Consumers who want to take advantage of the cardiac benefits of fish oil supplements but were concerned about possible mercury and PCB contamination can pop their pills in peace.

ConsumerLab.com, which evaluates nutritional and health supplements, found that of 41 fish oil supplements tested, none were contaminated with mercury or PCBs.

Omega-3 supplements generally are made from fish oil, although they can be derived from algae. In fish-oil-based pills, the oil is distilled to filter out contaminants. Also, the fish used to make pills tend to be younger and smaller than the fish consumers eat, meaning it has had less time to accumulate toxins.

"With all the news this year with mercury in this fish and dioxins or PCBs in that fish, people were concerned. So it put to rest in our minds the issue of purity," says ConsumerLab.com president Tod Cooperman.

Mounting evidence suggests a diet that includes plenty of omega-3-rich fatty fish such as mackerel, lake trout, herring, salmon, sardines and albacore tuna can reduce the risk of fatal heart attacks.

"If you eat fish at least once or twice a week, you can cut your risk of dying (suddenly) by 30%, and it seems to be true as well for fish oil pills," says David Schardt, a senior nutritionist with the Center for Science in the Public Interest.

The American Heart Association (AHA) dietary guidelines suggest that for people without known coronary heart disease, at least two meals a week include such fish. For people with coronary disease, 1g a day of omega-3 is recommended, approximately a serving of fatty fish a day. A teaspoon of cod liver oil also would do it.

"It's pretty dang hard to get that much" from eating fish in meals, says William Harris, a University of Missouri-Kansas City professor who helped write the AHA guidelines.

Supplements can help people get enough omega-3 fatty acids, Harris says. "If you just left it to 'You've got to eat a pound of salmon a day,' then most people couldn't do it."

The ConsumerLab.com tests, together with recent tests by Consumer Reports magazine, indicate those wanting to take the supplements have no reason for concern. "With all the mounting evidence in favor of fish oil, it's very good news. If people are concerned about contamination, especially pregnant women, the supplements seem quite safe," Cooperman says.

Testing did find some product-integrity issues with two brands not containing as much omega-3 as claimed. A full listing is at www.consumerlab.com.