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Fish, your Health and the Environment
Fish contains the important omega 3 fatty acids
called eicosapentanoic acid (EPA), a powerful anti-inflammatory and
anti-coagulant, and docosahexanoic acid (DHA) that is essential for
proper brain development and brain function. A healthy body can
manufacture EPA and DHA from other omega 3 fats such as are found in
flax, walnut and canola oil and in dark green, leafy vegetables.
However, this is carried out is several stages, each one enzyme
controlled and subject to disruption by many factors, and for this
reason most health practitioners recommend eating fish 3 – 5 times
weekly.
Factors that adversely influence EPA and DHA
production
- Chronic exposure to adrenalin and cortisol
(chronic stress, caffeine, television, anxiety etc)
- Aging
- Low protein intake
- Tobacco
- Environmental pollution and toxins
- Many recreational and prescription drugs
- Large intake of glucose
- Inadequate B6, magnesium and zinc in the diet
- Presence of excessive saturated fats in diet
- Presence of trans-fatty acids (processed / cooked fats and oils)
in the diet
- Atopic tendency (asthma, hay fever, eczema in the family)
- Diabetes
- Consumption of alcohol
- Ionizing radiation
Many of our rivers and oceans are contaminated with
mercury and industrial toxins and these can find their way into fish.
The larger the fish the higher the load of mercury because they eat
smaller fish and so concentrate the toxin. Shark, swordfish, King
mackerel, tuna, marlin and tilefish are the worst affected. These fish
should be eaten not more than twice per month. Shellfish generally have
the lowest mercury levels but because they are filter feeders they may
concentrate other toxins and should also be restricted to not more than
twice a month. Many industrial pollutants concentrate in fat so
broiling, grilling or baking fish on a rack to allow fat to drip off may
be helpful in reducing toxin exposure.
Many fish have been over-harvested and wild stocks are fast diminishing.
Atlantic cod, for example, is banned form commercial fishing due to loss
of numbers. Some fish are now farmed but this is generating many other
problems. Fish kept in captivity in overcrowded cages and denied the
opportunity to swim freely, are subject to many diseases such as fungal
infections, sea lice and bacterial infections. To prevent these diseases
the fish are routinely given anti-fungals and anti-biotics as well as
growth hormones to cause them to gain weight faster and other hormones
to prevent them maturing sexually and mating in the cages. Farmed fish
are fed corn and other grains as well as eating almost their own weight
in other fish and fish by-products, which are taken from the wild. Lack
of normal swimming patterns and normal diet cause the flesh of farmed
fish to be discolored and coloring agents are used, especially in
salmon. Farmed fish can pass disease to wild fish nearby and can escape
the cages and breed with wild fish thereby introducing weak genes and
further aggravating the loss of wild fish.
EATING FISH SAFELY
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Species |
Mercury status |
Environmental |
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Salmon
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Not significant
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Avoid farmed salmon. Choose coho, chinook and
sockeye for most good oils. |
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Halibut
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Moderate to high levels in Pacific and
Atlantic fish
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Atlantic halibut is endangered so choose
Pacific sources |
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Red snapper
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Moderate to high levels
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A threatened species, best avoided |
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Rainbow trout
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Fresh water species have more mercury than
ocean trout
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Often farmed – check labels |
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Tuna
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Moderate to high levels
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Bluefin has been over-harvested. Choose
yellowfin, albacore and bigeye. |
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Crab
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Dungeness has more mercury than blue crab
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Alaskan king crab is over harvested and
endangered. |
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Shrimp
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Very low levels
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Trap-caught spot shrimp and Northern shrimp
from Newfoundland are least likely to catch other marine
wildlife. |
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Oysters
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Very low levels
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Disease in the Eastern oyster beds is
limiting supply. Choose Pacific and European varieties. |
Sources: US Food and Drug Administration Center
for Food Safety and Applied Nutrition, Office of Seafood; Environmental
Defense Fund at www.environmentaldefense.org
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