Shellfish : nutrition, amazing 2 medical uses & 4 adverse effects


(Abalone, clams, conch, crabs, crayfish, lobster, mussels, oysters, prawns, scallops, shrimp, snails)

Shellfish Nutritional Profile

• Energy value (calories per serving): Moderate
• Protein: High
• Fat: Low
• Saturated fat: Low
• Cholesterol: Moderate to high
• Carbohydrates: Trace
• Fiber: None
• Sodium: Moderate to high
• Major vitamin contribution: B vitamins
• Major mineral contribution: Iron (clams), iodine, copper, zinc (oysters), arsenic

How Many Nutrients in The Selfish

• Like meat, fish, poultry, and eggs, shellfish are an excellent source of high-quality proteins with sufficient amounts of all the essential amino acids required by human beings.

• Mollusks (abalone, clams, oysters, scallops, snails) are comparable in total fat content to meat and poultry. Crustaceans (crabs, lobster, shrimp) are lower in total fat content. Both types of shellfish have less saturated fat than meat does.

• They do have comparable amounts of cholesterol, but this is offset by the fact that like other seafood, shellfish provide omega-3 fatty acids, the class of heart-protective fats that include linolenic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA).

• Like other foods from animals, all shellfish are good sources of B vitamins, heme iron (the organic form of iron most easily absorbed by the body), and zinc. As an added bonus, they like other fish are rich in iodine, the mineral that protects against goiter (swelling of the thyroid gland).

• All shellfish provide B vitamins. The crustaceans crabs, lobsters, and shrimp also have vitamin A produced by their diet of carotenoid-rich green vegetation. A four-ounce serving of cooked Dungeness crab has 350 IU of vitamin A (9 percent of the RDA for a healthy woman, 7 percent of the RDA for a healthy man).

• Shellfish also have heme iron, the organic form of iron found in meat, fish, poultry, milk, and eggs, as well as the trace minerals copper and iodine. Oysters are a good source of zinc, a mineral that helps ensure the proper functioning of the male reproductive system.

How To Serve Nutritions In The Shellfish 

• Thoroughly cooked, to prevent food poisoning.

Diets That May Restrict or Exclude This Food

• Controlled-fat, low-cholesterol diet
• Low-protein diet
• Low-sodium diet

How To Buying This Food

Look for:

Clams, mussels, and oysters shucked or live in the shell. Live clams, mussels, and oysters should be tightly shut or closed with a snap when you touch them. Shucked clams, mussels, and oysters should be plump and shiny and smell absolutely fresh.

• There should be very little liquid in the container. Choose live crabs that are actively moving their legs around. Lump crabmeat should be pink and white (not tan or yellowed), and it should smell absolutely fresh, as should cooked crabs.

• Choose live lobsters and crayfish that look fresh, smell good, and are moving about actively. American lobsters come in four sizes: chicken (3/4–1 lb.), a quarter (1.25 lb.), large (1.5–2.25 lbs.), and jumbo (over 2.5 lbs.). Cooked lobsters should have a bright-red shell and a fresh aroma.

• If the tail curls back when you pull it down, the lobster was alive when cooked. Female lobsters, which have fluffy fins (“swimmerets”) at the juncture of the tail and body, may contain roe or coral that turns red when you cook the lobster.

• Choose dry, creamy, sweet-smelling scallops; unlike clams, oysters, and mussels, they can’t be kept alive out of the water. Sea scallops, the large ones, may be sold fresh or frozen; bay scallops, the smaller shellfish, are usually only sold fresh.

• Choose fresh shrimp and prawns that look dry and firm in the shell.
Choose tightly sealed cans of snails. In 1998, the FDA National Center for Toxicological Research released testing an inexpensive indicator called “Fresh Tag.” The indicator, to be packed with seafood, changes color if the product spoils.

NOTE: Because of the possibility of industrial and microbial contamination of waters, live shellfish should be gathered only in waters certified by local health authorities.

How To Storing This Food

• Refrigerate all shellfish and use as quickly as possible. Like other seafood, shellfish are extremely perishable once they are no longer alive, and their fats, which are higher in unsaturated than saturated fatty acids, will oxidize and turn rancid fairly quickly.

• As a general rule, live clams in the shell may keep for up to two weeks, oysters in the shell for five days, shelled scallops for a day or two, and mussels should be used the day you buy them.

• Regardless of these estimates, check the shellfish frequently to see that it is still alive and unspoiled. Cook live crabs and lobsters before storing them to prolong their storage time. Shrimps and prawns will also stay fresh longer if you cook them before storing them.

• Use within a day. If you wait longer, check frequently to see that the crustaceans still look and smell fresh.

You can read the spinach all the nutrition, benefits & tips

How To Preparing This Food

• when you are ready to prepare shellfish, sniff them first. if they don’t smell absolutely fresh, throw them out.


Tenderize the abalone meat by pounding, then trim off any dark parts, and slice the fish against the grain.


