EWG’s Consumer Guide to Seafood

Find healthy seafood picks!

Thursday, September 18, 2014

EWG’s Consumer Guide to Seafood

Find healthy seafood picks!

EWG's Consumer Guide to Seafood

Which fish are richest in healthy omega-3 fatty acids, lowest in mercury contamination and sustainably produced?

Most government and standard public health references don’t tell you – so EWG will. EWG’s extensive analysis of the latest scientific research on seafood, omega-3s and mercury boils down to this easy guide.

 
Which fish are richest in healthy omega-3 fatty acids, lowest in mercury contamination and sustainably produced?

Most government and standard public health references don’t tell you – so EWG will. EWG’s extensive analysis of the latest scientific research on seafood, omega-3s and mercury boils down to this easy guide.

Use EWG’s Seafood Calculator at the right to get your custom seafood list – based on your age weight and more - or click here to see EWG’s general recommendations.

Get your custom seafood list

 

Legen Here
Show most popular fish
Show all fish
 
 
Category
Species
Weekly Mercury
Weekly Omega-3s
Sustainability
Conclusion
 
 
 
 

EWG's
Best Bets!

Very High Omega-3s, Low Mercury, Sustainable

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Category
Species
Weekly Mercury
Weekly Omega-3s
Sustainability
Conclusion
 
 
 

Good Choices

High Omega-3s, Low Mercury

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Category
Species
Weekly Mercury
Weekly Omega-3s
Sustainability
Conclusion
 
 
 

Low
Mercury

But Also Low Omega-3s

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Category
Species
Weekly Mercury
Weekly Omega-3s
Sustainability
Conclusion
 
 
 

Mercury
Risks Add Up

Pregnant Women And Children Should Limit Or Avoid

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Category
Species
Weekly Mercury
Weekly Omega-3s
Sustainability
Conclusion
 
 
 

Avoid

Mercury Levels Too High To Eat Regularly

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* Sustainability ratings for this species vary based on the location and method of harvest. Get details from the Monterey Bay Aquarium Seafood Watch program.
 
abbreviated version of EWG's Seafood Guide

 

 

Executive Summary

Many Americans would benefit from eating more seafood. Children born to mothers who eat fish and shellfish that are rich in omega-3 fatty acids and low in mercury during pregnancy have better cognition and behavior than children born to mothers who skip fish altogether, according to some scientific tests. People at average or high risk for heart disease can lower their blood cholesterol levels and reduce the risk of heart attacks and strokes when they make seafood a routine part of their diets.

EWG investigated existing data amassed by government and independent scientific institutions on seafood contamination and omega-3s. We found that both the mercury and the omega-3 fatty acid levels in fish and seafood vary widely.  We concluded that the federal government’s advice to Americans to eat more fish and avoid a few high-mercury species is seriously flawed and must be improved.

EWG's Good Seafood Guide fills the gaps of the federal government’s flawed seafood guidance.  Our aim is a user-friendly summary that helps consumers decide which seafood to eat, which to approach with caution and which to avoid.

 

Category

Species

Helpful Information

 

 

EWG's
Best Bets!

Very High Omega-3s, Low Mercury, Sustainable

  • Wild salmon
  • Sardines
  • Mussels
  • Rainbow trout
  • Atlantic mackerel

One or two four-ounce servings a week of these fish have little mercury and optimum levels of omega-3 fatty acids for pregnant or nursing women and people with heart disease.

 

Show Full Table

 

 

Good Choices

High Omega-3s, Low Mercury

  • Oysters
  • Anchovies
  • Pollock/Imitation crab
  • Herring

These species have favorable concentrations of omega-3 fats. One four-ounce serving provides at least 25 percent of the weekly recommended omega-3 consumption. A pregnant woman of average weight could eat three four-ounce servings per week without ingesting too much mercury. These species do not necessarily come from sustainable sources.

 

 

Low
Mercury

But Also Low Omega-3s

  • Shrimp
  • Catfish
  • Tilapia
  • Clams
  • Scallops
  • Pangasius (Basa, Swai, or Tra)

These varieties can be healthy sources of protein and other nutrients, but an adult would have to eat five to 20 four-ounce portions to meet the omega-3 recommendation for pregnant women and people with heart disease.

 

 

Mercury
Risks Add Up

Pregnant Women And Children Should Limit Or Avoid

  • Canned light and albacore tuna
  • Halibut
  • Lobster
  • Mahi mahi
  • Sea bass

These fish contain too much mercury to be part of the regular diet of pregnant women and children. How much you can safely eat depends on your age, weight and health status. Use EWG's Seafood Calculator to gauge how often you can eat them and to find healthier options.

 

 

Avoid

Mercury Levels Too High To Eat Regularly

  • Shark*
  • Swordfish*
  • Tilefish*
  • King mackerel*
  • Marlin**
  • Bluefin and bigeye tuna steaks or sushi**
  • Orange roughy**

High-mercury seafood should never be eaten by pregnant women and children, according to EWG's analysis and federal government warnings. Everyone else should eat these species infrequently or not at all.
 


