All About Clams

Clams (as well as mussels, oysters and scallops) are bivalve mollusks. Bivalves have two shells that are hinged together and have soft inside bodies. Found along the East and West Coasts of the U.S., both hard- and soft-shell clams are mildly salty and have a soft, chewy texture.

Nutritionally Speaking

Although health experts used to suggest limiting intake of clams and other shellfish because of their cholesterol content, current research indicates that the dietary cholesterol in clams and other shellfish don’t affect blood cholesterol levels as previously thought. Clams are very low in both total and saturated fat; 3 ounces of clams has just 73 calories and provides 12.5 grams of protein. Clams are naturally low in sodium, but canned clams contain added salt.

Shellfish allergies affect around 2% of people in the United States. Allergies to crustaceans (like shrimp or lobster) are more common than allergies to mollusks like clams. Reaction symptoms may be moderate to life-threatening and those who are allergic are usually advised to avoid all kinds of shellfish.

Growing

Clams are found burrowed in sandy or muddy bottoms of shorelines. Clams eat plankton and other microscopic organisms in saltwater and filter them through their gills. Atlantic hard-shell clams, often called by their Native American name quahog, include the large chowder clam with a shell diameter of at least 3 inches, medium-sized cherrystones, and small, tender littlenecks with a shell diameter of less than 2 inches. Hard-shell clams vary in size, with tenderness generally decreasing as size increases.

Along the West Coast, hard-shell varieties are medium to small and include the Pacific littleneck, Manila, Pismo and the small, sweet butter clam.

The most common softshell clam on the East Coast is the steamer clam. On the West Coast, razor clams have narrow shells that resemble old-fashioned straight razors. Another West Coast native is the anomaly known as the geoduck with a shell up to 7 inches long and a neck that can grow beyond its shell, up to 3 feet. Unlike soft-shell crabs, the brittle shells of soft-shell clams are inedible.

Availability

Farm-raised clams have little impact on habitats or other species. Wild-caught clams may be harvested by hand with rakes or shovels or by the less-sustainable commercial dredging method.

Purchasing

Fresh clams are purchased live in the shell, at fish markets or grocery stores. To test, tap the hard shell; the clam should close tightly. For soft shells, gently poke the neck and the clam should retreat slightly. Farm-raised fresh clams are usually cleaned and flushed of sand before they’re sold.

Clams also may be purchased frozen, raw or cooked, or in breaded strips. Canned clams are typically chopped and packed in their own briny juice.

Storing

Store live clams in a porous bag for up to two days in the refrigerator, but never store them in a plastic bag or submerged in water. Freshly shucked clams can be stored up to 10 days.

Canned clams can be stored for a year; once opened, store in the fridge and eat within a day or two. For quality, you can keep frozen clams in the freezer for two to three months.

Preparing

To remove the sand in wild-caught clams, cover them with cool tap water in a large bowl. Let the clams sit for 20 minutes to an hour to allow them to filter out sand. Adding cornmeal or black pepper to the water may encourage the clams to spit out more sand. Gently remove clams from the water and scrub the outer surface before cooking.

It’s important to properly prepare fresh clams in order to minimize food safety risk. Before cooking, discard dead clams (those that don’t respond when tapped) and those with cracked or chipped shells. Throw away those that do not open. Shells should open as the clams cook, which indicates they are safe to eat. Eating raw shellfish can be risky and potentially cause an infection called vibriosis.

Using

Serve clams as appetizers, salad toppers, in chowders and stews, and in pasta dishes and seafood bakes. Cooked clams may be served in or out of the shell. Cook clams gently to prevent toughness. Try steaming them in a small amount of water, wine or broth with added garlic, parsley or other seasonings.

Clams can be served in the shell or removed and tossed with hot pasta, deep-fried, used in stuffing mixtures, or added to soups such as the tomato-based Manhattan or cream-based New England clam chowders. Simulate a traditional New England clam bake by layering onions, potatoes, corn cobs, sausage, lobster, shrimp and clams in a large stockpot. Spanish seafood paella, flavored with saffron and served with rice, typically includes clams.

This information originally appeared in Food & Nutrition Magazine^®, published by the Academy of Nutrition and Dietetics.