Dietary benefits of fish

Big Fish

Confusion about healthcare often exceeds actual information about healthcare in the mainstream media Tower of Babel. And when a cockamamie study comes along and receives media attention, the roar of confusion just grows louder.

So let’s get one thing straight right here: For the vast majority of humans, omega-3 fatty acids found in fish will do their hearts a world of good. But if we’re to believe a new study, too much fish consumption may raise the risk of atrial fibrillation (AF), the most common type of abnormal heart rhythm.

Fisherman’s platter

Back in 1983, more than 17,000 men revealed their dietary habits to researchers conducting the Physicians’ Health Study (PHS). More recently, a team from New York University Medical Center examined the PHS data to compare fish intake in 1983 and atrial fibrillation rates recorded 15 years later.

The result: Healthy subjects who ate more than five servings of fish each week raised their AF risk by more than 60 percent compared to subjects who ate fish only once a month.

These are the bare bones of a study that was presented at the Heart Rhythm Society’s Annual Scientific Session last month. In other words, the study hasn’t been published so we don’t have information about variables such as what types of fish were eaten and how the fish were prepared. And then there’s the detail that would certainly have a huge influence on the results: How did fish consumption vary between 1983 and 1998? It seems like after just a couple of years of eating six, or more fish meals per week, quite a few of those voracious fish eaters might wake up one morning and say, “Please! No more fish!”

Baked & broiled

A HealthDay News article about the NYU study offered an intriguing theory as to why heavy fish consumption might spike AF rates. Dr. Marie-Noelle Langan, chief of electrophysiology at New York’s Lenox Hill Hospital, told HealthDay that perhaps the subjects who ate mounds of fish were also very athletic. She notes that people who exercise by running excessively are prone to atrial fibrillation.

But I think the solution to the AF mystery may lie in this comment from a press release issued by the Heart Rhythm Society: “These findingsstand in contrast to those from a U.S. study conducted among an older population of men and women over the age of 65. In this older population, fish consumption was associated with reduced risks of developing AF.”

That “U.S. study” is almost certainly a Harvard Medical School study I told you about in the e-Alert “Kidney Punch” (10/28/04). The Harvard team examined 12 years of hospital discharge records, electrocardiograms and dietary data for more than 4,800 people over the age of 65.

Results showed that regular consumption of tuna or broiled or baked fish was clearly associated with a lower incidence of AF. 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.”

Now we’re getting somewhere! In fact, a fried fish sandwich might do considerable cardiovascular harm when multiplied by just three or four each week. In the e-Alert “David Beats Goliath Again” (5/15/03), I told you about a University of Washington study that demonstrated how those who regularly eat tuna and other baked or broiled fish (three or more times per week) may have a significantly lower risk of coronary heart disease (CHD) than those who eat the same fish infrequently. Those who regularly eat fried fish, however, could have a higher risk of both heart attack and death due to CHD.

The author of the NYU study – Dr. Anthony Aizer – told HealthDay News: “The message of this study is not to stop eating fish.”

Good call, Dr. Aizer. Perhaps a follow up study will tweak the message to read simply: Eat fish, but not fried fish.

Sources:
“Varying Effects of Fish Consumption on Atrial Fibrillation” Heart Rhythm Society press release, 5/18/06, eurekalert.org
“Fish Consumption Linked to Heart Abnormality” HealthDay News, 5/18/06, forbes.com
“Fish Intake and Risk of Incident Atrial Fibrillation” Circulation, Vol. 110, No. 4, 7/27/04, ncbi.nlm.nih.gov
“Cardiac benefits of fish consumption may depend on the type of fish meal consumed: the Cardiovascular Health Study.” Circulation: Journal of the American Heart Association, 2003 Mar 18;107(10);1372-7, circ.ahajournals.org