All clams are sandy when you bring them home. To get rid of the grit, wash the closed clams thoroughly under cold running water. Then either immerse them in a salty solution (about 1/3 cup salt to a gallon of water or sprinkle them with cornmeal and cover them with water.

Refrigerate the clams.

They will take in the salt water (or cornmeal) and disgorge sand Clams covered with salt water will be cleaned in about half an hour, and clams covered with cornmeal in about three hours. Before serving or cooking, discard any clams that are open or do not close immediately when you touch them or remain closed or float in the water.


Steam the conch or crack its shell. Open the shell and pull out the meat. Cut away and discard the stomach (it’s right in the middle) and the dark tail. Peel off the skin, slice the meat thin, and pound it to tenderize the meat. Rinse, pat dry, and cook.


To clean hard-shell crabs, cook them first. Then plunge the hot crabs into cold water to firm up the meat. Remove the tail, snap off the claws, and pull off the shell. Cut away the gills and the digestive organs in the middle of the body and pull the meat away from the skeleton. Soft-shell crabs should be washed in cold water. They are ready to cook when you buy them.

Lobsters and crayfish (live).

If you plan to boil the lobsters, you can cook them just as they come from the store. If you plan to broil a lobster, kill it first by inserting a knife into the space between the head and the body and slicing through the crustacean’s spinal cord. Then split the lobster and remove the internal organs.

• Live crayfish that have been stored in fresh running water does not have to be eviscerated before you boil them. If you wish to eviscerate the crayfish, grasp the middle fin on the tail, twist, and pull hard to pull out the stomach and intestine.


In the shell, mussels, like clams, are apt to be sandy. To get rid of the grit, scrub the mussels under cold running water, then put them in a pot of cold water and let them stand for an hour or two. Discard any that float to the top. Rinse the rest once more under cold running water, trim the “beard” with scissors, and prepare as your recipe directs.


Unlike clams and mussels, oysters in the shell are free of sand when you buy them. To prepare them, just wash the oysters thoroughly under cold running water. Discard any that don’t close tight when you touch them or that float in water. Cook them in the shell or pry open the shell, strain the liquid for any stray grit, and use the oysters with or without the shell, as your recipe directs.


Shelled scallops in bulk should be relatively free of liquid. Rinse them in cold running water and use them as your recipe directs.

Shrimp and prawns.

Wash the shrimp or prawns in cold running water. Then cook them in the shell to enhance the flavor of a soup or stew, or peel off the shell and remove the black “vein” (actually the digestive tract) running down the back, and prepare the shellfish as your recipe directs. (The orange line sometimes found running alongside the “vein” is edible roe.)

Snails (canned).

Prepare as your recipe directs. When you are done, clean all utensils thoroughly with soap and hot water. Wash your
cutting board, wood or plastic, with hot water, soap, and a bleach and water solution. For ultimate safety in preventing the transfer of microorganisms from the shellfish to other foods, keep one cutting board exclusively for fish, meat, or poultry, and a second one for everything else.

What Happens When You Cook This Food

• When you cook shellfish, heat changes the structure of its proteins. The protein molecules are “denatured,” which means they may break apart into smaller fragments, change shape, or clump together. All these changes force moisture out of protein tissues, making the shellfish opaque.

• The loss of moisture also changes the texture of the shellfish; the longer they are cooked, the more rubbery they will become. Shellfish should be cooked long enough to turn the flesh opaque and destroy any microorganisms living on the food.

How Other Kinds of Processing Affect This Food


When you freeze shellfish, the water in their cells forms ice crystals that can tear the cell membranes so the liquids inside leak out when the shellfish is defrosted which is the reason defrosted shellfish tastes tougher and has fewer B vitamins than fresh shellfish.

• Defrosting the shellfish slowly in the refrigerator, lessens the loss of moisture and B vitamins. Frozen shrimp and prawns can be boiled whole, in the shells, without defrosting.


Virtually all canned shellfish is higher in sodium than fresh shellfish. To reduce the sodium content, rinse the shellfish in cold water before you use it.

shellfish food

Amazing Medical Uses and/or Benefits

As a source of calcium.

Ground oyster shells, which are rich in calcium carbonate, are the calcium source in many over-the-counter supplements. Calcium carbonate is an efficient source of the mineral, but it is also likely to cause constipation.

Protective effects of omega-3 fatty acids.

Shellfish have small amounts of omega-3 fatty acids, a family of fatty acids which includes the essential fatty acid linolenic acid. Two other omega-3s, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), most abundant in fish living in cold waters, are the primary unsaturated fatty acids in oils from fish (anchovy, herring, mackerel, menhaden, salmon, sardines, trout, tuna) and shellfish, as well as human breast milk.

