American Heart Association Panel Finds No Evidence That Omega-6 Fatty Acids Raise Heart Risk
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Reviewed By Louise Chang, MD
Jan. 26, 2008 -- The American Heart Association (AHA) has come to the defense of omega-6 fatty acids, the fats found in many grains and most vegetable oils that some have linked to heart disease.
In a scientific advisory released today, an AHA panel noted that there is little credible evidence that omega-6 fatty acids promote inflammation and increase cardiovascular risk.
The experts concluded that reducing omega-6 polyunsaturated fatty acids (PUFAs) from their current levels would be more likely to increase the typical American's risk for heart disease than decrease it.
"Our goal was simply to let Americans know that foods containing omega-6 fatty acids can be part of a healthy diet, and can even help improve your cardiovascular risk profile," researcher and panel chairman William S. Harris, PhD, notes in a news release.
Good Fat, Bad Fat?
Harris tells WebMD that the advisory was issued to clear up confusion about omega-6, which has been cast as a dietary villain by some in the nutrition community.
Barry Sears, PhD, who created the Zone Diet, is the most well-known proponent of the idea that dietary omega-6 fatty acids promote inflammation and heart disease.
In his latest book, Sears claims that heart disease and many other chronic diseases can largely be blamed on the fact that the Western diet contains too much omega-6 and not enough omega-3, the fat found primarily in salmon and other fatty fish.
He argues that high-carbohydrate diets that contain high levels of omega-6-rich grains and vegetable oils promote chronic disease by producing the inflammatory arachidonic acid (AA).
But Harris says there is no proof that omega-6 from vegetable sources promotes inflammation and plenty of evidence that eating grains and vegetable oils protects the heart.
The AHA panel reviewed the scientific evidence examining the impact of omega-6 PUFAs on the risk of heart and cardiovascular disease.
Their analysis of more than two dozen studies reveals that:
- People in observational studies who ate the most omega-6 fatty acids typically had lower rates of heart disease than people who ate the least.
- Patients with heart disease tended to have lower levels of omega-6 in their blood than people without the disease.
- People in controlled trials who ate diets high in omega-6 were less likely to develop heart disease than those who ate diets that were low in omega-6.
The panel report notes that the advice to reduce omega-6 PUFA intake is typically framed as a call to lower the ratio of dietary omega-6 to omega-3 PUFAs.
"Although increasing omega-3 PUFA tissue levels does reduce the risk of chronic heart disease, it does not follow that decreasing omega-6 levels will do the same," panel members write in the Feb. 17 issue of the AHA journal Circulation. "Indeed, the evidence considered here suggests that it would have the opposite effect."
The AHA recommends eating a diet that includes plenty of fruits, vegetables, high-fiber whole grains, lean meats, poultry, and at least two servings of fish a week.
The panel recommended that 5% to 10% of calories come from omega-6 fatty acids, and Harris says most Americans get it about right. The main omega-6 fatty acid obtained from diet is linoleic acid, which mainly comes from vegetable oils such as safflower, corn, and sunflower.
Instead of focusing on omega-6, Harris says people who want to reduce their heart disease risk should strive to lower their intake of saturated fats from fatty and processed meats and increase the omega 3-fatty acids in their diet by eating fish or taking fish oil supplements.
"Omega-6 fatty acids are not the villains," he says. "These are good fats that are important for cardiovascular health."
AHA past president Robert Eckel, MD, agrees that the analysis does not support the claim that omega-6 PUFAs promote inflammation. Eckel is a professor of medicine at the University of Colorado in Denver.
"The evidence is overwhelming to indicate that diets higher in vegetable oils and lower in saturated fats and trans fats are heart healthy," he tells WebMD. "This needs to be emphasized to counter recent claims that eating vegetable oils is harmful."
SOURCES: Harris, W.S. Circulation, Feb. 17, 2009; online edition. William S. Harris, PhD, FAHA, research professor, Sanford School of Medicine, University of South Dakota; director, Metabolism and Nutrition Research Center, Sanford Research/USD. Robert H. Eckel, MD, professor of medicine, division of endocrinology, metabolism and diabetes and cardiology, University of Colorado, Denver; past president, American Heart Association.
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