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FDA Brochure: May 1993
IMPORTANT HEALTH INFORMATION FOR PEOPLE WITH LIVER DISEASE
Protect Yourself: Only Eat Fish That's Been Thoroughly Cooked
This brochure is to inform people with liver disease of the
hazards they face if they eat raw molluscan shellfish-oysters,
mussels, clams, and whole scallops. The brochure also contains
useful information about safe handling and consumption of seafood
in general.
Fish-fin fish and shellfish-have many of the qualities that
health-conscious food shoppers look for. They're generally low in
saturated fat and are excellent sources of protein, vitamins and
minerals, although nutrition values differ depending on the
type.Properly handled and thoroughly cooked, fish is tender, easy
to digest, and safe to eat.
But sometimes shellfish, especially mollusks--oysters, clams,
mussels, and whole scallops--are eaten raw, as in oysters-on-the-halfshell.
Eating raw or undercooked shellfish can a be serious
problem for persons with:
- Liver disease, including cirrhosis, hemochromatosis, and
chronic alcohol use
- Diabetes mellitus
- Immune disorders, including AIDS, cancer, and reduced
immunity due to steroid or immunosuppressant therapy
- Gastrointestinal disorders, including previous gastric
surgery, and low gastric acid (for example, from antacid use or
achlorhydria).
The problem occurs because raw mollusks sometimes carry
bacteria called Vibrios that may multiply after the shellfish are
caught, even with refrigeration. These bacteria are completely
killed when the shellfish are thoroughly cooked, removing all
danger od the bacteria causing food poisoning.
But if the mollusks are eaten raw or partially cooked, the
bacteria remain alive and may make you very sick. Symptoms often
include one or more of the following: fever, chills, diarrhea,
confusion, weakness, cellulitis (certain regions of the skin
turning red and painful), and enlarging bloodfilled or clear
blisters (most often on legs). You should be evaluated by your
physician if you experience any of these symptoms within five
days after eating raw or undercooked molluscan shellfish.
Infection with some Vibrios can cause blood poisoning, a
condition that has resulted in death in up to half the people who
get it. Death usually occurs within two days after the illness
starts.
Certain viruses known as Norwalk viruses also could contaminate
oysters, clams and mussels and cause severe diarrhea in those who
eat them. Here again, thorough cooking kills the virus.
How Do Mollusks Get Contaminated?
Mollusks usually live where rivers and seas meet. Because many
cities are located near those places, the waters are more likely
to be polluted that offshore waters. For this reason, shellfish
harvesting is prohibited in areas contaminated by sewage. To
enforces this, these areas are patrolled by state health and
fishery agencies.
Mollusks feed by filtering water through their systems, so they
are more likely to pick up and store bacteria or viruses from the
water, including those that van cause illness in humans. If you
eat mollusks raw, you eat the live viruses and bacteria too.
Another source of contamination of shellfish can come from
naturally occurring algae blooms called "Red Tides." Waters are
closely monitored for those blooms to prevent shellfish poisoning
in humans. The Food and Drug Administration and the coastal
states all test for these blooms, and when they appear, the
waters are closed to all fishing.
Is Raw Fin Fish Safe to Eat?
Raw fish dishes, such as sushi and sashimi, can be safe for most
people to eat if they are made with very fresh fish, commercially
frozen (at temperatures lower than in home freezers), and then
thawed before they're eaten. This kills any parasites that may be
present.
Parasites are also killed by thorough cooking, and, once
killed, they are no longer a danger to you. But people with liver
disease should not eat raw fin fish because freezing does not
kill bacteria. Persons with liver disease need to take extra
precautions to thoroughly cook all fish.
For more information on seafood safety, purchasing and handling,
call the FDA Seafood Hotline at (1-800)FDA-4010 (or 202-205-4314
in the Washington, D.C., area).
Seafood Safety Tips
Shopping
- Fresh seafood should not smell unpleasantly "fishy." It
should smell like a "fresh ocean breeze."
Fresh fish steaks and fillets should be moist, with no drying
or browning around the edges. The eyes of fresh whole fish should
be bright and clear, not cloudy or sunken. Scales should not be
"slimy" and should cling tightly to the skin. Gills should be
bright pink or red. Frozen fish should not be freezer burned or
have damaged packaging.
- Mollusks in the shell should always be alive when you buy them.
When a clam, oyster, mussel, or scallop is alive, the
shells will be tightly closed or will close when tapped lightly
or iced. A test for freshness is to hold the shell between your
thumb and forefinger and press as though sliding the two parts of
the shell across one another. If the shells move, the shellfish
is not fresh. Throw away any that do not close tightly.
- Buy seafood only from reputable dealers. You can't know what
you're buying from the back of a pickup truck. It could have been
caught by someone not subject to FDA or state inspection.
- Ask to see the shipper's tag for molluscan shellfish.
- Cook fish no later than two days after purchase.
Storing
- Keep fresh fish cold--in the coldest part of your
refrigerator, usually under the freezer or in the meat drawer,
until it's ready to cook and serve.
- Store fresh fish in your refrigerator in the same wrapper it
had in the store.
Store live mollusks in your refrigerator in containers covered
loosely with a clean, damp cloth. Do not store live shellfish
in airtight containers or in water.
- Canned fish should be stored in a clean, covered glass or
plastic container and refrigerated after opening.
- Smoke fish, pickled fish, vacuum-packed fish, andmodified-atmosphere
packed fish products should always be refrigerated.
- Keep cooked and raw seafood separate. It's not safe to put
cooked seafood back in the original container used for raw
seafood, or to store raw and cooked seafood together.
Cooking
- The safest way to thaw frozen seafood is in the refrigerator
in its own container. Allow about one day for defrosting.
- For fin fish (baked, broiled, poached, fried, or stewed):
allow 10 minutes cooking time for each inch of thickness. Turn
the fish over halfway through the cooking time unless it is less
that a half an inch thick. Add 5 minutes to the total cooking
time if the fish is wrapped in foil or cooked in a sauce.
Properly cooked fish will flake easily with a fork and should be
opaque and firm. It should not be translucent.
- For molluscan shellfish: Boiled--shells will open during
boiling. After shells open, boiling should continue 3 to 5 more
minutes. Steamed-- cook 4 to 9 minutes from the start of
steaming.
- Use small pots to boil or steam shellfish. If too many shells
are cooking in the same pot, it's possible that the ones in the
middle won't get thoroughly cooked. Discard any clams, mussels or
oysters that do not open during cooking. Closed shells may mean
they have not received adequate heat.
- Shucked oysters: Boil or simmer for at least 3 minutes. Fry
in oil at least 10 minutes at 375 degrees Fahrenheit. Bake at
least 10 minutes at 450 F.
Following these steps for buying, storing and cooking will
protect you and still allow you to enjoy seafood.
Keep cold seafood cold: 40 degrees and below
Keep hot seafood hot: 140 degrees or avove
Avoid the DANGER ZONE
DHHS Publication No. (FDA) 93-2266, May 1993