 

*FDA/EPA advisories recommend that pregnant women and children never eat these species.

** EWG analysis concludes these species are high in mercury.

 

 

Because the amount of mercury you can safely consume depends on your pregnancy status and weight, EWG’s Seafood Calculator will give you personalized advice for more than 80 species of commercial fish and shellfish.

Consumers who read the proposed new seafood guidance by the federal Food and Drug Administration and Environmental Protection Agency will find references to omega-3 fatty acids buried in the agencies’ announcement, and omega-3s aren’t mentioned at all in a PDF summary linked to the announcement page.  The lack of emphasis on omega-3s is striking, because these beneficial fatty acids are one of the main reasons the government is encouraging people to eat more fish.

Consumers who scroll deep into the announcement page will see a table of commonly eaten fish and their associated omega-3 and mercury levels, but they will find it very difficult to determine from this table how much of various fish varieties they must eat per week to get the recommended amount of omega-3s.  Nor can they tell how much of each variety they can eat per week without consuming too much mercury.

As EWG’s January 2014 report cautioned, not everyone who follows federal government dietary guidelines and eats two or three fish meals per week will achieve the intended health benefits:  some people could consume too much mercury, and others, too few omega-3s (EWG 2014). Eight of the 10 seafood species most popular in the American diet are very low in omega-3s. Other popular choices, like canned albacore tuna, swordfish and some types of sushi, pose a significant mercury risk if pregnant women or children eat them frequently.

EWG believes that the federal government’s proposed seafood guidance is flawed for another reason:  it relies on a “safe” level established by the EPA in 2001.   Some prominent scientists now consider that level too high to protect the developing fetus and young children.  (Some evidence suggests that omega-3s in seafood could offset the deleterious effects of mercury to an extent.)

The EPA has launched a multi-year process to revise its assessment of mercury toxicity. EWG believes the agency should tighten its safe level to account for recent scientific studies that have found that children’s intellectual abilities suffer, even at trace exposure to mercury.

 

 

Why Eat Seafood? And How Much?

In June of this year the federal Food and Drug Administration and Environmental Protection Agency proposed new guidelines that encourage pregnant and nursing women to consume eight to 12 ounces of seafood of a variety of seafood per week, choosing from varieties lower in mercury (FDA 2014a). 

The FDA/EPA proposal represented a significant change from the agencies’ 2004 guidelines, which advised pregnant women, those who might become pregnant and nursing mothers to eat no more than 12 ounces of low-mercury seafood.  

This time around, the agencies set a floor as well as a ceiling on seafood consumption. They recommend that pregnant women, those who might become pregnant and nursing mothers boost their intake of fish dramatically, from 3.6 ounces per week, the current national average, to eight to 12 ounces weekly (FDA 2014a). They said young children should eat more fish, the amount dependent on their weight and age.  This advice echoed the Obama administration’s  Dietary Guidelines for Americans, published in January 2011, which said all adults should eat eight to 12 ounces of “a variety of seafood types” (USDA 2010).

The basis for this recommendation is research indicating that “good fats,” particularly polyunsaturated omega-3 fatty acids, offer extraordinary and unique health benefits.

The two most beneficial omega-3 fatty acids -- docosahexaenoic acid, known as DHA, and eicosapentaenoic acid, known as EPA -- have been shown to reduce inflammation and severity of heart and retinal diseases.  Children born to mothers who ate low-mercury seafood during pregnancy experienced better functioning brain and nervous systems.  They scored two to six points higher on intelligence tests than children whose mothers ate little fish during pregnancy (Oken 2005). A diet rich in omega-3s lowered blood triglycerols, reduced arrhythmias and decreased the risk of sudden death from heart disease (USDA 2010).

Fish and shellfish are low in fat, high in protein and good sources of iodine, vitamin D and selenium, often deficient in the Western diet. But decades of industrial activity, particularly emissions from coal-fired power plants, have released mercury and other pollutants into oceans and waterways.  Those contaminants end up in seafood.  While most commercial fish and shellfish contain some mercury, concentrations vary depending on the fishes’ ages, diet, region of harvest and other factors. Large predatory fish, including tuna, shark, marlin and swordfish, which eat smaller fish, accumulate considerable mercury over life spans that may run decades.

Omega-3 concentrations vary widely among species but are typically highest in species that dwell in cold water and have oily flesh.  Some fish species are high in mercury but low in omega-3s. Others have higher concentrations of omega-3s with very little mercury.

EWG strongly agrees with the administration’s Dietary Guidelines for Americans when it calls for Americans to eat more fruits and vegetables, high-fiber whole grains and seafood, and to eat less sugar, solid fat, refined grains and sodium. However we disagree with the blanket recommendation that all adults aim to eat 8 to 12 ounces of seafood per week. Many people are at low risk for heart disease, including vegetarians and other adults with an otherwise healthy diet. If all Americans followed the federal government’s advice, the amount of seafood consumed in the U.S. could triple, and global fisheries could suffer.

