January 27, 2009
Omega 6 Fatty Acid Inflammation Risk Seen As Low

You can find lots of diet advice to balance your omega 6 fatty acid consumption with omega 3 fatty acids. The thinking is that omega 6 fatty acids increase inflammation and therefore cause heart disease and other health problems. However, an advisory published in Circulation: Journal of the American Heart Association argues that a higher omega 6 fatty acid diet will lower heart risk when omega 6 fatty acids replace saturated fats in the diet.

Linoleic acid (LA) is the main omega-6 fatty acid in foods, accounting for 85 percent to 90 percent of the dietary omega-6 PUFA.

There has been some debate within the nutrition community regarding the benefits of omega-6 based on the belief that they may promote inflammation, thus increasing cardiovascular risk. “That idea is based more on assumptions and extrapolations than on hard data,” said Harris, a research professor for the Sanford School of Medicine at the University of South Dakota and director of the Metabolism and Nutrition Research Center at Sanford Research/USD.

This advisory questions the belief that omega-6 fats increase inflammation.

The linking of omega-6 intake to inflammation stems from the fact that arachidonic acid (AA), which can be formed from LA, is involved in the early stages of inflammation. However, the advisory explains that AA and LA also give rise to anti-inflammatory molecules.

For example, in the cells that form the lining of blood vessels, omega-6 PUFA have anti-inflammatory properties, suppressing the production of adhesion molecules, chemokines and interleukins — all of which are key mediators of the atherosclerotic process. “Thus, it is incorrect to view the omega-6 fatty acids as ‘pro-inflammatory,’” Harris explained. “Eating less LA will not lower tissue levels of AA (the usual rationale for reducing LA intakes) because the body tightly regulates the synthesis of AA from LA.”

A meta-analysis of several trials finds that omega 6 polyunsaturated fatty acids (PUFAs) cut heart risks by a quarter.

In controlled trials in which researchers randomly assigned people to consume diets containing high versus low levels of omega-6 and then recorded the number of heart attacks over several years, those assigned to the higher omega-6 diets had less heart disease.

A meta-analysis of several trials indicated that replacing saturated fats with PUFA lowered risk for heart disease events by 24 percent. “When saturated fat in the diet is replaced by omega-6 PUFA, the blood cholesterol levels go down,” Harris said. “This may be part of the reason why higher omega-6 diets are heart-healthy.”

But would a diet where monounsaturated fats displaced the PUFAs cut heart risk even further?

Getting omega 3 fatty acids in your diet is still a good idea. Also, how you get your omega 6 fatty acids probably matters. For example, Nuts which are high in omega 6 also contain magnesium, vitamin E, and other beneficial nutrients. Whereas cooking oil delivers the omega 6 fats without as much of other nutrients.

Share |      Randall Parker, 2009 January 27 10:53 PM  Aging Diet Heart Studies

Lou Pagnucco said at January 28, 2009 8:56 AM:

This seems like a good study.

From my quick literature search, it seems that when omega-3 intake is adequate, omega-6 oils do not promote inflammation, and may actually lower it further.

With respect to omega-9 oils, you may want to read the abstract -

"Dietary intake of fatty acids and serum C-reactive protein in Japanese"

In Japanese with median intake of omega-3s, increasing dietary oleic acid and linoleic acid both decrease the inflammatory marker, C-reactive protein.

Tom Bri said at January 28, 2009 5:18 PM:

It is worth remembering though that a 24% difference, on a meta-analysis no less, is basically so little as to be meaningless. I would hazard a guess that most of those studies didn't reach the level of significance.

Evelyn Tribole, MS, RD/ Omega-6 Research News said at January 30, 2009 6:20 PM:

What is the American Heart Association’s Agenda? —It Sure Ain’t Science or Public Health

Controversy and debate are an expected (and welcome) part of the scientific process. But the American Heart Association’s recent advisory urging Americans to gobble up their omega-6 fat is an unconscionable disservice, to both the scientific process and the public health.

Old School Cholesterol Dogma versus Science
Here's the problem--AHA made sweeping statements that are not supported by the research, while ignoring landmark studies, which don’t support their views [Harris]. Read the studies and decide for yourself.

Here are links to some of the studies that refute AHA's claims:

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