from Harvard Medical School Healthbeat

We know that fish is a source of high quality, low calorie protein.  And that salmon has the advantage of also offering omega-3 fats.  And that top feeders like swordfish and sharks contain undue amounts of mercury and other contaminants.

But how does shellfish stack up to fish?

Omega-3s   Lobster, shrimp and clams have little of the healthy fat, and calamari, blue crab and oysters have about one-fourth as much as salmon.  Still, they contribute about a gram of Omega-3s, which is pretty good.

Protein   Ounce for ounce, shellfish have about the same amount of protein as salmon.  Octopus, though, has the highest level of protein among the 10 species evaluated for this article.

Cholesterol   For most people, saturated fat has a bigger effect on our blood cholesterol than does the cholesterol we eat.  Some people, though, are “cholesterol responders,” meaning their blood cholesterol levels are greatly impacted by the cholesterol they consume.  Those people would be wise to go easy on shrimp, with166 mg/3 ounces and on fried calamari, with 221 mg/3 ounces.

However, here’s a cholesterol-lowering bonus:  Clams, crab, mussels and oysters contain sterols that interfere with the absorption of cholesterol.

Calories   Both shellfish and regular fish are low in calories—unless they’re fried or breaded.

Nutritional Pluses   Oysters top the list as a food source for zinc.  Clams have abundant iron and vitamin B12.  Crustaceans (lobster, crab, shrimp) supply an obscure nutrient, choline, which accelerates the synthesis of a neurotransmitter vital to memory and muscle control.

Toxins   About 2% of the population have food allergies, most related to shellfish or mollusks.  The prevailing opinion is that those who are allergic to one of those fish groups should avoid both.

For more information about Omega-3s and heart health, go to



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