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Misleading Headlines Distort Meaning of Research on Fish and Heart Rhythms
5/26/2006
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Confirmation of heart benefits lost in media's focus on a minor caveat 
by Craig Weatherby 


Based on the media's past behavior, we’re beginning to think that if new research came along that confirmed bountiful health benefits from eating bananas, the resulting headlines would proclaim, “Bananas Called Cause of Potentially Dangerous Pratfalls,” with the 98-percent positive findings buried in the body of the article. 
 

And that’s pretty much how the media handled new research concerning links between dietary fish and the rate at which men develop one relatively benign kind of irregular heart rhythm.


Key Points

  • Misleading media headlines distort heart-rhythm/omega-3 results.
  • A new analysis of data from the Physicians' Health Study indicates a correlation between higher fish intake (five or more meals per week) and a 55 percent increase in risk of one kind of heart rhythm abnormality (atrial fibrillation).
  • The observed correlation does not prove a cause-and-effect relationship between extraordinarily high fish intake and a slightly increased risk of developing atrial fibrillation.
  • The study authors and expert commentators agree that the observed correlation could stem from other lifestyle attributes of the participants who ate the most fish.

If researchers agree on only one thing about the omega-3s in fish and fish oil, it is that they reduce the risk of sudden cardiac death from heart attacks and strokes, in large part by helping your heart keep a steadier, safer beat.

 

In fact, the heartbeat-normalizing effect of omega-3s explains much of the reduction in heart-attack risk attributed to eating fish.

 

But at a time when the mantra of the media has become “if it bleeds it leads”, news outlets prefer negative headlines that
counter conventional wisdom. This is why virtually all of the news stories that related the results of a new analysis of prior research data focused on the one negative finding amid an overwhelmingly positive report.

 

If this knee-jerk impulse to highlight the negative didn’t run the risk of cutting people’s fish consumption—a truly dangerous outcome—the misleading headlines on most of the stories that reported on the new analysis wouldn’t warrant comment.

 

Since the media's fact-distorting headlines do pose this risk, it's important that people get a more accurate, balanced picture of the new analysis, which only confirms the value of fish and fish oil for preventing sudden death from heart attacks and stroke.

 

What the new study showed

Earlier this month, researchers from New York University Medical Center attended the 27th annual meeting of the Heart Rhythm Society and presented their new analysis of data from the famed Physicians' Health Study.  

 

The Physicians' Health Study is a “cohort” investigation, in which researchers follow a defined group of volunteers over time, periodically asking questions about behavior and diet, in order to discover any connections between these lifestyle factors and health outcomes.

 

This landmark study, which began in the fall of 1982, was initially designed to test the benefits and risks of aspirin and beta-carotene in the prevention of cardiovascular disease and cancer. The study is still in progress 23 years and more than 200 published research reports later, with more to come.

 

The NYU researchers who presented the new analysis examined data collected from a sub-group of 17,679 doctors participating in the Physicians' Health Study. Data from these particular doctors was selected because they were not taking omega-3 (fish oil) supplements, which allowed the NYU analysts to isolate the effects of fish consumption on heart health.

 

The physicians whose data was selected by the NYU team had answered questions about their fish consumption in 1983, and were asked in 1998 whether they’d developed the type of irregular heart beat called atrial fibrillation.


The Bottom Line


The authors of the new study emphasize that the protective benefits of fish consumption against sudden cardiac death still far outweigh the theoretical increased risk of atrial fibrillation, a kind of arrhythmia (abnormal heart rhythm) considered much less serious. Ventricular fibrillation is a leading immediate cause of Sudden Cardiac Death: the common kind of fatal cardiac event that fish is proven to help prevent

When the NYU team analyzed the data, it appeared that men who ate fish more than five times a week were 55 percent more likely to develop atrial fibrillation, compared to those who ate fish once a month.

 

(Note: Most of the media reports cite a 61 percent greater risk, but this number is not found in the study abstract published on the Heart Rhythm Society’s Web site. We suspect that an early news report got it wrong, and that other media outlets repeated the error.)

 

The physicians who ate fish once a month or less had no increased risk, whereas men who ate fish two to four times a week had a 41 percent greater risk of developing atrial fibrillation.

 

When the investigators controlled for possible confounding factors—including cardiovascular-disease risk and lifestyle factors, as well as aspirin or beta-carotene use—they found that men in the two highest fish-consumption categories had a 32 percent or 46 percent greater risk of developing atrial fibrillation, respectively.

