Most Americans are deficient in vitamin Dor close to itand need to get much more from pills or foods. As it happens, fatty fish are the richest food sources by far, with tuna, sardines, mackerel, and salmon leading the pack. 
But not all salmon are good sources of vitamin D… with farmed salmon lagging far behind their wild cousins. 
Three years ago, we reported that Boston University tests found much more vitamin D in wild salmon than in farmed salmon (Lu Z 2007).
Fish fit the vitamin D bill; Sockeye salmon stand out
In addition to getting vitamin D from supplements, certain fish rank among the very few substantial food sources of vitamin D, far outranking milk and other D-fortified foods.

Among fish, wild Sockeye Salmon may be the richest source of all, with a single 3.5 ounce serving surpassing the US RDA of 400 IU by about 70 percent:

Vitamin D per 3.5 ounce serving*

Sockeye Salmon  687 IU
Albacore Tuna  544 IU
Silver Salmon  430 IU
King Salmon  236 IU
Sardines  222 IU
Sablefish  169 IU
Halibut  162 IU

*Independent lab tests commissioned by Vital Choice.
Critically, the BU researchers found that a 3.5 oz sample of wild Pacific salmon had four times more vitamin D (988 IU), compared with farmed Atlantic salmon (245 IU).
The amount found in wild salmon was 64% higher than the US RDA (600 IU) from birth through age 51 ... which many researchers want raised to at least 1000 IUs per day.   
For more on that 2007 BU study, see "Wild Salmon Affirmed as Top Vitamin D Source.”   
Now, the results of tests commissioned by Canada's CTV News affirm those findings... and then some.   
Canadian TV station finds wild salmon far higher in vitamin D 
When CTV sent samples of both to be tested, the results showed that wild Pacific salmon had eight times more vitamin D than farmed Atlantic salmon.   
(Most farmed salmon is of the Atlantic species, which was nearly exterminated by damming of rivers in America, and by lice and other pressures from poorly sited and designed Norwegian and Scottish ocean-pen salmon farms.)    
Specifically, the samples of wild Pacific salmon had more than 500 IU of vitamin D per 3.5 oz serving, while farmed salmon had only 60 IU. And, the farmed salmon had three times as much fat as the wild salmon (13 percent fat, versus only 2.5 percent). 
Because fat has more than twice as many calories as protein or carbohydrates, this means that farmed salmon also has more calories than wild salmon.   
Their higher fat content explains why most tests find that most farmed salmon have slightly more omega 3 fatty acids than most (not all) wild salmon… though the difference is minor.   
Unfortunately, the CTV report failed to mention that, compared with wild salmon, farmed salmon is much higher in omega-6 fats, which compete with omega-3s in our bodies for absorption into cell membranes, and tend to promote inflammation.
That excess of omega-6 fatty acids can have undesirable consequences, as Norwegian scientists found when they fed farmed salmon to volunteers… see "Farmed Salmon's Diet Yields Unhealthful Cardiovascular Effects.
    • CTV News. Farmed vs. wild salmon – which is better? March 5, 2010. Accessed at bc_ctv_investigates_food_fish_100219/201
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