This Facts About lists common fish & seafood with an emphasis on those choices with high omega-3 content. We make recommendations on how to avoid toxins and choose fish & seafood that support sustainable fisheries. We provide a guide for selecting appropriate portion sizes and recommendations for incorporating healthy choices into your diet.

What are the recommended servings of fish & seafood?

• Optional: 2-4 servings per week, including at least 2 servings of fish with high omega-3 content
  • Serving size 4-6 ounces

Why should you choose fish & seafood?

• Low in saturated fat
• Rich source of protein and iron
• Contains B-12 vitamins
• Richest source of omega-3 fatty acids may be helpful in the prevention and treatment of: heart disease, high blood pressure, inflammation, mental health disorders, diabetes, digestive disorders, autoimmune disease, and cancer

Selected Food Sources with Serving Size*

Selected Fish and their Omega-3 Fatty Acid Content (2.0 g and above per serving)  

Selected Fish and Seafood with Moderate-Low Omega-3 Fatty Acid Content (less than 2.0 g per serving)

* Omega-3 content of various fish and seafood sources are averages and may depend on factors such as time of year of harvest and body of water in which the animal resides.  Values should be used for comparison of relative amounts in fish and seafood sources of omega-3 fatty acids.

Special Considerations

Choosing Fish & Seafood

• Seafood should not smell "fishy" but rather like a "fresh ocean breeze"
• Mollusks should always be alive when purchased with the shells. Shells should be tightly closed or close tightly when gently tapped.
• Use fresh fish no later than 2 days after purchase
• For long-term storage, fish must be frozen
• Fish is fully cooked when the flakes separate easily; about 10 minutes of cooking time per 1 inch of thickness

What are omega-3 fatty acids?

Omega-3 fatty acids are a type of polyunsaturated fatty acid (PUFA). They are an essential component of the human diet because our bodies can not make them. These fats are necessary for proper brain growth and development. Omega-3s are most abundant in deep-water fatty fish and some plant foods. They are anti-inflammatory and may be helpful in the prevention and treatment of numerous conditions.

Which fish should you eat to get the greatest benefits of omega-3 fatty acids?

Omega-3 fatty acid content varies greatly among different species of fish. Cold-water fatty fish have the highest content of omega-3 fatty acids because their physiology, environment and diet promote omega-3 fatty acid production in their flesh.
All fish contain some amount of omega-3s, however quantities vary among species and within a species according to the same factors mentioned above, i.e. environment and diet.

What is the daily recommended intake of omega-3 fatty acids?

There are currently no established guidelines regarding optimal omega-3 intake. According to the Institute of Medicine, the Adequate Intake (AI) is 1.1g daily for women and 1.6 g daily for men. Although some experts believe that these recommendations might be too low to obtain the health benefits associated with omega-3s. Research shows benefits associated with higher intake of 2-3 g per day.

Why is the fat ratio important?

Two types of fatty acids that are essential for human health are omega-3 and omega-6. Studies suggest that decreasing the ratio of omega-6 (in vegetable oils) to omega-3 fatty acids (in fatty fish) is important to reduce risk of cancer and heart disease, inflammatory conditions, and depression.

Most people consume too many omega-6 fatty acids and consume too little omega-3 fatty acids. To reduce your risk of chronic disease, reduce your intake of omega-6 fatty acids and increase your intake of omega-3 fatty acids.

• Avoid vegetable oils such as corn or safflower oil.
• Eliminate highly processed foods.
• Eat high omega-3 fish at least twice per week.

Know Your Limits for Fat

• On a 2,000 calorie diet, about 30% or 600 calories (67g) should come from total fat per day
• A ratio of 1:2:1 of saturated: monounsaturated: polyunsaturated (such as Omega-3s) fat is recommended
• 1:2:1 in calories equals 150:300:150; no more than 150 calories or 7.5% (17g) of total calories from saturated fat

Potential Chemical Contaminants

Risk of Mercury Poisoning

Mercury is a toxic heavy metal that can accumulate in fish.  Eating fish with high levels of mercury can negatively impact brain development in children and can affect learning and memory function in adults. Certain fish species are known to have higher mercury concentrations than others, sometimes due to polluted waters. The highest levels of mercury and contaminants tend to accumulate in the large predatory fish at the top of the food chain.

