mardi 30 décembre 2014

Fish and mercury

"I know eating farm-raised fish is not as healthy as eating wild-caught fish. But is eating farm-raised fish better than eating no fish at all? Also, how often is it advisable to eat farm-raised fish?

Thanks


Experts have raised concerns about farm raised fish, which in some cases are raised on unnatural diets and crammed into small enclosures that can breed disease, prompting aquaculture operators to rely heavily on antibiotics.
But farming practices are improving, and consumers have a number of healthy and eco-friendly farmed options, said Tim Fitzgerald, a scientist and sustainable seafood expert at the Environmental Defense Fund. He said some merchants set high standards for the farmed salmon and other fish they sell, including the supermarket chains Wegmans and Whole Foods and the producer Verlasso.
A few of the farmed varieties that are produced responsibly are also relatively high in omega 3 fatty acids, the polyunsaturated fats that promote cardiovascular health. They include arctic char, rainbow trout and oysters, he says.
Mr. Fitzgerald recommends eating a mix of farmed and wild seafood. “You paint yourself into a corner if you say you don’t want to eat any farmed fish ever,” he said. “It automatically removes 50 percent of the U.S. seafood supply from your choices.” Some good wild options are Alaskan salmon, Atlantic mackerel and sardines.
From a health perspective, farmed salmon is a good choice, said Roxanne Karimi, a research scientist at the School of Marine and Atmospheric Sciences at Stony Brook University. Dr. Karimi has found that both farmed and wild salmon are high in omega 3’s compared to shrimp, tuna and other fish, and they are generally very low in mercury, a particular concern for pregnant women and young children.
Dr. Karimi said that eating smaller types of fish is best. In her research, she has found that people who eat top predator fish like shark, swordfish and marlin have more mercury in their blood but not necessarily more omega 3’s and selenium — a nutrient that is abundant in fish — than people who eat seafood that is lower on the food chain, like sardines, shellfish, anchovies and herring."
http://well.blogs.nytimes.com/2014/12/18/ask-well-wild-fish-vs-farmed-fish/?rref=health&module=Ribbon&version=context&region=Header&action=click&contentCollection=Health&pgtype=Blogs
Wild caught fish tastes better.
Is it right? For salmon it is obvious and I tried several times the test in good conditions of reliability.

What about mercury?
By the way the levels of contaminants in wild Alaskan salmon are much lower than if they were from the lower 48 and the populations there are widely recognized as sustainably managed.


Omega3 PUFA?
Roxanne Karimi, research scientist at Stony Brook University, correctly states that from a health perspective, farmed salmon is a good choice. In fact, all salmon - both farmed and wild - contain similar amounts of omega 3 fatty acids.
http://health.clevelandclinic.org/2014/03/fish-faceoff-wild-salmon-vs-farmed-salmon/
http://www.stateofthesalmon.org/hatcheries/

Salmon 
Species
Total Fat 
(Grams per 3 ounce cooked portion)
Omega-3 Fatty Acids (Milligrams per 3 ounce cooked portion)Cholesterol 
(Milligrams per 3 ounce cooked portion)
Atlantic, 
Farmed
10.51,80054
King, 
Wild
11.31,70072
Coho, 
Wild
3.790047
Sockeye, 
Wild
5.780054
Chum, 
Wild
4.180081
Pink, 
Wild
4.570055


http://seafoodhealthfacts.org/seafood_choices/salmon.php
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Nutritional content

There are some key nutritional differences between wild and farmed salmon, according to USDA data. A small fillet of wild salmon has 131 fewer calories and half the fat content of the same amount of farmed salmon. And although farmed salmon may have slightly more omega-3 fatty acids, it also has 20.5 percent more saturated fat content — and that’s fat you do not want."

Are there color additives in farmed salmon?
Yes

"Does the salmon have color additives?

Wild salmon get their pink or reddish flesh color through their diet of krill, plankton, and other small organisms. These organisms contain astaxanthin, which is a natural antioxidant in the same family as the beta-carotene found in carrots. Astaxanthin and beta-carotene are classified as carotenes, which are a subclass of carotenoids, and are the pigments responsible for the red, orange, and yellow colors found in foods and nature. Similarly to wild-caught salmon, farm-raised salmon are provided color through their diets by ingesting these same carotenes, primarily astaxanthin and a similar compound canthaxanthin. These compounds, which are added to salmon feed, are approved by the U.S. Food and Drug Administration (FDA) for use as color additives in food. Currently, most of the astaxanthin and canthaxanthin used in salmon feed is synthetic, although research is being done to improve the process of natural synthesis using microorganisms.
Salmon and trout have the unique ability to retain carotenes in their flesh. A white flesh fish species, such as catfish, does not have this ability and it is not necessary to include these compounds in the diet of farm-raised catfish. In order for farm-raised salmon and trout to be acceptable to consumers, their color must be similar to the wild-caught fish consumers are familiar with. Recently, it is required to label farm-raised salmon as ‘color added’ because of the addition of carotenes in their feed, seafood companies do not add dyes directly to the flesh of the fish."


Health effects of Omega 3 PUFA from fish
http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD003177.pub2/abstract

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