Considerable research has shown that the omega-3 fats, found in fish oils, can reduce inflammation, decrease blood pressure, prevent arrhythmias, and lower the risk of heart attack. Now, researchers have reported that diets high in omega-3 fish oils can also protect against a particular genetic predisposition for heart disease.
James H. Dwyer, PhD, of the University of Southern California, Los Angeles, and his colleagues investigated variations in the ALOX5 gene. This gene programs the construction of 5-lipoxygenase, an enzyme involved in making inflammation-promoting molecules.
Dwyer identified ALOX5 genetic variations in 6 percent of a group of 479 healthy middle-age men and women living in the Los Angeles area. Having a variation in the ALOX5 gene increased the risk of blood vessel narrowing, a sign of heart disease. The ALOX5 was also associated with substantially higher levels of C-reactive protein, a marker of inflammation and a risk factor for heart disease.
But much of the risk of heart disease posed by the ALOX5 variations was either amplified or mitigated by diet. People who ate diets rich in omega-6 fats, specifically linoleic acid and arachidonic acid (found in corn, safflower, soy, and other cooking oils), were far more likely to have narrowed arteries and higher levels of inflammation.
However, people who consumed large amounts of omega-3 fish oils, specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), had no increased risk of heart disease or inflammation.
Dwyer and his colleagues explained that omega-6 and omega-3 fats compete with each other to use the 5-lipoxygenase enzyme. Increasing consumption of omega-3 fats reduces the production of pro-inflammatory omega-6 molecules, which are involved in heart disease.
REFERENCE
Dwyer JH, Allayee H, Dwyer KM, et al. Arachidonate 5-lipoxygenase promoter genotype, dietary arachidonic acid, and atherosclerosis. New England Journal of Medicine, 2004;350:29-37.