Study Reveals How Fish Oils Help the Heart
They contribute to better regulation of electrical activity
MONDAY, July 24, 2006 (HealthDay News) -- For older adults, fish oils help the heart by regulating its electrical activity, a new study indicates.
And just a couple of meals a week of the right kind of fish -- rich in omega-3 fatty acids, baked or boiled, but not fried -- will do the job, according to the report in the Aug. 1 Journal of the American College of Cardiology.
The finding "supports studies suggesting that fish intake reduces the risk of sudden death," said study lead author Dr. Dariush Mozaffarian, a cardiologist and instructor of medicine at Brigham and Women's Hospital, in Boston.
It has long been known that eating fish such as tuna, mackerel, lake trout and salmon, which are rich in omega-3 fatty acids, is good for the heart. Mozaffarian and his colleagues set out to discover why.
They analyzed data from more than 5,000 men and women aged 65 and older in the federally funded Cardiovascular Heart Study. The participants were asked whether they ate fish, what kind, and how often. The researchers compared the answers to those dietary questions with electrocardiogram tests of the study participants.
What they found was that eating fish was associated with a lower heart rate, a slower interval between when the heart received a signal to pump blood and when blood was pumped, and a lower likelihood that the heart would take a long time to reset its electrical system after a beat.
That last effect is important, Mozaffarian said. "The heart resets its electrical activity after every beat," he said. "When there is heart disease, the resetting can be delayed. That is dangerous."
Animal studies have indicated why the omega-3 fatty oils confer their beneficial effect, Mozaffarian said. "The fish oils get into the membrane of heart cells and affect the function of their protein channels," he said. "Potassium, sodium and calcium pass through those channels, controlling the whole electrical cycle."
While the new study found that the more fish consumed, the greater the benefits, most gains were achieved with just one or two meals of fish a week. That was especially true for the lower heart rate, Mozaffarian said.
But it had to be the right kind of fish, and prepared the right way. No effect on the heart's electrical activity was seen with fried fish, such as fish burgers or fish sticks. Those commercial products do not increase blood levels of omega-3 fatty acids.
And people who think they can take a shortcut by using fish-oil supplements are mistaken, said Alice H. Lichtenstein, professor of public health and family medicine at Tufts University School of Medicine, and a spokeswoman for the American Heart Association.
"Recent studies have cast doubt on the belief that fish-oil supplements are beneficial," Lichtenstein said.
The latest recommendations on omega-3 fatty acids are available from the American Heart Association.