 

NYU team confirms that fish is strongly heart-protective

You’d think, based on most media reports, that the new analysis suggests people shouldn’t eat fish more than once a week, but nothing could be further from the truth.

 

As lead author Dr. Anthony Aizer said (key point underlined), "It is important to recognize that within the same population as this current study, fish consumption was associated with lower risk of sudden cardiac death, which is the result of a much more life-threatening cardiac arrhythmia, ventricular fibrillation."

 

And Dr. Aizer also noted that the protective benefits of fish consumption still far outweigh the hypothetical increased risk of atrial fibrillation: "The message of this study is not to stop eating fish. Atrial fibrillation is a complex condition that requires the interaction of a number of factors to develop. Fish may have different effects on different people. Lifestyle and dietary habits need to be tailored on an individual basis to promote overall health."

 

It is important to note that the method of cooking plays a powerful part in the ability of fish to protect cardiac health. Harvard researchers who analyzed data from the Cardiovascular Health Study—which involved 4,815 people ages 65 years and older—found that eating mostly batter-crusted fried fish (high in inflammatory omega-6 fats) increases cardiac risk, and eating mostly baked or broiled fish reduces the risks (Mozaffarian D 2003).

 

While the participants in the Physicians' Health Study answered a four-item questionnaire that asked about the frequency of fish consumption and the type consumed (e.g., canned tuna, dark meat fish such as mackerel or bluefish, crustaceans, or other fish), it did not ask about cooking method, so it is impossible to know whether this played a part in the increased risk of atrial fibrillation.

 

Bottom line: keep eating fish frequently

As we’ve said, Dr. Aizer points out that among all of the men participating in the Physicians' Health Study fish consumption was associated with lower risk of ventricular fibrillation and sudden cardiac death.

 

He also noted that the Physicians' Health Study wasn’t a double-blind, placebo-controlled clinical trial, which leaves open the possibility that another, unknown factor could account for the rise in atrial fibrillation (AF) cases.

 

Dr. Marie-Noelle Langan, chief of electrophysiology at Lenox Hill Hospital in New York City noted the strong possibility that the male doctors who ate a lot of fish each week did so because they were health-minded, and therefore also more likely to exercise.

 

As she said, "It's possible this is a group of very fit people who run like maniacs. It doesn't take that many patients to throw off the statistics."

 

 

Sources

·         Aizer A, Gaziano M, MansonJE, Buring JE, Albert CM. Relationship between fish consumption and the development of atrial fibrillation in men. Oral Abstract Sessions AB03, Abstract AB03-2, presented at the 27th annual meeting of the Heart Rhythm Society, Thursday, May 18, 2006, BostonUSA

·         Calo L, Bianconi L, Colivicchi F, Lamberti F, Loricchio ML, de Ruvo E, Meo A, Pandozi C, Staibano M, Santini M. N-3 Fatty acids for the prevention of atrial fibrillation after coronary artery bypass surgery: a randomized, controlled trial. J Am Coll Cardiol. 2005 May 17;45(10):1723-8. 

·         Mozaffarian D, Longstreth WT Jr, Lemaitre RN, Manolio TA, Kuller LH, Burke GL, Siscovick DS. Fish consumption and stroke risk in elderly individuals: the cardiovascular health study. Arch Intern Med. 2005 Jan 24;165(2):200-6. Erratum in: Arch Intern Med. 2005 Mar 28;165(6):683.

·         Mozaffarian D, Psaty BM, Rimm EB, Lemaitre RN, Burke GL, Lyles MF, Lefkowitz D, Siscovick DS. Fish intake and risk of incident atrial fibrillation. Circulation. 2004 Jul 27;110(4):368-73. Epub 2004 Jul 19.

·         Mozaffarian D, Lemaitre RN, Kuller LH, Burke GL, Tracy RP, Siscovick DS; Cardiovascular Health Study. Cardiac benefits of fish consumption may depend on the type of fish meal consumed: the Cardiovascular Health Study. Circulation. 2003 Mar 18;107(10):1372-7.

·         Mozaffarian D, Bryson CL, Lemaitre RN, Burke GL, Siscovick DS. Fish intake and risk of incident heart failure. J Am Coll Cardiol. 2005 Jun 21;45(12):2015-21.

·         Frost L, Vestergaard P. n-3 Fatty acids consumed from fish and risk of atrial fibrillation or flutter: the Danish Diet, Cancer, and Health Study. Am J Clin Nutr. 2005 Jan;81(1):50-4. 

 

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