Eating tuna or other broiled or baked fish appears to have a beneficial effect on the electrical system of the heart, which may help prevent life-threatening heart rhythm disorders, according to a new report.

Previous reports have linked fish intake with a reduced risk of sudden death and irregular heart beats, but the mechanisms responsible for this association were unknown. However, evidence from animal studies has suggested a direct effect from fish oil intake on the hearts electrical circuitry.

As reported in the Journal of the American College of Cardiology, Dr. Dariush Mozaffarian, of Harvard Medical School, Boston, and colleagues analyzed data from 5096 adults enrolled in the Cardiovascular Health Study to investigate the link between dietary intake of fish n-3 fatty acid and features seen on electrocardiograms.

The population-based study, which focused on cardiovascular disease risk factors, ran from 1989 to 1990 and involved subjects who were at least 65 years of age.

Intake of tuna or other broiled or baked fish at least once a week was associated with a slower heart rate than was eating these fish less than once a month.

Moreover, fish intake at least five times per week was associated with an even healthier heart rhythm. Consumption of marine n-3 fatty acids appeared to have similar effects.

Intake of fried fish was not associated with any ECG changes.

"Previously," Mozaffarian said in a statement, "we have seen that intake of fried fish -- which in the US are most often commercially sold fish burgers or fish sticks -- is not associated with blood levels of n-3 fatty acids. This suggests that it may be the n-3 fatty acids in tuna and other broiled or baked fish that are having a positive impact on the heart's electrical parameters."