High-risk populations – pregnant women, children and people with heart disease—are likely to benefit from eating more seafood, provided they select varieties with the least mercury and optimum omega-3 content. To do so they need specific and detailed information about omega-3s and mercury content of common varieties.

EWG’s investigation of government and scientific data on seafood contamination and omega-3 content has found that seafood varied widely on both counts.  We conclude that the federal government’s approach, advising Americans to “eat more fish and to eat a variety of fish from choices that are lower in mercury,” is inadequate.  The reasons:  shoppers may not know that some commercial species likely to contain less mercury are also very low in omega-3 fatty acids.

In an analysis released earlier this year, EWG cautioned that not everyone who follows the government’s dietary guidelines and eats two or three meals per week would achieve the intended health benefits. This is a particular concern for pregnant women and young children who eat fish higher in mercury (EWG 2014). Our analysis found that:

The proposed FDA/EPA advisory urges pregnant women and children to avoid four species -- swordfish, tilefish, king mackerel and shark.  EWG goes further, recommending that people also limit their consumption of a larger number of moderate-mercury species.

Not all fish are equally nutritious. Twenty-one of the 35 common fish and shellfish we investigated would not provide an adequate amount of omega-3s when eaten twice weekly. This includes most fish and shellfish species often found in the American diet.
 
Dangerous substances besides mercury can build up in fish and shellfish. Among them are dioxin and other persistent pollutants.  While these pollutants are generally less harmful than mercury, their presence is a reminder that people who eat lots of fish or shellfish should pay attention to local seafood advisories and select only low-mercury species.

EWG recommends that people restrict their seafood consumption to two or three meals per week. Beyond that amount, the beneficial effects of omega-3s subside and the risks posed by contaminants add up.

How do you know you’re eating enough seafood and the right seafood?

 It all depends on who you are, your age, your pregnancy status and your health.

If you are considering getting pregnant, are pregnant or nursing

Federal nutrition guidelines recommend that you consume an average of 250 milligrams daily of DHA and EPA, the two omega-3 fatty acids found primarily in seafood (USDA 2010). The most critical period is the last 10 weeks of pregnancy.  

Not all seafood species are equal.  One to two servings of a high-omega-3 species like salmon, sardines or Pacific or Atlantic mackerel can meet the weekly recommendation for omega-3s. But a pregnant woman would need to eat five or more servings of tilapia, shrimp or catfish to get the optimum amount of omega-3s.

Because mercury from seafood can linger in your body, you should limit your mercury consumption before you conceive, or soon in pregnancy. Mercury can pass through breast milk.  It is wise to continue avoiding higher-mercury fish while breastfeeding.

Use EWG’s Wallet Guide and Seafood Calculator to find the healthiest options. 

If you are feeding children

Children benefit from eating seafood but should consume smaller portions. Always serve  low-mercury seafood.  Children should eat no more than one serving of canned light tuna per week.  Children should never eat canned albacore tuna, also known as white tuna.

If you have been diagnosed with heart disease

The Obama administration’s Dietary Guidelines for Americans report “moderate evidence” that consumption of two servings of seafood weekly can reduce the number of deaths from heart attacks and strokes. But eating more than two meals a week does not appear to offer additional benefits (USDA 2010).

On the other hand, eating high-mercury fish can erode some cardiac benefits of seafood (Burger 2013 citing Gullar 2002, Stern and Korn 2011). For this reason, people with heart disease should make an effort to limit their exposure to mercury.

If you are at low risk for heart disease and not pregnant

For most adults, seafood is beneficial but not essential.

Adults who eat fish frequently, particularly those who eat sushi, recreationally-caught fish or high-mercury fish, are at risk for mercury toxicity. Some studies of people who ate large quantities of fish or species high in mercury have reported neurological and other health problems.

If you eat fish or shellfish caught from local waterways

Many streams and rivers are contaminated with mercury and other pollutants from industrial pollution. Locally-caught fish can sometimes be more polluted than those purchased in stores. State and local governments have issued dozens of location-specific warnings and guidelines for taking fish and shellfish from polluted lakes and streams.  Check the U.S. Environmental Protection Agency’s searchable webpage for fish advisories by state, or check your state’s website for information about local waterways. When a local waterway is not the subject of a specific advisory, the FDA/EPA advisory recommends that adults eat no more than six ounces and children, one to three ounces, of any non-commercial fish and seafood per week (FDA 2014a).

If you love sushi and eat it frequently

People who eat sushi weekly, particularly high-mercury types such as tuna, are at risk for excessive mercury, according to a survey of more than 1,000 New Yorkers and New Jerseyans by scientists at Rutgers University (Burger 2013).  Tuna in sushi had three to 10 times more mercury than eel, crab, salmon and kelp rolls. Tuna served at upscale sushi restaurants and prepared as sashimi and nigiri had the highest mercury concentrations of all. Tuna in maki rolls sold at supermarkets and less expensive restaurants had lower mercury levels. The Rutgers study calculated that the 10 percent of respondents who ate the most sushi would ingest roughly triple the recommended daily intake for mercury (Burger 2013).

Many common sushi varieties are made from overharvested fish species. Check Monterey Bay Aquarium’s Sushi Guide for sustainability ratings.  

