Fish is a good source of protein and, unlike fatty meat products, it’s not high in saturated fat. It’s also a good source of omega-3 fatty acids, which benefit heart health.
The American Heart Association recommends eating fish at least twice a week. However, some types of fish may contain high levels of mercury, PCBs (polychlorinated biphenyls), dioxins and other environmental contaminants. Levels of these substances are generally highest in older, larger, predatory fish and marine mammals. Levels of mercury and omega-3 fatty acids for various fish and shellfish are shown below.
The benefits and risks of eating fish vary depending on a person’s stage of life.
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Children and pregnant women are advised by the U.S. Food and Drug Administration (FDA) to avoid eating those fish with the potential for the highest level of mercury contamination (e.g., shark, swordfish, king mackerel or tilefish); to eat up to 12 ounces (two average meals) per week of a variety of fish and shellfish that are lower in mercury (e.g., canned light tuna, salmon, pollock, catfish); and check local advisories about the safety of fish caught by family and friends in local lakes, rivers and coastal areas.
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For middle-aged and older men and postmenopausal women, the benefits of fish consumption far outweigh the potential risks when the amount of fish are eaten is within the recommendations established by the FDA and Environmental Protection Agency.
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Eating a variety of fish will help minimize any potentially adverse effects due to environmental pollutants.
Potential exposure to some contaminants can be reduced by removing the skin and surface fat from these fish before cooking. Consumers should also check with local and state authorities about types of fish and watersheds that may be contaminated, and should also see the FDA Web site for the most up-to-date information on recommendations for specific subgroups of the
U.S.
population (e.g., children, pregnant women).
Top 10 fish and shellfish consumed in the United States
|
Mean mercury level in parts per million (ppm) |
Omega-3 fatty acids
(grams per 3-oz. serving) |
Canned tuna (light) |
0.12 |
0.17–0.24 |
| Shrimp |
ND* |
0.29 |
| Pollock |
0.06 |
0.45 |
| Salmon (fresh,frozen) |
0.01 |
1.1–1.9 |
| Cod |
0.11 |
0.15–0.24 |
| Catfish |
0.05 |
0.22–0.3 |
| Clams |
ND* |
0.25 |
| Flounder or sole |
0.05 |
0.48 |
| Crabs |
0.06 |
0.27–0.40 |
| Scallops |
0.05 |
0.18–0.34 |
Other common seafoods
|
Mean mercury level in
parts per million (ppm) |
Omega-3 fatty acids
(grams per 3-oz. serving) |
| Lobster |
0.31 |
0.07–0.46 |
| Grouper |
0.55 |
0.23 |
| Halibut |
0.26 |
0.60–1.12 |
| Oysters |
ND* |
0.37–1.14 |
| Mahi mahi |
0.19 |
0.13 |
| Herring |
0.04 |
1.9–2.0 |
Fish with the highest levels of mercury (about 1 ppm Hg)
| |
Mean mercury level in
parts per million (ppm) |
Omega-3 fatty acids
(grams per 3-oz. serving) |
| Shark |
0.99 |
0.83 |
| Swordfish |
0.97 |
0.97 |
| Tilefish (golden bass or golden snapper) |
1.45 |
0.90 |
| King mackerel |
0.73 |
0.36 |
Advice from the FDA
Women who are pregnant, planning to become pregnant or nursing — and young children — should not eat these fish. Everyone else can eat up to 7 ounces of high-mercury fish per week.
Fish with about 0.5 ppm Hg
|
Mean mercury level in parts per million (ppm) |
Omega-3 fatty acids
(grams per 3-oz. serving) |
| Fresh or frozen tuna |
0.38 |
0.21–1.1 |
| Red snapper |
0.60 |
0.29 |
| Orange roughy |
0.54 |
0.028 |
Advice from the FDA
Minimizing exposure to methylmercury is particularly important for pregnant women, women who are planning to become pregnant, nursing women and young children. These people should limit their consumption of all fish with much lower mercury levels than 1 ppm Hg (see above). The guideline for them is 12 ounces per week (about 3 to 4 servings). Other people can eat 14 ounces a week of fish with mercury levels that average 0.5 ppm.
* ND – mercury concentration below the Level of Detection (LOD=0.01ppm)
Related AHA publications/Web pages:
