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Shellfish: Are They Good for You or Not?
Here's the Answers You Need

Americans enjoy an average of 16 pounds of seafood and shellfish every year. Among its chief benefits, seafood is a high-quality source of protein, is low in fat, rich in many vitamins and minerals. Seafood is also the source of most of the omega-3 fatty acids DHA and EPA -- which may help prevent heart disease and more -- in the American diet, according to the Institute of Medicine.

raw shellfish

Raw shellfish accounts for over 90 percent of cases of seafood poisoning.

Raw shellfish, however, is also one of the food groups most likely to cause food-borne illness. According to the Centers for Disease Control and Prevention (CDC), "Because filter-feeding shellfish strain microbes from the sea over many months, they are particularly likely to be contaminated if there are any pathogens in the seawater."

Meanwhile, seafood in general has received a lot of bad press recently because of pollutants like mercury, PCBs, and dioxins, which may contaminate the flesh and cause health problems in humans.

Still, shellfish including oysters, clams, mussels, scallops, shrimp, and more are enjoyed by millions of Americans every year ... but are the potential risks worth it?

The Pros and Cons of Shellfish

From a nutritional perspective, shellfish can be a healthy part of your diet. From a contamination perspective, there may be some risk involved, even outside of the potential for mercury, PCBs and dioxins.

It's estimated that 20 million Americans eat raw shellfish, according to the U.S. Food and Drug Administration (FDA), and this accounts for over 90 percent of cases of seafood poisoning.

"The biggest seafood hazard by far is raw or undercooked shellfish," says Morris Potter of the CDC.

eating shellfish

Though cooking shellfish will eliminate some of the health risks, some toxins, such as the shellfish toxins below, are not eliminated by cooking.

"One has to bear in mind that when you eat raw shellfish you're eating a whole living organism complete with its GI tract," Potter said. "That would be equivalent to plucking a live chicken and eating it whole, guts and all."

The primary risks of shellfish include:

  • Norwalk virus, which comes from human sewage. It can cause nausea, vomiting and diarrhea, and symptoms usually resolve in a few days.

  • Vibrio: Vibrio infections from eating raw shellfish have increased a whopping 78 percent in the last decade, according to the CDC. Vibrio is a bacteria common to the warm waters of the Gulf of Mexico, and seafood that comes out of that region is likely to contain it.

    "Each year in the United States, Vibrio cause an estimated 8,000 infections and 50 deaths," said Dr. Nicholas A. Daniels of the University of California, San Francisco.

  • Shellfish Toxins: Marine organisms called dinoflagellates or diatoms are sometimes eaten or filtered by shellfish. These organisms produce toxins that concentrate in the bodies of shellfish. Though rare (the CDC estimates that 30 cases of poisoning by marine toxins are reported in the United States each year), eating contaminated raw shellfish can lead to:

    • Paralytic Shellfish Poisoning (PSP), which, in severe, cases, can cause paralysis, respiratory failure and death in two to 25 hours.

    • Diarrheic Shellfish Poisoning (DSP), which causes diarrhea, nausea and vomiting that typically resolve in a couple of days.

    • Neurotoxic Shellfish Poisoning (NSP), which causes numbness, tingling in the arms and legs, loss of coordination, muscle aches and upset stomach, all of which typically resolve in two to three days.

    • Amnesic Shellfish Poisoning (ASP), which can result in permanent short-term memory loss, seizures, paralysis and even death in severe cases.

  • Hepatitis A, which typically only causes a mild, short-term infection (you can have it and not even realize it).

So Should You Give Up, or Indulge in, Shellfish?

The answer is up to you. Many Americans do eat and enjoy shellfish without becoming ill, but there is risk involved, particularly if you intend to eat it raw.

Cooking shellfish will help to eliminate many, though not all, of the risks.

Some people, however, are at higher risk of severe infections should they come into contact with a contaminated clam or oyster, and therefore should avoid eating all shellfish. This group includes:

  • Pregnant women

  • The elderly

  • People with compromised immune systems

  • People with liver disease or kidney problems

Recommended Reading

What are the Least Safe Foods From a Contamination Perspective?

Are Oysters Really Aphrodisiacs?


CDC: Travelers' Health

NOAA Fisheries

Nutrition Action Healthletter

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