If you eat canned tuna

Americans eat more than 400 million pounds of canned imported tuna because it is affordable and can be stored for a long time. Albacore tuna, also called “white” tuna, contains significant amounts of omega-3s but also significant mercury contamination (USDA 2013, Karimi 2012, Consumer Reports 2011, Mercury Policy Project 2012). “Light” tuna is usually skipjack tuna but can also be yellowfin or tongol tuna. These varieties have lower mercury levels than albacore but fewer omega-3s (USDA 2013).

The June FDA/EPA advisory recommended that pregnant women limit their consumption of albacore tuna to six ounces weekly (FDA 2014a). EWG is more cautious:  we recommend that children, pregnant women and nursing mothers eat no more than two servings of albacore tuna per month, with the exact quantity depending on age and weight. [See EWG’s Seafood Calculator]
The June FDA/EPA advisory said canned light tuna was relatively lower in mercury (FDA 2014a). We disagree.  EWG recommends no more than one serving per week of light tuna for children and two servings for pregnant or nursing women.

If you don’t eat seafood

Omega-3s are important during pregnant and early childhood. But these fats are not as necessary for other adults, provided they eat an otherwise healthy diet. Pregnant women who don’t eat fish can find omega-3 fatty acids in fish oils, fortified foods and omega-3 supplements.

Oils containing the important omega-3 fatty acids DHA and EPA can be made from a variety of seafood species or extracted from algae. In general, dietary supplements are poorly regulated, so consumers cannot determine the supplements’ true omega-3 content.  Nor can they be sure mercury or other contaminants are not present. Few data are available on this problem.  Concentrations of mercury and other contaminants in supplements appear to be low and vary depending on the species of fish that serve as the basis for the particular supplement (Consumer Lab 2013, Covaci 2010, Foran 2003, Levine 2005).  Consumer Labs tests of fish oils sold in the U.S. found none with more than 0.01 parts per million mercury; in other words, a dose of a supplement contained less mercury than a single serving of most fish (Consumer Labs 2013).

Some milk, eggs and margarines are fortified with DHA.  Others foods, including canola oil, soybean oil, flax seeds, chia seeds and walnuts contain a third type of omega-3 fat known as alpha-lineoic acid or ALA, which the body can convert to DHA and EPA. However, people generally convert less than 10 percent of the ALA in their diet to EPA, which is then converted to DHA. This makes ALA consumption a less effective source of good fats, and less reliable option during pregnancy.

If you buy foods that claim to be fortified with omega-3s, check the product labels for DHA and ALA.  (No foods are supplemented with EPA.)  Nutritional guidelines suggest that women consume 250 milligrams of DHA and EPA daily during pregnancy.  Many foods contain far less.

The U.S. government’s Medline database rates fish oil supplements as “effective” for people with high triglycerides and “likely effective” for people with heart disease. But fish oil supplements are rated only as “possibly effective” treatments for many other health conditions, including arthritis, stroke, osteoporosis, age-related eye disease and attention deficit-hyperactivity disorder (MedlinePlus 2014).

There is no reliable scientific evidence that pregnant women and nursing mothers who take omega-3 supplements have infants who enjoy benefits in growth, neurodevelopment and vision comparable to women who ate seafood during pregnancy (Campoy 2012).

Fish oil supplements appear to be slightly less beneficial for cardiac patients than a seafood-rich diet (Rizos 2012), perhaps because seafood has important trace nutrients like iodine, vitamin D, vitamin B12 and selenium. As well, people who eat seafood are probably less inclined to eat unhealthy proteins like fatty or highly processed meats.  

EWG recommends that women who are pregnant and anyone at risk for cardiac disease consult their physicians if they do not eat seafood frequently to discuss other ways to add omega-3s to their diets.

 

Seafood Sustainability

Global fisheries are stressed by over-fishing and climate change.  Expanded American fish consumption would intensify strains on these resources.

Even as it recommended that adults consume eight to 12 ounces of seafood per week, the administration’s Dietary Guidelines for Americans recognized the threat to fisheries and called for “efficient and ecologically friendly strategies to allow for greater consumption of seafood [omega-3] fatty acids.”  It called for more research into ways to derive more DHA and EPA from plants (USDA 2010).

Aquaculture is often promoted as a way to increase fish and shellfish production and protect wild fisheries.  But aquaculture practices vary, as does their ecological impact. The Monterey Bay Aquarium’s Seafood Watch® program gives high marks for sustainability to farmed scallops, oysters, mussels, Arctic char, striped bass, catfish and rainbow trout.  But shrimp and salmon farming often damage surrounding ecosystems and sometimes employ antibiotics and chemical treatments to combat diseases compounded by over-crowding.

EWG believes Americans must consider the impact of their dietary choices on the ocean and freshwater ecosystems. One key step is to assess which segments of the population most benefit from seafood consumption and give them clear information about species and quantities that best provide health benefits. 

