Fish, Omega-3 Fatty Acids, the Environment and Your Health
High mercury fish include swordfish, shark, mackerel, tuna. Some studies have found that
farmed salmon have higher levels of pesticides than wild salmon. Bottom line: Limit yourself
to 12 oz fish per week (from stores or restaurants, not local lakes). Vary your intake.
Check local advisories periodically.
Choose fish lower on the food chain, which include cod, whitefish, pollock, mahi-mahi, ocean perch,
halibut, haddock, flounder, sole, and all shellfish.
The Wellness Letter (4/04) notes that farm grown salmon is high in PCBs
(organic pollutants that MAY cause cancer). They recommend eating no more than 12 ounces
of fish/wk, and vary your choices (eg salmon, tuna, shellfish). The lead researcher of this
recent study of PCBs suggests eating no more than 8 ounces of farmed salmon per month.
Most canned salmon is wild, so alternating fresh salmon (likely farmed) with canned salmon
may make some sense. Remove the skin and the fat under the skin when having fresh salmon,
as this is where the PCBs accumulate; broil, bake, poach or grill the fish, as this will
also allow the fat (and PCBs) to drain off (plenty of omega-3 fatty acids will remain).
Here is the low-down of various fish (from Nutrition Action Health Letter, June 2004):
Here is another summary of various fish with estimated levels of EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid).
- Wild Salmon: Derived from ocean and rivers. Environmental impact: low.
Contamination level: low. Omega-3 fatty acid levels: Very high (about 3000 mg/6 oz cooked fish).
Costs about $15/pound
- Farmed Salmon: derived from ocean pens. Environmental impact: high
(pollutes the shoreline, carry flesh-eating sea lice to wild salmon).
Contamination level: high (PCBs, dioxin, pestacides). Omega-3 fatty acid levels:
very high (about 4500 mg/6 oz cooked fish). Costs about $6/pound
- Canned Salmon: Derived from wild salmon. Environmental impact: low.
Contamination level: low. Omega-3 fatty acid levels: very high (about 3000 mg/6 oz).
Costs about $2 to $8/pound
- Smoked salmon: Derived from farmed salmon. Environmental impact: high if derived from farmed salmon,
low if derived from wild salmon. Contamination: no data available. Omega-3 fatty acid levels: very high
(about 2700 mg/6 oz). Costs about $10-$40/pound
- Farmed Organic Salmon: Derived from ocean pens. Environmental impact: medium.
Contamination levels: no data available. Omega-3 fatty acid levels: no data available.
Costs about $12/pound
- Farmed Catfish: Derived from inland ponds. Envionmental impact: low.
Contamination level: low. Omega-3 fatty acid levels: medium (about 300 mg/6 oz cooked catfish).
Costs around $6/pound
- Farmed Trout: Derived from inland raceways that simulate flowing water.
Environmental impact: medium. Contamination level: low. Omega-3 fatty acid levels: high
(about 1300 mg/6 oz cook trout). Costs about $10/pound
|Fish||EPA plus DHA gram per 3 oz serving (edible portion)||Amount of fish (oz) required to provide about 1 gm of EPA plus DHA per day|
|Alaskan king crab||0.35||8.5|
|Halibut||0.40 to 1.0||3 to 7.5|
|Mackerel||0.34 to 1.57||2 to 8.5|
|Atlantic farmed salmon||1.1 to 1.8||1.5 to 2.5|
|Atlantic wild salmon||0.9 to 1.6||2 to 3.5|
|Sardines||1.0 to 1.7||2 to 3|
|Shrimp, mixed species||0.27||11|
|Fresh tuna||0.24 to 1.28||2.5 to 12|
|White tuna (canned in water, drained)||0.73||4|