the process of forming new blood vessels,apoptosis-a form of cell death,cell invasion, degradation of material present between cells, and cell survival. It emerged that linoleic acid is able to activate the expression of a particular protein - plasminogen activator inhibitor 1 (PAI-1) - which, in turn, stimulates the invasion capacity of cancer cells. Not only that, the researchers also showed that activation of PAI-1 promoted by linoleic acid suppresses the activity of angiostatin, a protein that blocks angiogenesis. Consequently, in the presence of this omega-6 fatty acid, blood vessel production in the tumor is increased. Finally, experiments in animal models have shown that an increased introduction of linoleic acid through the diet promotes cancer growth.

Omega-6 and Omega-3, two opposing actions against cancer

Based on these findings, the study authors concluded that, in contrast to Omega-3, Omega-6 and, in particular, linoleic acid may promote several steps determining cancer invasion capabilities and blood vessel formation in the tumor mass. Therefore, the researchers hypothesize that reducing the amount of linoleic acid introduced through the diet could help reduce disease progression.

Source 

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