To that end, EWG has considered the seafood sustainability ratings of the Monterey Bay Aquarium’s Seafood Watch® program (Monterey Bay Aquarium 2014). This program, launched in 1999, provides science-based, peer-reviewed sustainability ratings for commercial fish species and updates its assessments on a rolling basis. Its green rating for “best choices” goes to sources of fish that are “well managed and caught or farmed in ways that cause little harm to habitats or other wildlife.” The “yellow” rating for “good alternatives” goes to species with “some concerns” for sustainability. “Red” ratings for fish to avoid mean fish with strong sustainability concerns.

Consumers seeking sustainable choices face a challenge:  sustainability ratings for a single species can range from green to red.  Many grocery stores show ecological ratings for specific varieties. Restaurants participating in sustainability programs like Fish Choice verify that all seafood menu items are from sustainably-managed fisheries.

EWG’s “best bets” are species likely to contain little mercury and other contaminants and that come from sources rated as sustainable by Seafood Watch®.  Check out seafood ratings and download the Seafood Watch® app.

 

Mercury Toxicity

Methyl mercury is toxic to the human brain, kidney, liver, heart and nervous system. Research has shown that people who eat a lot of high-mercury fish frequently can experience nervous system damage and can suffer from a variety of ailments, including sleep disturbance, headache, fatigue, difficulty with memory and concentration, poor coordination and neuropathy (Hightower 2003, Silbernagel 2011, Groth 2011). Symptoms of mercury toxicity generally subside slowly once people stop eating fish high in mercury (Hightower 2003).

Mercury is much more dangerous to the developing fetus. Mercury exposure during pregnancy can cause lasting deficits in the development of a child’s brain and nervous system.  Studies of children exposed to high levels of mercury in the womb indicate that they score lower than other children on intelligence tests and perform poorly on tests of memory, attention and hyperactivity (Debes 2006, Grandjean 2012, Sagiv 2012). Mercury exposure during infancy and early childhood is also believed to be harmful.

In 2001 the EPA concluded that a pregnant woman could consume 0.1 micrograms of mercury per kilogram of bodyweight daily without ill effects to her fetus and that this amount of mercury would also be safe for children and adults (EPA 2001).

Since then, however, several studies have found measurable damage to infants’ brain development in mothers exposed to lower levels of mercury. Many of these studies found that omega-3s in seafood could offset the deleterious effects of mercury to some degree. A study of 341 Boston-area women found that the 10 percent of women with the highest blood-mercury measurements gave birth to children with poorer brain development, measured at 18 months and three years (Oken 2005, 2008).  Those mothers who ate three or more seafood meals weekly gave birth to children with better brain development.  The authors concluded that “recommendations for fish consumption during pregnancy should take into account the nutritional benefits of fish as well as the potential harms from mercury exposure" (Oken 2008).

Several scientists and advocates specializing in mercury damage have concluded that the EPA’s safe level is too lax to protect the developing fetus (Bellinger 2014). Some have recommended that the EPA lower its mercury exposure level by 50 to 75 percent (Grandjean 2012, Zero Mercury 2012). 

The EPA has launched a multi-year process to revise its assessment of mercury toxicity. EWG believes the agency should lower its safe level to account for the recent scientific studies that have found that children’s intellectual abilities suffer even at trace exposure to  mercury.  The agency should accelerate its efforts to encourage people who eat fish frequently to seek out varieties lower in mercury.

In the meantime, since government and independent scientists have not reached a consensus on a safe level of mercury exposure, EWG’s Seafood Calculator and Wallet Guide aim to steer people toward seafood with the best safety profiles, something we can do with confidence.  

EWG recommends that pregnant women and children consume no more than 75 percent of EPA’s safety level.  By doing so, they are likely to build a extra margin of safety from lifelong damage mercury can inflict on the developing brain.

 

Frequently Asked Questions

 

  1. Why is mercury in fish?
  2. Why should we eat more fish? Aren’t global fisheries at risk?
  3. Should I be concerned about other pollutants in seafood?
  4. How much seafood should I eat?
  5. I am vegetarian, what should I do to get omega-3 fats?
  6. Should I take an omega-3 (DHA) supplement?
  7. How does EWG’s seafood advice differ from the 2014 advisory issued by the FDA and EPA?

Why is mercury in fish?

Industrial mining and coal-fired power plants are the major sources of mercury in the environment. When mercury is emitted into the air, it condenses and falls into waterways and oceans, where bacteria and zooplankton transform it into methyl mercury, an organic compound that is more toxic than elemental mercury and inorganic mercury compounds.

Methyl mercury pollution concentrates in the marine food chain.  Mercury concentrations are highest in predatory fish that eat smaller fish. In 2013 the U.S. and 100 other nations signed the Minamata Convention, a global treaty committing signers to reducing mercury emissions. The treaty is a good start, but as ocean temperatures rise because of global warming, mercury accumulation is projected to intensify due to increased metabolic activity in the marine creatures in the lowest tier of the ocean food chain. This increase in mercury could lead to greater concentrations in larger fish and increased risk for seafood consumers.

Why should we eat more fish? Aren’t global fisheries at risk?

