Which Fats Really Are Good for Your Heart?

Feb. 6, 2013 -- The standard advice about which fats are best for heart health is under debate again.

Triggering it is new research, just published in BMJ, finding that a form of omega-6 fatty acid found in vegetable oils may actually boost heart disease risk. Omega-6 fatty acids are a type of polyunsatured fat, which has generally been considered heart healthy.

The new findings could significantly alter the advice about which type of fats to eat, some experts say. The new research warrants another look at the current recommendations, says a spokesperson for the American Heart Association.

WebMD turned to the study author and other experts to sort out the findings -- and to figure out which fats to eat now.

First, a refresher course on fats:

Saturated fats, found in high-fat dairy, meats, and fried foods, as well as trans-fats, found in processed foods such as chips and cookies, should be limited. Experts agree they raise the risk of heart disease.Unsaturated fats, in moderation, are considered heart-healthy, overall. These include monounsaturated fats and polyunsaturated. Monounsaturated fats are found in olive oil, nuts, and other foods. Polyunsaturated fats can be broken down into two types: omega-6 fatty acids, found in soybean oil, corn oil, and safflower oil; and omega-3 fatty acids, also in soybean and canola oil and in nuts and some fish as well.

What's the ''back story'' on omega-6 fatty acids?

While polyunsaturated fatty acids -- which include omega-3 and omega-6 fatty acids -- are viewed as heart-healthier fats, the information about the benefits of omega-6 fatty acids is more limited, says Christopher Ramsden, MD, a clinical investigator at the National Institutes of Health. He led the research.

Because many oils often contain both, it has been difficult to know which is healthier than the other.

The benefits of foods with both omega-3 and omega-6 fatty acids (such as many vegetable oils)  may be due more to the omega-3 fatty acids, says Ramsden. "We suspect that omega-6 might not be as healthy as omega-3," he says.

Different fatty acids may have different effects on heart health, he says.

What exactly did the study look at?

Ramsden and his team recovered some unanalyzed data from the Sydney Diet Heart Study, conducted from 1966 to 1973. The study included 458 men, ages 30 to 59, with a history of heart attack or other heart problems.

One group was told to reduce their saturated fat intake to less than 10% of daily calories and increase their polyunsaturated fat intake to about 15% of calories. They were told to use safflower oil or safflower oil margarine, which has linoleic acid, a form of omega-6, but no omega-3 fats.

The other group received no specific instruction on diet.

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