The benefits of fish without the fish?

(CNN) -- Researchers have come up with another reason to take fish to heart.

An Italian study suggests fish-oil supplements may dramatically reduce the risk of sudden death in heart attack survivors.

"I think one can't make an absolute judgment on the basis of one study," said Dr. Alice H. Lichtenstein, a nutrition professor at Tufts University and vice president of the American Heart Association's nutrition committee. "However, this certainly is a major contribution to the body of data that's currently available."

The GISSI-Prevenzione study, results of which appear in the April 9 issue of Circulation, the Journal of the American Heart Association, determined that a daily gram of n-3 polyunsaturated fatty acids reduced the risk of sudden death and death overall in people who have had heart attacks.

The study involved more than 11,300 participants, about one-fourth of whom received 1 gram each day of n-3 polyunsaturated fatty acids. A second group took 300 milligrams of vitamin E each day, another took both, and a fourth group took a placebo.

Although study participants already benefited from a diet rich in fruits, vegetables, olive oil and fish, researchers noted that those who received the supplements had fewer sudden deaths than those who didn't.

The fatty acids, also known as omega-3 fatty acids, are found in fish such as salmon, tuna, mackerel, lake trout and sardines.

Experts said they believe the fatty acids help reduce episodes of arrhythmia, or irregular heartbeats, which are a major cause of death from coronary heart disease.

Despite the promising results, the American Heart Association doesn't endorse fish oil supplements at this point, noting that it needs more compelling evidence of their benefits.

Lichtenstein agrees.

"I personally am not willing to say at this point that supplements are a good substitute for fish," she said.

Instead, the heart association favors a healthy diet that includes fish.

"As a cardiologist, I generally recommend having fish at least one to two times a week," said Dr. Ramin Farshi of Los Angeles, California. "And of course, we advise having a lower fat intake -- that's a given."

-- CNN.com writer Greg Botelho contributed to this story.