Over the past decade the scientific evidence on the health benefits of fish consumption has become more definitive. Federal nutrition guidelines now recommend that all adults and children aim to eat two or three seafood meals per week. If Americans adopted this advice the massive increase in seafood consumption would strain global fisheries. EWG encourages consumers to optimize the benefits of seafood by picking healthy, sustainably produced seafood. The Monterey Bay Aquarium  Seafood Watch® website offers extensive details about ecological sustainability of commercial fish and shellfish stocks.

What about other pollutants in seafood?

Decades of industrial activities have polluted fish and shellfish with a variety of toxic chemicals. Fat-accumulating organic molecules like dioxin and PCBs can be found in fatty fish, which are in many cases those with higher concentrations of omega-3 fats. In general the benefits of eating fatty, low-mercury seafood from commercial fisheries outweigh other the harms from other persistent contaminants. However if you eat more than three meals per week, or get species harvested from highly polluted areas the balance could shift. Frequent fish eaters should search EPA’s database of government warning for local waterbodies. In general it is healthiest to eat a variety of species to minimize the risks from elevated levels of pollutants in any particular species.

How much seafood should I eat?

That depends primarily on your health status. If you are pregnant, nursing or have heart disease, you should eat fish and shellfish with some regularity.

EWG recommends that people who enjoy eating seafood aim for one or two meals of sustainable, low-mercury seafood each week. Pregnant women, children and people with heart disease should include species high in omega-3 fatty acids. More than three meals per week may not be beneficial and increases your exposure to other contaminants in seafood. EWG’s EWG’s Good Seafood Guide gives specific recommendations for women who are pregnant or considering pregnancy, parents feeding young children, people with heart disease, sushi or tuna lovers, and people who eat non-commercial fish and shellfish.

EWG’s Seafood Calculator will help you pick the best seafood and give advice tailored to your age, weight and health status.

I am a vegetarian, what should I do to get omega-3 fats?

Vegetarians may miss out on some of the health benefits of omega-3 fatty acids, because they are found primarily in fish and shellfish. If you are pregnant, nursing or considering pregnancy, you should consult with your doctor about the best way to add extra omega-3 your diet. Some nutritional supplements market DHA and EPA extracted from seaweed, and some omega-3 fortified eggs and margarines derive omega-3s from vegetarian sources. If you buy foods that claim to be fortified with omega-3s, check the DHA or ALA content.  (No foods are supplemented with EPA.)  Keep in mind that nutritional guidelines suggest that women consume an average of 250 milligrams of DHA and EPA daily during pregnancy.  Many foods contain far less.

Should I take an omega-3 (DHA) supplement?

There are a variety of omega-3 nutritional supplements that contain DHA and EPA. Most are derived from fish oil. In general, dietary supplements are poorly regulated, so consumers do not have independent verification of the omega-3 content or contaminants in fish oil supplements.  Consumer Labs tests of fish oils sold in the U.S. found none with more than 0.01 parts per million mercury; meaning fish oils contained notably less mercury than a single serving of fish (Consumer Lab. 2013).

The National Center for Complementary and Integrative Health, a branch of NIH reports that eating fish is generally more beneficial than omega-3 supplements, particularly for cardiac health. This may be due to the fact that in addition to omega-3s, seafood has important trace nutrients like iodine, vitamin D, vitamin B12 and selenium. The Office of Dietary Supplements gives a more detailed review of the evidence about beneficial omega-3 fats.

While many studies find a benefit of consuming fish during pregnancy there is less evidence that omega-3 supplements provide a similar benefit.(Campoy 2012) One recent meta-analysis found existing evidence did not “support or refute that omega-3 supplementation improves cognitive or visual development.”(Gould 2013) Another concluded the some evidence of lower rates of some allergies in children in the first three years of life, but researchers concluded the overall evidence was “limited” on the ability of omega-3 supplements to lessen risks of allergic diseases.(Gunaratne 2015) Yet at least one expert in seafood and pregnancy recommend omega-3 supplements as a low risk and possibly beneficial supplement during pregnancy.(Oken 2012)

Fish liver oils, such as cod liver oil, are not the same as fish oil supplements. Fish liver oils contain high doses of vitamins A and D in addition to omega-3 fatty acids. Both of these vitamins can be toxic in large doses, and excessive vitamin A is particularly harmful during pregnancy and childhood.

EWG recommends that women who are pregnant and anyone at risk for cardiac disease consult their physicians if they do not eat seafood frequently to discuss other ways to add omega-3s to their diets.

How does EWG’s seafood advice differ from the 2014 advisory issued by the FDA and EPA?

EWG’s recommendations are stricter, more comprehensive and more user-friendly than those of the federal agencies.

Our calculator and wallet card aim to steer consumers toward the species that provide the highest amounts of omega-3 fatty acids and least mercury. In contrast the FDA and EPA recommend that pregnant women eat seafood frequently but name only four highest mercury species to avoid. EWG recommends limiting additional high-mercury species. The EWG Seafood Calculator estimates portion size and frequency based on a child or adult’s weight and recommends that pregnant women and children ingest 25 percent less mercury than the current EPA guideline.

