New York, Jan 27 - Americans should not reduce their consumption of omega-6 fatty acids, and might even benefit from eating a little more, according to the American Heart Association.
Omega-6 and omega-3 fatty acids are "essential fats" that the body can't produce and must obtain from food. These fatty acids play a very important role in heart and brain function, along with normal growth and development.
Most omega-6 polyunsaturated fatty acids (PUFAs) in the diet come from linoleic acid, found in vegetable oils such as corn oil, Dr. William S. Harris of the Sanford School of Medicine at the University of South Dakota in Vermillion and his colleagues explain in their report, published in the journal Circulation. Omega-3 fatty acids are found in fatty fish such as tuna, salmon and mackerel and flax seed.
There are no firm recommendations on how much omega-6 PUFAs people need, Harris and his team add, but at present U.S. adults consume about 15 grams per day of linoleic acid, or 6.7 percent of their total calorie intake. According to the Institute of Medicine, 17 grams per day and 12 grams a day are adequate for men and women, respectively, representing 5 percent to 6 percent of total calories.
Questions have been raised about whether omega-6 PUFAs might harm the heart by promoting inflammation, because these fatty acids are the building blocks of several types of inflammatory molecules, the researchers note. But most scientific evidence suggests omega-6 fatty acids actually reduce inflammation, they add, and the nutrients also have "well-documented" effects in lowering cholesterol levels.
Clinical trials in humans also suggest that replacing calories from saturated fats or refined carbohydrates with omega-6 fatty acids also reduce heart disease risk, Harris and his colleagues say.
While some investigators have suggested reducing the ratio of omega-6 fatty acids to omega-3 fatty acids by eating less omega-6 could be beneficial, the researchers argue that focusing on this ratio has "conceptual and biological limitations," especially if it leads to people cutting their consumption of omega-6 fatty acids rather than increasing their omega-3 intake.
Based on their review of evidence from studies in humans and animals, the researchers conclude that getting up to 10 percent of one's calories from omega-6 fatty acids is safe and reduces heart disease risk compared with lower intakes.
"In summary, the AHA supports an omega-6 PUFA intake of at least 5 percent to 10 percent of energy in the context of other AHA lifestyle and dietary recommendations," they write. "To reduce omega-6 PUFA intakes from their current levels would be more likely to increase than to decrease risk for coronary heart disease."