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Fishing for Omega-3s
For: Ask the Experts, June 2002

The American Heart Association recently revised its dietary guidelines to advise eating at least two servings of fish a week. It emphasized fatty fish such as salmon and herring, since this is one instance where fat may help protect the heart.

The fat in fish is rich in polyunsaturated fatty acids called omega-3s, notably eicosapentenoic acid (EPA) and docosahexenoic acid (DHA). Omega-3s make platelets in the blood less likely to stick together and may reduce inflammatory processes in blood vessels (and elsewhere). Thus they reduce blood clotting, thereby lessening the chance of a fatal heart attack. Omega-3s can reduce triglycerides, the major type of fat that circulates in the blood. They may also make the heart less susceptible to dangerous, sometimes fatal, rhythm abnormalities. In addition, there's promising research showing that fish oil may help relieve inflammatory symptoms of auto-immune diseases such as rheumatoid arthritis or psoriasis.

Note on supplements

Fish-oil capsules have become increasingly popular, but they may not have the same benefits as fish. And they come with potential adverse effects, including an excessive reduction in the ability of your blood to clot, which increases the risk of hemorrhagic stroke. They may also raise cholesterol levels in some people. And they can cause nausea, diarrhea, belching, and a bad taste in the mouth. Consume fish, not capsules, unless your doctor has recommended them to treat, for instance, high triglycerides.

For pregnant women

In January the FDA warned pregnant women—and those who might become pregnant or who are nursing—not to eat shark, swordfish, king mackerel, or tilefish because these may contain mercury, which can damage the brain and nervous system of the fetus. It also advised pregnant women to eat no more than 12 ounces of fish a week, and to vary the types of fish they eat.

Which seafood has the most?

There are no U.S. government recommendations for omega-3 intake, but Health Canada, the Canadian counterpart of the FDA, recommends 1 to 1.5 grams a day. A "serving" of fish is small, just 3 to 4 ounces. Here are the numbers from USDA.

SEAFOOD		OMEGA-3s IN 3.5 OUNCES
EXCELLENT
Atlantic mackerel		2.6 grams
Lake trout		2.0
Atlantic salmon, farmed		1.9
Herring		1.8
Bluefin tuna		1.6
Chinook salmon		1.5
Sturgeon		1.5
Albacore tuna		1.5
Whitefish, lake		1.5
Sardines, canned		1.4
Bluefish, Atlantic		1.2
Salmon, pink		1.0
GOOD
Halibut, striped bass, mullet, pollock, catfish, rainbow trout, carp, shrimp, crab, lobster		0.4-0.9
FAIR
Sole, flounder, perch, cod, grouper, haddock, swordfish, red snapper, plaice, clams		less than 0.3

UC Berkeley Wellness Letter, April 2001