• The omega-3s appear to reduce the risk of heart attack and “sudden death.” A 20-year project at the University of Leyden in the Netherlands, comparing the eating habits of more than 800 men at risk of heart disease, found that men who ate more than an ounce of fish a day had a 50 percent lower rate of heart attacks. Since then, a lengthening list of studies has shown similar protection among men who eat fish at least two or three times a week.

• Possible explanations for this effect are the omega-3’s ability to lower the levels of triglycerides in your blood (high triglycerides are a risk factor for heart disease) and the fact that your body converts omega-3s to a compound similar to prostacyclin, a naturally occurring chemical that inhibits the formation of blood clots.

• In the United States, about 250,000 people die each year from sudden cardiac failure caused by ventricular fibrillation, an unexpectedly irregular heartbeat. Those most at risk are people with blocked arteries (atherosclerosis), congestive heart failure, or abnormal thickening of the heart muscle.

• In a 1995 study from the Australian Commonwealth Scientific and Industrial Research Organization (Adelaide), laboratory monkeys fed omega-3 oils from fish had a steady heartbeat when exposed to an electrical current twice as powerful as that which caused ventricular fibrillation in animals that did not get the fish oils.

• However, the heart benefits of the small amounts of omega-3s in shellfish such as shrimp may be offset by the high cholesterol content. 

• Omega-3s also inhibit the production of leukotrienes, naturally occurring chemicals that trigger inflammation. This may be beneficial to people with rheumatoid arthritis.

• In 1995, the Arthritis Foundation published the results of a study by Piet Geusens at the Catholic University in Pellenberg (Belgium) suggesting that patients who take omega-3 fatty acid supplements along with their regular arthritis medications have improved pain relief. Previous studies had demonstrated the omega-3s ability to reduce inflammation, joint stiffness and swelling.

• Finally, omega-3s may protect bone density. A 1997 study at Purdue University (Indiana) demonstrated that animals fed increased amounts of omega-3 fatty acids formed new bone faster than animals fed a regular diet. This result has also shown up in studies with soybeans.

Adverse Effects Associated with This Food

Allergic reaction.

According to the Merck Manual, shellfish are one of the 12 foods most likely to trigger classic food allergy symptoms: hives, swelling of the lips and eyes, and upset stomach.

• The others are berries (blackberries, blueberries, raspberries, strawberries), chocolate, corn, eggs, fish, legumes (green peas, lima beans, peanuts, soybeans), milk, nuts, peaches, pork, and wheat (see wheat cereals).

NOTE: Shrimp treated with sulfur compounds to prevent their darkening can cause serious allergic reactions in people sensitive to sulfites.

Food-borne infectious diseases.

In the past two decades, food scientists have identified an increasing number of bacteria and viruses, including the cholera organism, the hepatitis virus, and Vibrio vulnificus, in live shellfish.

• According to the Food and Drug Administration, Vibrio cholera organisms introduced when wastes are thrown into the ocean are now permanent residents along some parts of the Atlantic and Gulf coasts, found all the way from Maine to Texas.

• Cholera-contaminated shrimp and crabs have been found in Louisiana, contaminated blue crabs in Galveston, (Texas), and contaminated oysters in Florida. Shellfish from infected water may carry the hepatitis B virus; Vibrio vulnificus, another organism carried in shellfish, causes fever, chills, and shock.

• While it is true that cooking kills these organisms, the Centers for Disease Control which advises cooking ALL shellfish warns that viruses can survive quick steaming.

• The CDC further warns that raw shellfish are particularly hazardous for people with a weakened immune system: the very young, the very old, and those who are HIV-positive or undergoing cancer chemotherapy or have liver disease, diabetes, or chronic gastrointestinal disease.

• “Red Tide” poisoning. “Red tide” is a blanket of reddish organisms called dinoflagellates that float on the surface of the coastal waters of the Pacific and New England coasts between July and October.

• The dinoflagellates produce a neurological toxin that can be carried by any shellfish (clams, mussels, oysters) that eat the plankton. The toxin, which cannot be destroyed by cooking, can cause nausea, vomiting, and abdominal cramps, followed by muscle weakness and paralysis. Death may occur due to respiratory failure.

• These symptoms generally begin to appear within a half-hour after you eat the contaminated shellfish. Other
plankton ingested by shellfish may contain a diarrheic poison that causes gastric symptoms once thought to be caused by bacterial or viral food poisoning.

Worms or parasites.

Raw shellfish, like raw meat, maybe host to worms, parasites, or their eggs and cysts. These organisms are killed by cooking the shellfish until the flesh is completely opaque.

Production of uric acid.

Purines are the natural metabolic by-products of protein metabolism in the body. They eventually break down into uric acid, which may form sharp crystals that may cause gout if they collect in your joints or kidney stones if they collect in the urine.

• Shrimp are a source of purines; eating them raises the concentration of purines in your body. Although controlling the amount of purine-producing foods in the diet may not significantly affect the course of gout (which is treated with medication such as allopurinol, which inhibits the formation of uric acid), limiting these foods is still part of many gout regimens.


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