The FDA and EPA issued their first Joint Advisory on Seafood in 2004, before the protective role of omega-3 fatty acids in pregnancy was clearly understood.  Earlier this year the FDA and EPA proposed to update their joint advisory to recommend that pregnant women eat a minimum of 8 to 12 ounces of fish and seafood per week and to “choose fish lower in mercury” (FDA 2014a).  But the draft guidelines do not provide the details that consumers need to select the healthiest species. EWG has urged the agency to provide more specific and protective guidance for consumers.

For example, consumers who read the proposed new seafood guidance by the federal Food and Drug Administration and Environmental Protection Agency will find that the first mention of omega-3 fatty acids is well down on the first page of the agencies’ announcement and does not appear at all on a PDF summary linked to that page,  even though omega-3s are a primary reason the government is encouraging people to eat more fish. Consumers who scroll down the announcement page will find a table of commonly eaten fish and their associated omega-3 and mercury levels, but it is very difficult to determine from this table how much of these fish people must eat per week to get the recommended amount of omega-3s and how much they can eat per week without getting too much mercury.

As EWG’s January 2014 report cautioned, not everyone who followed federal government dietary guidelines and eats two or three fish meals per week will achieve the intended health benefits because some people could consume too much mercury, and others, too few omega-3s (EWG 2014). Eight of the 10 most popular seafood species are very low in omega-3s. Other popular choices, like canned albacore tuna, swordfish and some types of sushi, pose a risk of too much mercury if pregnant women or children eat them frequently.

EWG has repeatedly urged the federal government to improve its guidelines for mercury in seafood and to get contaminated species off store shelves. We have stressed that it must provide consumers with clearer and more detailed advice about mercury in seafood and must highlight clearly beneficial choices, or consumers may consume too much mercury and/or too few omega-3s (EWG 2014). Until the government heeds our advice, EWG’s Seafood Calculator is the only online consumer guide that gives health-based seafood recommendations that incorporate both beneficial fatty acids and mercury concerns and that tailor portion size and frequency recommendations based on an individual’s bodyweight and health status.

 

Methodology: 

Federal nutrition guidelines advise Americans to eat more fish and shellfish but do not make it easy for consumers to figure out which kinds of low-mercury fish provide lots of omega-3s. EWG believes that the federal government’s proposed seafood guidance is flawed because it relies on a safe dose level established by the EPA in 2001 and now considered outdated and too high by many scientists.

EWG’s Seafood Calculator and Wallet Guide consider both the beneficial omega-3 fatty acid content and mercury levels in commercial species so that consumers can choose fish and shellfish better for their health.

Wallet Guide and Calculator Seafood Ratings

EWG classified seafood into five categories using the parameters described in the table below.

EWG Seafood Rating Category

Omega-3 content in 4-ounce serving*

Mercury content**

Sustainability***

EWG Best Bets
At least 50% of Dietary Guidelines weekly recommendation
Eat up to 12 ounces weekly – Mercury = Less than or equal to 0.1 ppm
Best sustainability rating

Good Choices
At least 25% of Dietary Guidelines weekly recommendation
Eat up to 12 ounces weekly –Mercury = Less than or equal to 0.1 ppm
Any

Low Mercury, But Low Omega-3s
Less than 25% of Dietary Guidelines weekly recommendation
Eat up to 12 ounces weekly - Mercury = Less than or equal to 0.1 ppm
Any

Mercury Risks Add Up
Any
Can eat 4 to 8 ounces weekly – Mercury = 0.1 to 0.3 ppm
Any

Avoid
Any
Eat less than 4 ounces weekly – Mercury = greater than 0.3 ppm
Any

* The Dietary Guidelines for Americans recommend that pregnant women and people with heart disease consume an average of 250 mg of DHA and EPA daily, or 1,750 mg a week (USDA 2010).
**  EWG’s recommended weekly limit for mercury ensures that a woman weighing 166 pounds,  the average weight for American women, ingests no more than 75 percent of EPA’s outdated safe level for mercury (EPA 2001) when she eats 12 ounces of seafood per week, based on the average mercury concentration in each species (Karimi 2012).
*** Sustainability ratings derived by Monterey Bay Aquarium Seafood Watch™ program.

Mercury assumptions

To minimize the risk of exposing the developing fetus to too much mercury, EWG recommends that pregnant women and young children aim to keep their mercury intake well below the EPA guideline. EWG’s Seafood Calculator recommends that pregnant women and children not exceed 75 percent of EPA’s outdated mercury safe level (technically called the “reference dose”). For all other adults we base our calculations on EPA’s reference dose. Our analysis bases calculations on a woman weighing 166 pounds, the average for American women. EWG’s Seafood Calculator allows people to determine the appropriate serving size and frequency based on their bodyweight. Lighter adults and children should further limit their mercury intake by eating smaller portions or eating that species less frequently.

