Background: A potent class of eicosanoids called leukotrienes is a known trigger of asthma and is associated with atherosclerosis. Leukotrienes are made in the body from the omega-6 fat, Arachidonic acid.    The enzyme that triggers this powerful inflammation cascade is 5-lipoxygenase (or LOX for short).

Since atherosclerosis involves inflammation, the researchers hypothesized that people who have the gene that makes more of the LOX enzyme, would be at an increase risk of atherosclerosis, which could be modifiable by diet. In short, yes.  The findings are compelling:

     • Both omega-6 fats, linoleic acid and arachidonic acid, were significantly associated with increased severity of atherosclerosis.

     • Omega-3 fats (EPA and DHA) were beneficial and blunted the atherogenic effect triggered by the LOX inflammation cascade.

Study Conclusion: “The observed diet–gene interactions further suggest that dietary n–6 polyunsaturated fatty acids promote, whereas marine n–3 fatty acids inhibit, leukotrienes-mediated inflammation that leads to atherosclerosis in this subpopulation.”

Comment: The people in the study were eating a typical American diet (high in omega-6 fats). Keep in mind that for years, heart patients have been advised to increase their polyunsaturated fats, which are synonymous with omega-6 fat. Consequently, this advice increases dietary omega-6 fat intake. (which are found in soybean oil, corn oil, cottonseed oil, sunflower oil and safflower oil). These are the key oils used in margarines, mayonnaise, salad dressings and processed foods.

Free Full Text Link:
Dwyer, James H et al. Arachidonate 5-Lipoxygenase Promoter Genotype, Dietary Arachidonic Acid, and Atherosclerosis N Engl J Med 2004 350: 29-37