Posted by Larry Hoover on October 31, 2004, at 11:17:14
In reply to Re: Fish oil » Larry Hoover, posted by JLx on October 31, 2004, at 10:12:02
> > > I actually like fish a lot and could it 4-5 times a week (especially smoked salmon) but I worry about the mercury as I already have mercury amalgams. I was eating farm raised salmon until I read about it. Did you know that they have to dye it pink, otherwise it's gray? Because they don't eat what wild salmon eat. For that reason they also have less Omega-3. It's very frustrating that we CAN'T eat a lot of fish without all these pollution worries.
>
> > According to the USDA database, farmed Atlantic salmon has more omega-3 fatty acids than does wild caught.
>
> This is a copy of a NYT article that I read last year: http://www.fass.org/fasstrack/news_item.asp?news_id=1264
>
> "While all salmon in the store may look similar, the Department of Agriculture says farmed salmon contains almost twice the total fat, more than twice the saturated fat and fewer beneficial omega-3 fatty acids than wild salmon."I'm happy to discuss this further. I don't want to be right. I want to be correct. You ask good questions.
The link that I have always used, which led to direct comparisons of specific fatty acid concentrations, showed ~40% more EPA/DHA in farmed Atlantic salmon than wild-caught. That link no longer works, and the new USDA database (recently updated, but less informative) does not provide me with the same detail.
I checked for an archive of that site, and it's available..... <pheww!>
http://web.archive.org/web/20040202200808/http://www.cs.princeton.edu/~ah/food/
If you check under lipids, EPA and DHA are found in different tables, as 20:5 and 22:6 respectively. You'll see that farmed Atlantic salmon has more of these fatty acids than does wild caught.
http://web.archive.org/web/20040228111536/www.cs.princeton.edu/~ah/food/data/fishshellfish.lipids2
http://web.archive.org/web/20040305113516/www.cs.princeton.edu/~ah/food/data/fishshellfish.lipids3
I don't know the date of these findings, but that is what I relied on for my comment.
> "farmed salmon are not naturally salmon pink or red, and that if they were not fed artificial colors they would range from gray or khaki to pale yellow or pale pink. Wild salmon turn pink from the krill and shrimp they eat. (Farmed salmon eat a fishmeal diet.)"
The two pigments in question, canthaxanthin and astaxanthin, are natural forms of beta-carotene. Yes, it has been possible to supply synthetic versions of these, but they are chemically identical to the forms found in e.g. shrimp or flamingoes, or the natural foods consumed by salmon in the wild.
http://www.chemistry.org/portal/a/c/s/1/feature_ent.html?DOC=enthusiasts%5Cent_pinkchem.html
Too much of certain forms of carotenoids are toxic (consider Retin-A for acne, which is teratogenic). Wild fish have these exact same pigments. It is disingenuous to call farmed fish "dyed". It is deceptive to raise the concern only for farmed fish, with regulated beta-carotene supplement levels. What are the levels in wild-caught fish?
> This was the study I had read about recently http://www.aftenposten.no/english/local/article861693.ece and it made sense to me as it's similar to the difference between grain or grass fed beef.
Quite correct. However, grain-based salmon rations are a European phenomenon. North and South American feeds do not contain appreciable amounts of grain. Hmmmm. Okay, my data may be older. I can say they didn't contain appreciable grain, a decade ago. Economic factors may be shifting towards other food sources than a primarily fish meal pellet.
>
> http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2296923&dopt=Abstract
>
> That's a very tiny sample.Again, that is European data.
> Can we trust the USDA on this one?
I trust the USDA data, but I also recognize that it may not represent all samples. They only test a tiny fraction of available foods.
> > Farmed fish is attracting far more adverse publicity than it deserves, IMHO, at least from a nutritional or contaminant standpoint. Pollutant levels in virtually all fish are falling with time (excluding those caught near polluting industries), both in wild caught and farmed fish. The health studies that have shown that fish eaters were healthier than those who ate none were conducted on people who ate more heavily polluted fish than that which is available today. All food is contaminated. The reason fish has attracted this attention is a political act.
> >
> > Here are a couple of links to things I wrote.
> >
> > Lar
> >
> > http://www.google.ca/groups?hl=en&lr=&selm=qo5Mb.119%24k97.33817%40news20.bellglobal.com
> >
> > http://www.google.ca/groups?hl=en&lr=&selm=fXRIc.11766%24RD4.875328%40news20.bellglobal.com
>
> Thanks for the links. I don't worry so much about carcinogens, hoping the best for my immune system there, as mercury specifically, as I already have enough of that stuff, but apparently mercury doesn't accumulate in the flesh of salmon, so that's good.Mercury does accumulate in salmon. It does move up the food chain. The solution, though, is selenium intake.
Sci Total Environ 2000 Jan 17;245(1-3):15-24
An assessment of selenium to mercury in Greenland marine animals.
Dietz R, Riget F, Born EW.
National Environmental Research Institute, Department of Arctic Environment, Copenhagen, Denmark. rdi@dmu.dk
Information on mercury and selenium molar relation in muscle, liver and kidney tissue of Greenland marine animals is presented. In the majority of the samples selenium was present in a molar surplus to mercury. This was most clear in molluscs, crustaceans, fish and seabirds. A 1:1 molar ratio was found in tissues of marine mammals with high mercury concentrations (above approx. 10 nmol/g). This was most clearly demonstrated for liver and kidney tissue of polar bear and for ringed seal with high mercury concentration in the liver. These findings support previous results found in liver tissue of marine mammals, suggesting that methyl mercury is detoxified by a chemical mechanism involving selenium. If the anthropogenic release of mercury to the environment increases in the future due to increasing energy demands, species such as polar bears and seals with high tissue mercury concentrations should be monitored to elucidate whether this protective mechanism can be maintained in target organs.
> I like salmon a lot. Please convince me, Larry, that the farm raised variety is a good thing. :)
>
> JLI eat it, and without qualms. I am convinced that the health benefits far far outweigh the risks (provided, of course, the fish is cultured with consideration for the environment).
I'm happy to address all of your concerns, to the best of my ability.
Lar
poster:Larry Hoover
thread:398076
URL: http://www.dr-bob.org/babble/alter/20041022/msgs/409550.html