Avoid in pregnancy and in young children*

Shark

Swordfish

King mackerel

Tilefish

Limit intake in children as well as pregnant and nursing women**

Albacore tuna
Bass (Sea and Largemouth)
Bluefish
Grouper
Halibut
Lobster
Marlin
Red snapper
Pike
Orange roughy
Spanish mackerel
Walleye

Low levels of mercury-containing fish**

Anchovies
Atlantic mackerel
Catfish
Cod
Canned light tuna
Haddock
Herring
Mahi mahi
Pollock
Salmon
Sardine
Shad
Shrimp
Trout
Whitefish

Advice from the EPA for women who are pregnant, planning to become pregnant or nursing:

• *Do not eat shark, swordfish, king mackerel, or tile fish because they contain high levels of mercury. Everyone else can eat up to 6 ounces of high-mercury fish per week.
• ** Eat up to 12 ounces per week (about 3 to 4 servings) of a variety of fish and shellfish that are lower in mercury
• Five of the most commonly eaten fish that are low in mercury are shrimp, canned light tuna, salmon, pollock, and catfish.
• A commonly eaten fish, albacore ("white") tuna contains higher levels of mercury than canned light tuna because these fish are larger. Limit consumption to 6 ounces of albacore tuna per week.
• For further information about the safety of locally caught fish and shellfish, visit the Environmental Protection Agency's Fish Advisory website www.epa.gov/ost/fish. If no advice is available, eat up to 6 ounces per week of fish you caught from local waters, but don't consume any other fish during that week.
• Follow these same recommendations when feeding fish and shellfish to your young children, but serve smaller portions

Risk of PCB Exposure

PCBs (polychlorinated biphenyls) are industrial pollutants that find their way into fresh waters and oceans where they are absorbed by fish. A recent study reported unacceptable levels of PCBs in fish feed given to farmed salmon. The study reported that PCB levels in farmed salmon, especially those in Europe, were about seven times higher than in wild salmon. PCBs are potential human carcinogens, known to promote cancer in animals. Other potential health effects include impaired memory and learning, and adverse effects on the immune, reproductive and nervous systems. Until more research results are available, it may be prudent to choose wild salmon over farmed salmon and eat a wide variety of fish, along with plant sources of omega-3s. You can reduce PCB exposure from fish by removing the skin and visible fat as well as baking, broiling or grilling fish instead of frying.

Farmed vs. Wild

The old adage “you are what you eat” applies even if you are a fish.  The location and living conditions where fish and seafood live can affect what they eat and their exposure to chemicals.  In some studies, farm-raised fish have been shown to contain higher levels of contaminants compared to fish caught from the wild.  However, there are some ethical fish farms that take good care of their fish and limit contaminant exposure.  Recommendations have not yet been established for farmed vs. wild fish and seafood sources although the EPA has limited fish consumption in vulnerable populations such as children and women of childbearing age.  Talk to the person you buy your fish and seafood from to better understand this issue.

Incorporating High Omega-3 Fish into Your Diet

1. Order a variety of fish in restaurants and avoid fish that is fried or dipped in batter.
2. Experiment with fish recipes to replace red meat and other high fat choices.
3. Look for wild salmon at your local health food stores.
4. Mix canned sardines with your own combination of chopped red onion, avocado, hard-cooked eggs, lemon juice, salt and/or pepper.
5. Add chopped anchovies to pasta sauce just after you sauté your onions and garlic; the fish will melt away while leaving a mild, subtle fishy taste to your sauce.
6. When buying canned products, look for fish packed in water or olive oil (preferably, extra-virgin).
7. Cook with either dry or moist heat methods; poached, steamed, grilled, baked, or broiled are preferred.
8. Avoid fish that is battered and fried, slathered in butter, or blanketed in creamy sauces to reduce saturated fat and calorie intake.

