Heart-Healthy Diet

Your Rhythm Section

You don’t need to know a single thing about heart health to know that you don’t want to see the word “abnormal” in a sentence about heart rhythm. But a new study confirms that when a certain food is frequently eaten, you may be able to keep the word “abnormal” out of any discussion about your heart muscle contractions.

On the QT

An electrocardiogram (ECG) measures the rhythmic beating of your heart by giving your doctor several different views of your heart’s electrical activity. This highly complex process can be simplified to the “QT interval”: The Q wave starts off the electrical cycle, and the T wave ends it. The QT interval is the brief moment between the Q wave and the T wave.

In a new study from the University of Athens School of Medicine in Athens, Greece, researchers assessed heart health by comparing differences in QT intervals (QT scores) to dietary intake. A high QT score can reveal the risk of arrhythmia – a disturbance of the heart’s rhythm. Types of arrhythmias range from simple irregularities, which are not dangerous, to more pronounced abnormalities, which can prompt heart attacks and strokes.

STUDY PROFILE

• Researchers drafted more than 3,000 subjects, evenly divided between men and women, with an average age of 45
• Each subject was given an ECG and completed a food-frequency questionnaire that rated weekly intake of more than 150 different food items
• Data analysis revealed that subjects who ate more than 10.5 ounces of fish each week had significantly lower QT scores compared to subjects who never ate fish
• Higher QT scores indicate a high resting heart rate, which has been associated with an increased risk of cardiovascular mortality, even when other risk factors are not present.
• The Athens researchers believe that a steady diet of fish (which supplies ample omega-3 fatty acids) may help support the electrical function in heart muscle cells.

Cooking good

All of the subjects in the University of Athens study lived in Greece. In other words, many of them (perhaps most of them) followed a typical Mediterranean diet, which is widely recognized as a heart-healthy diet.

So what about someone in the U.S. who has a high fish intake? Will they reap the same benefits?

A possible answer to that question can be found in the results of a 2004 study from Harvard Medical School. When researchers examined 12 years of electrocardiograms and dietary data for more than 4,800 people over the age of 65, they found that regular consumption of tuna or broiled or baked fish was clearly associated with a lower incidence of atrial fibrillation (AF), the most common type of abnormal heart rhythm.

For subjects who ate fish five or more times each week, risk of AF was reduced by 35 percent, compared to subjects who ate fish less than once a month.

In the published study the authors wrote: “Consumption of tuna and other broiled or baked fish correlated with plasma phospholipid long-chain n-3 fatty acids, whereas consumption of fried fish or fish sandwiches (fish burgers) did not.”

In fact, fried fish can actually be quite harmful. In the e-Alert “David Beats Goliath Again” (5/15/03), I told you about a University of Washington study that demonstrated how a regular intake of fried fish might produce a higher risk of both heart attack and death.