Fish and Fish Oil Prevent Abnormal Heart Rhythms

Eating fatty fish, such as salmon, tuna, mackerel, and cod, and supplementing with fish oil both reduce the risk of developing abnormal heart rhythms (arrhythmias), according to two recent studies (Circulation 2004;110:368–73 and Prostaglandins, Leukotrienes, and Essential Fatty Acids 2004;71:153–9).

Ample evidence has already shown that eating fatty fish and supplementing with fish oil can reduce heart-attack risk. One study found that eating fatty fish regularly reduces the risk of fatal heart attack by 50%. Several others have also found that people getting high amounts of the fats from fish have a lower likelihood of sudden heart-related death. Eating fish can improve the function of the heart muscle, prevent clots from forming and blocking the blood vessels of the heart, and reduce blood pressure and inflammation. Recent evidence suggests that these fats might also prevent dangerous abnormalities in heart rhythm.

A healthy heart’s rhythm is regulated by electrical signals to the heart muscle that come from a single point within the heart. When signals from this point come in abnormally rapid succession, or when signals come from other places in the heart, they disrupt the normal rhythm and cause arrhythmias. Some severe types of arrhythmia can lead to heart attack, stroke, or sudden death.

In the first of the new studies, 65 people with arrhythmia were randomly assigned to receive either 3 grams of fish oil (providing 1 gram of omega-3 fatty acids) per day or placebo for six months. Blood tests were performed and heart rhythms were assessed during the six-month trial and for six months after stopping the supplements.

Compared with the beginning of the study, people receiving fish oil had significantly fewer and less severe arrhythmias. People taking fish oil had 46.9%, 67.8%, 71.8%, and 100% fewer occurrences of the four types of arrhythmia monitored in this study (atrial premature complexes, ventricular premature complexes, couplets, and triplets). Six months after stopping the fish oil, these improvements were reversed and all measurements were similar to those from the beginning of the study. People receiving placebo experienced no significant changes in arrhythmia frequency during the study.

In the other study, 4,815 people over the age of 65 years were given food questionnaires at the beginning of the study. The participants were monitored for a potentially serious type of arrhythmia known as atrial fibrillation. They were followed for 12 years through annual physical exams and electrocardiographs to assess heart rhythms, and through reviewing records from all hospital visits.

Frequent fish eaters were found to have a lower risk of developing atrial fibrillation than people who were not. Compared with eating fish less than once per month, eating fish one to three times per month was linked to a 24% reduction in risk of atrial fibrillation, eating fish one to four times per week was linked to a 30% reduction in risk, and eating fish five or more times per week reduced the risk by 35%. Frequently eating fried fish and fish sandwiches increased, rather than decreased, risk of atrial fibrillation.

The results of these studies add to the evidence that fats from fish might reduce the risk of arrhythmias that can lead to heart attack, stroke, or sudden death. In elderly people, eating fatty fish reduced the risk of atrial fibrillation, and in people with existing arrhythmias, supplementing with fish oil reduced the number and severity of episodes of arrhythmia. These findings taken together suggest another way in which fats from fish might lower the risk of heart attack.

Maureen Williams, ND, received her bachelor’s degree from the University of Pennsylvania and her Doctorate of Naturopathic Medicine from Bastyr University in Seattle, WA. She has a private practice in Quechee, VT, and does extensive work with traditional herbal medicine in Guatemala and Honduras. Dr. Williams is a regular contributor to Healthnotes Newswire.

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