This Facts About document is published by Monica Myklebust, MD, and Jenna Wunder, MPH, RD, at University of Michigan Integrative Medicine Clinical Services. Our mission is to care for people using an Integrative Medicine model that reaffirms the importance of relationship between practitioner and patient, focuses on the whole person, is informed by evidence, and makes use of all appropriate therapeutic approaches to achieve optimal health and healing.

Resources

Fish and Omega-3 Fatty Acids
American Heart Association
www.americanheart.org
Accessed May 17, 2006

Fish, Levels of Mercury and Omega-3 Fatty Acids
American Heart Association
www.americanheart.org
Accessed May 17, 2006

Bennion M and Scheule B. Introductory Foods. Upper Saddle River, NJ : Prentice-Hall, Inc.:2000.

National Listing of Fish Advisories
U. S. Environmental Protection Agency
http://epa.gov/waterscience/fish/advisories/fs2004.pdf
Accessed May 17, 2006

Organic Food Standards and Labels:  The Facts
U. S. Department of Agriculture
Agricultural Marketing Service
www.ams.usda.gov
Accessed May 17, 2006

Polychlorinated Biphenyls (PCBs)
U. S. Environmental Protection Agency
www.epa.gov
Accessed May 17, 2006

A Primer on Fats and Oils
American Dietetic Association
www.eatright.org
Accessed May 17, 2006

Summary - PCBs in Farmed Salmon
Environmental Working Group
www.egw.org
Accessed May 17, 2006

Original Research and Review Articles

Bayen S, et al.  Effect of cooking on the loss of persistent organic pollutants from salmon.  Journal of Toxicology and Environmental Health.  2005;68:253-265.

Calder PC, et al.  Polyunsaturated fatty acids, inflammation and immunity.  European Journal of Clinical Nutrition.  2002;56(suppl 3):s14-s19.

De Caterina R, et al.  Nutritional mechanisms that influence cardiovascular disease.  American Journal of Clinical Nutrition .  2006;83(suppl):421s-426s.

Fernandez E, et al.  Fish consumption and cancer risk.  American Journal of Clinical Nutrition.  1999;70:85-90.

Foran JA, et al.  Risk-based consumption advice for farmed Atlantic and wild Pacific salmon contaminated with dioxins and dioxin-like compounds.  Environmental Health Perspectives.  2005;113(5):552-556.

Gochfeld M, et al.  Good fish/bad fish:  a composite benefit-risk by dose curve.  NeuroToxicology.  2005;26:511-520.

Hites RA, et al.  Global assessment of organic contaminants in farmed salmon.  Science.  2004;303:226-229.

Kris-Etherton PM, et al.  Fish consumption, fish oil, omega-3 fatty acids, and cardiovascular disease.   Circulation. 2002;106:2747-2757.

Lombardo YB, et al.  Effects of dietary polyunsaturated n-3 fatty acids on dyslipidemia and insulin resistance in rodents and humans.  A review.  Journal of Nutritional Biochemistry.  2006;17:1-13.

Nestel PJ.  Fish oil and cardiovascular disease:  lipids and arterial function.  American Journal of Clinical Nutrition.  2000;71(1):228-231.

Simopoulos AP.  Essential fatty acids in health and chronic disease.  American Journal of Clinical Nutrition.  1999;70(suppl):560s-569s.

Simopoulos AP.  Human requirement for n-3 polyunsaturated fatty acids.  Poultry Science.  2000;79(7):961-970.

Simopoulos AP.  Omega-3 fatty acids in inflammation and autoimmune diseases.  Journal of the AmericanCollege of Nutrition.  2002;21(6):495-505.

Terry P, et al.  Fish consumption and breast cancer risk.  Nutrition and Cancer.  2002;44(1):1-6.

Terry PD, et al.  Intakes of fish and marine fatty acids and the risks of cancers of the breast and prostate and of other hormone-related cancers:  a review of the epidemiologic evidence.  American Journal of Clinical Nutrition.  2003;77:532-543.

Valensi, P.  Hypertension, single sugars and fatty acids.  Journal of Human Hypertension.  2005;19:s5-s9.