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Fish: What Should You Do?

With so many news releases telling us which types of fish are safe to eat and which are not, it can be confusing to sort out how to safely incorporate fish into your diet.

Benefits

Let's break down the benefits and dangers of consuming fish. Most of us know that fish are an excellent source of lean protein and are low in saturated fat. The "fatty fish" (or cold-water), namely herring, lake trout, salmon, and sardines, are an excellent source of heart-healthy omega-3 fats.

Risks

However, recent government studies have revealed that many of the fish we consume may contain excessive levels of mercury, PCBs (polychlorinated biphenyls), dioxin, pesticides and PBDE (polybrominated diphenyl ethers) flame retardants. Most studies have focused on mercury and PCB levels in fish, since data on other contaminants is incomplete (IATP).

Mercury and Health Risk

One of the most toxic forms of mercury is methylmercury, an organic compound that can build up in animal tissues. Mercury enters our waterways as it falls out from airborne pollution from the burning of fossil fuels. It can also contaminate the soil and wash into water systems. Once mercury enters a water system, it is converted to its highly toxic form, methylmercury, by bacteria present in the water.

The fish found in these waters can subsequently become contaminated in two ways: through absorption of the contaminates in the water and/or through consumption of contaminated prey. According to the National Institutes of Health (NIH), excessive exposure to mercury can result in neurological and kidney damage, and can lead to death.

Risk is low

While the FDA has reported that most fish contains traces of mercury, they emphasize that the health risk is low for most healthy adults. Those who should monitor their fish intake include pregnant women, women who may become pregnant, nursing women, and young children. It is important for women who are planning to become pregnant to monitor their fish consumption, because methylmercury can remain in the body for up to a year before it is eliminated from the body.

Consumption of tuna should also be restricted to not greater than 6 ounces per week and total weekly fish consumption should be less than 12 ounces during the pregnancy.

FDA Advisory - as of March 2004

For those concerned about mercury contamination, the FDA recommends consuming up to 12 ounces (2 average meals) of fish per week. The FDA has also compiled a list of fish and shellfish that are low in mercury so as to guide your choices.

Fish low in mercury - safe to eat up to 12 ounces per week:

• shrimp
• canned light tuna
• salmon
• pollock
• catfish
• Albacore tuna - higher in mercury - safe to eat 6 oz per week

Fish high in mercury (pregnant women should avoid these fish):

•  swordfish

•  shark

•  king mackerel

•  tilefish

PCBs and Health Risk

PCBs, a chemical compound previously used in electronic equipment, printing inks, paints, and pesticides, was banned in 1979 after it was discovered that they were carcinogenic. Despite the ban, PCBs still remain in the air, soil, and water, since they are a very stable compound and do not easily break down. As with mercury, fish absorb PCBs through the water and by consuming contaminated organisms. PCBs tend to concentrate in the fatty tissue of the fish, so removing as much fat as possible from fish before consuming it can reduce your exposure to PCBs in affected fish.

Risk

PCBs are known to be carcinogenic, yet they are also known to cause neurological damage to developing fetuses, and also affect the immune and reproductive systems. Because PCB levels tend to become more concentrated in larger fish, it is recommended to consume smaller species of fish. PCB contamination varies by the body of water in which the fish normally lives. Thus, there is not a comprehensive list of fish to avoid, nor a broad advisory as there is with mercury.

The Controversy

The concern over PCB levels in fish stem from the different standards used by the FDA and the EPA in determining a safe level of PCB content. The safe limit set by the FDA is 2,000 parts per billion (ppb), while the EPA has set a lower safe limit of 24 to 48 ppb.

PCB levels in fish made the news last year, when the Environmental Working Group (EWG), a nonprofit environmental research organization, stated that farm-raised salmon contained levels of PCBs that exceeded the EPA's safe limit. Scientists have since discredited this claim for two reasons: first, the EWG only tested 10 salmon fillets, a sample that may not represent all farm-raised salmon sold in the United States ; and the levels they discovered - 27 ppb -- fall well below the limit of 2,000 ppb set by the FDA. Furthermore, even though the EPA has set a lower standard of 24 ppb, the upper range in 48 ppb, so the 27 ppb discovered by the EWG does not exceed this range.

Thus, the controversy - why does the EPA have stricter guidelines, and are people being exposed to excessive levels of PCB in their fish? For more information on this issue, see the Tufts Health & Nutrition Letter article, "Is Farm-Raised Salmon Bad For Your Health After All?" November 2003 [healthletter.tufts.edu/issues/2003-11/salmon.html].

Bottom Line:

Most nutritionists agree that including fish is an important part of a healthy diet. If you are concerned about reducing the amount of contaminants, follow the FDA guidelines posted above. You will find that you can still include a good amount of fish in your diet and not miss out on their heart-healthy nutrients.

If you are concerned about consuming fish but still wish to obtain the health benefits associated with their omega-3 fatty acids, fish oils supplements could be an option for you. They are available at grocery stores and most health food stores. Consult a physician before starting fish oils supplements, as concentrated doses could have adverse effects on some people.

Fish Calculator

If you are curious about how much fish you may safely eat to avoid health risk, try the Fish Calculator by the Institute for Agriculture and Trade Policy:

http://www.iatp.org/foodandhealth/fishcalculator/index.cfm

References

Institute for Agriculture and Trade Policy

http://www.iatp.org/foodandhealth/fishcalculator/about.cfm

American Heart Association:

http://www.americanheart.org/presenter.jhtml?identifier=4632

FDA websites:

"Mercury Levels in Commercial Fish and Shellfish" http://www.cfsan.fda.gov/~frf/sea-mehg.html

FDA Advisory:

http://www.cfsan.fda.gov/~dms/admehg3.html

National Institutes of Health

Mercury Health Hazards

http://www.nih.gov/od/ors/ds/nomercury/health.htm

Environmental Protection Agency:

http://www.epa.gov/mercury/health.htm

http://www.epa.gov/waterscience/fish/advisories/factsheet.pdf

http://www.epa.gov/waterscience/fish/MethylmercuryBrochure.pdf

http://www.epa.gov/ost/fish/