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Best and Worst Fish Choices

A Guide for a Healthy Body & Planet

-- By Becky Hand, Licensed and Registered Dietitian

Word is spreading that fish is good for your health, but like many matters of health and nutrition, there’s nothing simple about simply eating fish. Even though many varieties can be good for your health, contaminants such as mercury and polychlorinated biphenyl (PCB), found in many types of fish, may be detrimental to your health.

But it gets even more complicated. Beyond choosing fish based on healthfulness (considering things like abundance of healthy omega-3 fatty acids and low concentrations of mercury and contaminants), consuming fish also has an environmental impact. Many environmental advocates have reported that the mismanagement of many large-scale fishing operations has resulted in overfishing (and the plummeting of some wild fish populations). Fish farming, one alternative to wild fish, may help protect these populations, but other groups claim that fish farming has led to other problems, like the overuse of antibiotics to control disease.

Trying to keep track of which types of fish are healthy and safe—not only for you, but also for the environment—can be daunting, to say the least. And here’s why: Making the right choice when it comes to fish means looking for fish that have the highest nutritional content, lowest levels of contaminants, and, for those concerned with the environment, the lightest impact on the planet. Let's explore how to make the best choices to meet all of these tricky requirements.

Nutrition and Omega-3s
Nutrients found in foods are usually straightforward.  When choosing fish, people generally want to know which types are highest in omega-3 fatty acids. Concerning omega-3s alone, the following chart ranks the omega-3s in fish from highest content to lowest.
 

Species
3 oz edible portion
Grams
Omega-3
Mackerel, Atlantic 2.6
Chub 2.6
Herring 2.5
King Mackerel 2.2
Chub Mackerel 2.2
Trout, lean lake 2.1
Spiny Dogfish 2.0
Trout, lake 2.0
Salmon, Atlantic, farmed 1.9
Herring, pacific 1.8
Whitefish 1.8
Herring, Atlantic 1.7
Bluefin Tuna 1.6
Chinook Salmon 1.5
Sablefish 1.5
Albacore Tuna 1.5
Whitefish, lake 1.5
Sturgeon, Atlantic 1.5
Canned Sardines 1.4
Pink Salmon 1.0
Smelt 1.0
Striped Bass 0.8
Pollock 0.5
Catfish 0.5
Halibut, Pacific 0.5
Catfish or Cod 0.3
Flounder or Perch 0.2
Snapper or Grouper 0.2
Sole 0.1

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Contaminants
When you start to consider contamination from mercury and PCBs (Polychlorinated biphenyl, or industrial chemicals), picking the best fish gets a little more confusing. Organizations such as the Food and Drug Administration (FDA), Institute of Medicine (IOM), Food and Agriculture Organization of the United Nations (FAO), and the World Health Organization (WHO) have tried to weigh the contamination risk of eating fish against the nutritional benefits it provides.  The EPA and FDA have established guidelines for pregnant women, women trying to conceive, nursing mothers and young children. For other adults, the general advice is to basically ''eat fish.''  Based on research, these groups feel that the health benefits of eating fish far outweigh any risk from contaminants.  While it may be possible that a fish could be so high in contaminants and low in omega-3 fatty acids that it could do you more harm than good, no such fish has been found to date that fits this description.  The advice from these organizations is to eat two or more servings of fish weekly from a variety of species, therefore reaping the nutritional benefits and lessening the risk of over-exposure to the same contaminant in the same species repeatedly.   

On the other end of the spectrum is the Environmental Defense Fund (EDF).  This group has a published guide that lists 20 species of fish from which adults should consume no more than once serving per month.  When formulating their list, the EDF only considers risk—how much contaminant is present—not whether the listed fish may have any health benefit that could outweigh the contamination risk.  Both the EPA and FDA are concerned about the overstating of risk by the EDF, when using a risk-only method to compare fish. They have therefore set up an advisory for fish consumption for all US states based on available species. 
 
Experts on both sides of the discussion agree that, in theory, it is possible to get excessive mercury contamination by eating a large quantity of high-mercury fish---but they don’t agree on how much is too much.  However, the amount of fish that would need to be consumed is far more than the 3 oz. of fish per week that Americans are currently eating, on average.    
 
