Farmed Seafood: What’s Safe and Nutritious
Mark’s Daily Apple
by Mark Sisson: The
Scattered Mind: Finding Focus in a World of Distractions
types of aquaculture setups is interesting and useful, but we're
ultimately interested in whether they can produce safe, nutritious,
affordable seafood. Wild seafood can be pricey, unavailable, and
of questionable merit or sustainability. Certain wild species are
definitely worth pursuing – Alaskan salmon, sardines, herring, mackerel,
to name a few – but there are environmental (overfishing, collateral
damage to other important species, structural damage to the marine
environment) and health (accumulation of heavy metals like lead
and mercury, polychlorinated biphenyl/PCB, dioxin) issues that the
conscious fish eater must stay abreast of. Healthy and safe farmed
seafood, then, would be a welcome alternative, if it's out there.
get down to it.
seafood is safe to eat? Is there anything like grass-fed beef or
pastured chicken available in scales or shells?
As a whole,
farmed shellfish, when compared to wild shellfish, are very good
bets for the simple fact that both lead very similar lives. Every
whether farmed or wild, spends its life in the ocean attached to
something – rocks, a rope, a pillar, coral, the ocean floor. The
only difference is that farmed shellfish are deliberately placed
there by farmers, while wild shellfish are distributed by the hand
of Poseidon (actually, the Nereids
do all the work while he gets the credit, but such is the life of
a sea nymph). Most importantly, they all use the same sea water.
They all obtain their food by sifting through that same sea water.
Farmers don't have to provide food. They're not scattering corn
across the water, because it would be a waste. Shellfish, you see,
are filter feeders.
me to the primary concern people have with shellfish, or mollusks.
"Filter feeder" just sounds bad. When we hear the phrase, we think
of physical filters, the type we use in everyday life, like an air
filter in a car engine or a coffee filter. Physical filters accumulate
the undesirable stuff and are either cleaned, tossed, or recycled.
They certainly aren't eaten. Well, shellfish aren't physical filters.
They process toxins. They render harmful compounds inert and expel
them. It's true that if they reside in waters rich in heavy metals
and industrial contaminants (like PCB or dioxins), some of those
metals and contaminants will show up in the meat, but that's true
for any sea creature. In fact, shellfish are some of the safest,
least contaminated farmed seafood whenever
extremely nutritious. Shellfish are extremely rich in vitamins and
minerals. Three measly ounces of raw Pacific oyster (the bulk of
which are farmed) gets you over 100% of the RDA for zinc, copper,
selenium, B12, and half of the RDA for iron. For every 1.5 g of
they provide, just 0.1 g of omega-6
comes along for the ride. Bay scallops
are high in magnesium and selenium, clams are good for iron, copper,
and selenium, abalone for selenium and magnesium,
while the lowly sea snail gives massive amounts of magnesium (200
g of snail gives over 500 mg of magnesium; maybe they're counting
the shell?) and good amounts of selenium.
Lately, a favorite
of mine has been the green-lipped mussel, shipped frozen from New
Zealand. I initially got interested in this particular variety because
of the research into green-lipped mussel extract as a canine
arthritis treatment. Buddha isn't arthritic, but I find this
stuff fascinating. I've had some arthritis
in the past, and it never hurts to cover all your bases ahead of
time. Besides, mussels are delicious and nutritious. The NZ green-lipped
mussel gets good marks from the Monterey
Bay Aquarium Seafood Watch, owing to its farmers' sustainable
practices: attach young mussels to ropes, lower the ropes into the
ocean, and let nature take its course. I was also surprised to see
the amount of omega-3s in these things. According
to one study, 100 g of them (flesh only, no shells, frozen)
comes with 1.5 g of DHA, 1.26 g of EPA, and not even half a gram
of omega-6 fats.
are safe and just as nutritious as wild. If you're worried about
contamination, check the source and do some research. Always buy
still living shellfish (dedicated seafood markets or Asian grocers
are great places to buy live shellfish) where you can. If frozen
is available, check the label and avoid imports from China, where
are more likely to be heavily polluted.
catfish is a bottom feeder, which sounds bad but doesn't have to
be. They're just rapacious eaters, or foodies, even – a bit like
hogs. If you feed them garbage and raise them in polluted waters
(like occurs in Chinese catfish farms – check your labels!), you
can't really blame the species.
is far fattier than wild catfish while being lower in omega-3s,
but catfish has never been prized for its omega-3 content. While
farmed catfish does have more omega-6 than wild – about 1.5g for
every 100 g fillet, compared to around 0.22 g – most of the "added"
fat in farmed is monounsaturated (5.7 g/100 g) and saturated (2.5
g/100 g) (PDF).
Not too bad, especially if you compare it to something like conventional
skin-on chicken thigh, which gives you 4 g saturated
fat, 6 g monounsaturated fat, and 3 g omega-6s for a 100 g serving.
US catfish farmers may not be feeding their fish pristine, natural
diets of bottom-dwelling crustaceans, insects, and small fish, instead
opting for combinations of meat and bonemeal, bloodmeal, fishmeal,
various seedmeals, corn, soy, wheat
byproducts, and vitamin/mineral supplements, but catfish seem to
turn out decent fatty-acid profiles despite the departure from ancestral
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May 14, 2011
© 2011 Mark's Daily Apple
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