Fish and shellfish are high in protein and nutrients and are an important part of a healthy diet, but it is important to properly purchase, handle and prepare fish so that illness, or death, does not occur. Eating some types of fish can cause ill effects in some groups of people and the U.S. Food and Drug Administration (FDA) advises consumers not to eat them.
Shark, Swordfish, King Mackerel, Tilefish
Women who are pregnant or might become pregnant, nursing mothers and young children should avoid eating these fish as they contain high levels of mercury. Consuming too much mercury can harm the nervous system of unborn babies and young children. Mercury is naturally present in the environment and is released into the air by industrial pollution. When mercury falls into streams and oceans, it turns into methylmercury and is absorbed by the fish. These types of fish are large and live a long time so they have accumulated larger amounts of mercury than other types of fish.
Puffer fish also called puffer, bok, fugu, blowfish, swellfish, globefish, sea squab or balloonfish can be deadly to eat. Puffer fish contain deadly toxins called saxitoxin and tetrodotoxin, which affect the central nervous system and can cause severe illness and death. Symptoms are tingling in the mouth, lips and extremities, dizziness, muscle weakness and paralysis, vomiting, diarrhea, problems with speaking and balance. Symptoms can begin within 20 minutes to 2 hours after consuming the toxic fish. In severe cases, respiratory paralysis can occur which can lead to death. To keep from contaminating the flesh of the fish with the toxin, proper and careful removal of the skin, intestines, liver, ovaries or testes of the fish is crucial as these organs contain the toxin.
Harvesters and processors of clams, oysters and mussels are required to attach a safety control label to the containers of shellfish. When purchasing these products, consumers should check the label to make sure that the guidelines have been followed. In addition, do not purchase or eat clams, mussels or oysters with cracked or broken shells or if they do not close up after tapping on the shells. Live crabs and lobsters should show some movement in the legs and if there is none, it may be a sign that they are dead. Do not purchase or eat these if there is no leg movement as they spoil quickly after death.
Women who are pregnant, young children, older adults, persons with a compromised immune system or persons with decreased stomach acidity should avoid eating raw or partially cooked seafood. This group of people is at a greater risk for contracting a food borne illness. Eat only previously frozen raw seafood as some fish contain parasites and freezing kills the parasites. Freezing does not kill all of the harmful microorganisms, so it is always best to cook seafood.
Women who are pregnant, older adults and people with weakened immune systems are at risk for contracting a food borne illness called Listeriosis disease from eating smoked seafood. Refrigerated types of smoked seafood such as trout, salmon, cod, tuna, mackerel and whitefish that is labeled nova-style, kippered, smoked, lox or jerky should be avoided. Canned or shelf type smoked seafood is safe to eat.