Portion size assumptions

EWG’s Seafood Calculator is based on a four-ounce portion, as specified in the Dietary Guidelines for Americans. Four ounces is roughly the size and weight of a deck of cards or equivalent to one tin of sardines or anchovies and four to six pieces of sashimi. Restaurants generally serve larger portions than these. Young children should eat smaller portions than adults. The FDA and the Dietary Guidelines for Americans do not specify a standard serving size for children. EWG’s calculator bases recommendations on the assumption that a child size portion is one ounce for every 20 pounds of weight.

Data sources for mercury concentrations in commercial fish and seafood

While mercury concentrations can vary widely within a particular species, it is possible to make some generalizations based on the average mercury content recorded in scientific monitoring studies. The FDA bases its assessment of mercury risks from seafood on incomplete data. Its recent benefit-risk assessment for children employs a study performed in 1978 and about 5,000 individual fish samples collected between 1990 and 2010 (FDA 2014b).  FDA’s monitoring program has been criticized for sampling too few fish to account fully for variation in mercury concentrations (Karimi 2012).

To evaluate the amount of mercury in commercial fish and shellfish species, we used a large database of 300 studies, plus FDA’s monitoring data, assembled by Roxanne Karimi and Nicolas Fisher of Stony Brook University and Timothy Fitzgerald of the Environmental Defense Fund (Karimi 2012).  These researchers found that in many cases mercury concentrations in their database exceeded measurements taken by FDA monitoring. They suggested that the FDA broaden its investigation of mercury in seafood and consider other data sources when determining safe consumption levels for seafood. Mercury estimates in the Stony Brook Seafood Hg Database were more than 20 percent higher than FDA estimates for 27 of 58 species examined, with notable differences in moderate- or higher-mercury species, including marlin, king mackerel, weakfish/seatrout, and freshwater trout. The researchers found relatively few monitoring studies from Asia and the Pacific Ocean even though substantial quantities of fish and shellfish from these regions reach the U.S. We use a weighted average of mercury concentrations for fish and shellfish species and sub-species using the name classifications from the Stony Brook Hg Database.

The Stony Brook Seafood Hg Database includes studies published through December 2010.  To provide additional data for commercially important species, we added information from four more studies -- three studies of canned tuna (Consumer Reports 2011, Mercury Policy Project 2012, Gerstenberg 2009), and one study of mercury in thousands of samples of Great Lakes walleye – a regionally important fish for people residing in the inland U.S. (Monson 2011).

Data sources for omega-3 levels in seafood

EWG’s Seafood Calculator uses data reported by the USDA Nutritional Database last year (data release SR-26) to evaluate the concentrations of DHA and EPA in seafood (USDA 2013). We evaluated measurements from both raw and cooked fish samples.

Omega-3 data are less robust than mercury measurements. The USDA database contains far fewer measurements from each species and reports substantial variation among samples. Even so, it generally aligns with a global database of omega-3 fatty acids developed by the World Health Organization and the Food and Agricultural Organization in their 2010 report on seafood safety (WHO-FAO 2010). The USDA data are more relevant to the species sold commercially in the U.S. For that reason, EWG used the USDA dataset as the basis for our consumer recommendations. When both raw and cooked fish were analyzed we included data from both types. Omega-3 concentrations for popular species were in the ranges reported in independent monitoring efforts (Shim 2004). Scientific institutions should develop better data on omega-3 levels in common seafood species.
EWG’s Seafood Calculator bases its recommendations for omega-3 consumption on the recommendation in the Dietary Guidelines for Americans that pregnant women and people with heart disease consume an average of 250 mg of DHA+EPA daily or 1,750 mg per week (USDA 2010).

Challenges of providing consumer guidelines for seafood

Consumers’ efforts to purchase healthy seafood are complicated by several factors. Commercial and recreational fish are sold under many common or “market names”. Consumers seeking Coho salmon might find it labeled “silver salmon” at a fish counter. In other cases a fish labeled “ahi tuna” at a store or restaurant could actually be bigeye or yellowfin tuna, species with different mercury concentrations.

Fish are commonly mislabeled at the point of sale (GAO 2009). Advocacy group Oceana analyzed DNA from fish samples collected between 2010 and 2012 and found that many samples were mislabeled, most commonly mis-marketed were snapper and tuna. Only 7 of 120 samples of fish sold as “red snapper” were actually correctly labeled, the remaining 113 samples were another type of fish (Oceana 2013). In some cases consumers unknowingly purchase higher mercury varieties, including king mackerel sold as grouper and escolar labeled white tuna.

Our analysis bases portion size recommendations on the average mercury value from existing monitoring studies. However mercury concentrations vary widely among individual fish samples and among sub-species of the same fish. In order to provide straightforward advice we group together sub-species of fish like perch, seatrout, seabass and shark. However consumers who eat a particular sub-species of these fish may be at greater risk if it has higher mercury concentrations.

People who catch or eat non-commercial species may eat more mercury or other contaminants than reflected in our analysis of commercial species. The EPA has a clearinghouse of state and local fish and shellfish advisories for mercury and other contaminants in seafood (EPA 2014). The FDA/EPA draft advisory recommends that consumers limit non-commercial species to no more than six ounces per week. Children should eat only one to three ounces of any non-commercial fish and seafood per week.

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