WEDNESDAY, Oct. 22, 2014 (HealthDay News) -- Over the last three decades, Americans have cut their intake of artery-clogging saturated and trans fats -- but not enough, new research shows.

Meanwhile, consumption of healthy omega-3 fatty acids known as DHA and EPA -- plentiful in fatty fish like salmon -- has remained steady, though very low, the experts found.

"These trends are encouraging, but we still have room for improvement in our diet," said Mary Ann Honors, a post-doctoral research fellow at the University of Minnesota, Minneapolis.

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Both saturated and trans fats increase heart disease risk, by mechanisms such as raising so-called "bad" cholesterol (LDL) and lowering "good" cholesterol (HDL), according to the American Heart Association (AHA).

Saturated fats are found in meats, full-fat dairy foods and some oils, such as coconut and palm, according to the AHA.

Trans fats are found in baked goods such as pizzas, cookies and pies, the AHA says. However, food makers have reformulated products in the last few years to reduce or eliminate trans fats. Effective in 2006, the U.S. Food and Drug Administration required trans fats to be listed on the nutrition label of foods.

Products can carry a label saying "no trans fats" if the item has less than 0.5 grams per serving, according to the FDA.

Honors and her colleagues looked at six surveys done as part of the Minnesota Heart Survey from 1980 to 2009. The surveys polled more than 12,000 adults, aged 25 to 74, who lived in the Minneapolis-St. Paul area.

The investigators found that trans fat intake dropped by about one-third in men and women over the nearly 30-year study period.

However, men still ate about 1.9 percent of calories daily from trans fats and women ate about 1.7 percent. Ideally, the AHA recommends limiting trans fats to no more than 1 percent of calories consumed.

For a typical 2,000-calorie a day diet, Honors said, 1 percent would be about 20 calories or 2 grams of trans fats.

Saturated fat intake dropped, too, but still accounted for about 11 percent of daily calories for both men and women during 2007 to 2009, Honors found. The American Heart Association recommends limiting saturated fats to about 5 or 6 percent of total calories.

Omega-3 fats can help heart health, but intake was a fraction of what is recommended, both for men and women, the researchers found.

"The recommendation is 0.25 grams or 250 milligrams of DHA and EPA, two common omega-3s, per day," she said. Between 2007 and 2009, both men and women took in just 0.08 grams of DHA and 0.04 of EPA. She recommends getting omega-3s from two or more servings a week of fish like mackerel and salmon, rather than a fish oil capsule.

The study findings are no surprise, said Connie Diekman, director of university nutrition at Washington University in St. Louis. "Achieving lower intakes of saturated fats requires shifting calories to more plant food,'' she said, ''and one way to do this is consuming more fruits and vegetables, something we also fail to consume."

Most people find it difficult to eat enough fish to take in enough omega-3, she said, and some may not have access to enough.

Diekman said that trans fats in products will continue to decline as products change. "So that issue is not likely as big of a concern as saturated fats and the omega-3s," she said.

The study was published online Oct. 22 in the Journal of the American Heart Association.

More information

To learn more about dietary fats, visit the American Heart Association.