Tuna Warning Complicates Healthy Living Quest

Auburn, Dec. 16, 2003 --- Healthier living may have just gotten harder.  

The Food and Drug Administration and the Environmental Protection Agency are drafting a 
warning that advises pregnant women and children to limit their intake of tuna and other fish and 
shellfish to 12 ounces a week, roughly two or three servings.  They also advise all Americans to 
mix the types of fish they eat and to avoid consuming too much other saltwater fish, such as 
shark, swordfish and mackerel.  All of these species may contain high levels of mercury, a toxic 
substance linked with cardiovascular disease and neurological damage. 

The new warning brings added frustration to the millions of Americans who have made an effort 
in recent years to eat more fish.  Studies have shown that omega-3 fatty acids, which abound in 
ocean-caught sporting fish, may be a powerful safeguard against heart disease and neurological 
damage that frequently accompany aging.

Still, the question remains: If ocean-caught fish should be eaten only in moderate amounts, where 
do we look for these omega-3’s?  Farm-raised fish, such as salmon and catfish, free of the 
contamination associated with ocean-caught fish, seem like obvious alternatives.  But there’s one 
hitch:  While perfectly safe excellent low-fat sources of protein, neither of these fish necessarily 
compare favorably with ocean-caught fish --- at least from the standpoint of omega-3 fatty acids.

“With catfish, for example, most omega-3 fatty acids are deposited in the abdomen or below the 
skin.  They don’t lay down a lot of it in their muscle tissue,” said Dr. Russell Wright, an Alabama 
Cooperative Extension System fisheries specialist and Auburn University associate professor of 
fisheries and allied aquacultures.  “So when we clean the fish, we tend to do away with a lot of 
the omega- fatty acids, though there will still be some in the tissue.”

Also, the types of Omega- fatty acids commonly found in catfish don’t compare favorably with 
those in saltwater fish.  Tuna especially abounds in the long-chained omega-3, such as DHA, 
commonly considered the best safeguard against cardiovascular disease and neurological 
damage.  Catfish, on the other hand, pales in comparison, said Dr. Allen Davis, an Auburn 
University assistant professor of fisheries, who specializes in aquatic nutrition.   The highly 
unsaturated omega-3 fatty acids associated with heart and brain health can be added through 
feeding, but only to a limited degree, he said.

Farm-raised salmon can be an exceptionally good source of omega-3 fatty acids but only as long 
as they receive adequate amounts of omega-3’s on the farm.

 “It all depends on what they were fed on the farm,” said Dr. Robert Keith, and Extension 
nutritionist and Auburn University professor of nutrition and food science.  “If they eat plants or 
commercial feeds that are high in omega-3’s, you can count on their being good sources of 
omega-3 fatty acids.  But it all boils down to what they’re eating.”

Farm-raised salmon is now the most common source of salmon in the United States.

“The vast majority of fresh filet salmon commonly sold in seafood and supermarkets is farm 
raised,” Wright said.  “In fact, you really have to go out of the way to find ocean-caught salmon.”

Canned salmon, on the other hand, is almost entirely derived from wild-caught salmon, he said.

Keith said supplements are an alternative for consumers unwilling or unable to eat fish, but they 
lack the other benefits associated with fish.

The incentive for salmon farmers to supplement feeds with omega-3 just got stronger.  Convinced 
that omega-3 fatty acids are a powerful safeguard against heart disease, the American Heart 
Association recommended in November that Americans with heart disease consume at least one 
gram of omega-3 fatty acids daily to reduce their risk of heart attacks.  This marks the first time 
the AHA has recommended a food supplement as a method for sustaining heart health.
[Sources: Dr. Russell Wright, Extension Fisheries Specialist and Auburn University 
Associate Professor of Aquaculture and Allied Aquacultures, (334) 844-9311; Dr. Robert 
Keith, Alabama Cooperative Extension System Nutritionist and Auburn University 
Professor of Nutrition and Food Science, (334) 844-3273; Writer: Jim Langcuster, 
Extension Communications Specialist, News and Public Affairs, (334) 844-5686.]