For people concerned with mercury contents of fish, refer to the guide below.  Mercury concentration is listed as Parts Per Million (PPM):
  • The fish with the highest levels of mercury include:  tilefish (1.45), swordfish (0.995), shark (0.979), and mackerel king (0.730).
     
  • The fish and shellfish with the lowest levels of mercury include:  anchovies, catfish, clam, cod, crab, haddock, herring, jacksmelt, spiny lobster, mackerel, mullet, oyster, perch, pollock, salmon (canned, fresh and frozen), sardine, scallop, shad, shrimp, tilapia, trout, tuna (canned, light), whitefish and whiting.  These varieties of fish have a mercury range of (0.008 - 0.128 PPM).
     
  • Fish and shellfish that fall in the middle area include:

Species Mercury PPM
Orange Roughy 0.571
Spanish Mackerel 0.454
Grouper 0.448
Bluefish 0.368
Sablefish 0.361
Frozen/Fresh Albacore Tuna 0.358
Frozen/Fresh Yellowfin Tuna 0.354
Canned Albacore Tuna 0.350
Halibut 0.241
Snapper 0.166
Bass 0.152
Perch 0.150
Tilefish, Atlantic 0.144
Fresh/Frozen Skipjack Tuna 0.144
Carp 0.137

Environmental Concerns
Finally, there is the concern of depleting the waters of fish and using ecologically damaging methods of fishing and fish farming.   Sustainable fishing practices are critical to preventing the extinction of fish species.  Advocacy groups, grocery stores, and consumers are trying to help reverse trends of overfishing so that the industry as a whole can move toward greater sustainability.  Environmental concerns are different from region to region in the United States and throughout the world.  Concerns can also change seasonally as well.  For the most up-to-date information on selecting fish with the least environmental burden, please check out the sustainability of your fish choices using this listing by the Monterey Bay Aquarium
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General Fish Guidelines for Health
Considering all of the nutritional, contamination and environmental concerns that surround fish, it's easy to see why adding more fish to your plate can be confusing. Based on the research and information currently available on all of these issues, here are my nutritional recommendations regarding fish:
  • Pregnant women, women trying to conceive and families with young children should follow the EPA/FDA fish consumption guidelines.
     
  • Other adults should simply eat fish. The data shows that the health benefits of eating several 3- to 4-oz. (cooked) servings weekly outweighs the risks of ingesting contaminants in fish.
     
  • Eat a variety of fish species and be sure to include smaller-sized fish in your selections, for they contain a lesser amount of contaminants.  Examples include:  catfish, cod, haddock, Atlantic mackerel, ocean perch, pollock, salmon, canned light tuna, and whitefish. 
     
  • If you are mostly vegetarian or a pescetarian (a person who relies on fish as your primary protein source), most of the fish you eat should have a ''lower level of mercury'' as indicated in this chart from the FDA.
     
  • If you are an angler, check with the local authorities for contaminant levels where you fish.  Limit your consumption if those levels are high.
     
  • When purchasing fish, check with your grocery store or supplier to assure that they are selling only sustainable fish and seafood products.  
 
Within the field of food, nutrition, and health it is easy for consumers to get mixed messages that result in confusion and frustration.  Sensationalism sells and the fear of harm often overshadows the science of health benefits. However, by following the steps above, you can easily develop your own individualized plan for fish consumption that will allow you to reap the health benefits while decreasing your risk of ingesting contaminants.
 

Sources
 
Environmental Defense Fund. ''Complete List of Seafood Eco-Ratings,'' accessed April 2012. http://apps.edf.org.
 
Monterey Bay Aquarium Seafood Watch. ''Seafood Recommendations,'' accessed April 2012. http://www.montereybayaquarium.org.
 
United States Environmental Protection Agency. ''What You Need to Know about Mercury in Fish and Shellfish,'' accessed April 2012. http://water.epa.gov.
 
United States Environmental Protection Agency. ''Advisories Where You Live,'' accessed April 2012. http://water.epa.gov.
 
United States Food and Drug Administration. ''Mercury Levels in Commercial Fish and Shellfish (1990-2010),'' accessed April 2012. http://www.fda.gov.
 

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