How Much Vitamin D in Salmon: Wild vs. Farmed

Wild salmon typically delivers several times more vitamin D than farmed salmon, though the exact amount depends on the species, where it was caught, and what the farmed fish were fed. Research measuring vitamin D3 in fillets has found that farmed Atlantic salmon contains roughly a quarter of the vitamin D found in wild-caught Atlantic salmon, a gap wide enough to meaningfully change how much of the nutrient you get from a single serving.¹ The reasons behind this difference are more interesting than you might expect, involving everything from the ocean food web to a surprising discovery about fish making their own vitamin D from sunlight.

What the Numbers Actually Look Like

A detailed study of Atlantic salmon from different sources found that wild fish caught in the Baltic Sea averaged about 18.5 micrograms of vitamin D3 per 100 grams of fillet, while wild salmon from the North Sea came in around 9.4 micrograms per 100 grams.² Farmed Atlantic salmon in that same study ranged from about 3 to 9.5 micrograms per 100 grams, with more recent data from 2018 showing a range of roughly 2.3 to 7.3 micrograms per 100 grams.²

To put those numbers in perspective, adults generally need about 15 micrograms (600 IU) of vitamin D per day, and people over 70 need 20 micrograms (800 IU). A 100-gram portion of wild Baltic Sea salmon could supply your entire daily requirement and then some. The same portion of farmed salmon might provide anywhere from about a sixth to half your daily needs, depending on the batch. That is a meaningful difference if salmon is one of your primary vitamin D sources.

The variation within each category matters just as much as the gap between them. Wild salmon vitamin D levels can swing dramatically depending on where the fish lived and what it ate. Even farmed salmon from different producers can differ by a factor of three or four. This makes broad generalizations tricky, and it is one reason nutritional databases often list a single number for “salmon” that may not match what ends up on your plate.¹

Why Wild Salmon Has So Much More

Fish accumulate vitamin D primarily by storing it in their liver, fat tissue, and the fat woven through their muscle.³ Wild salmon get their vitamin D from two main sources, and both are difficult to replicate in a farm setting.

The first source is diet. Wild salmon eat zooplankton, krill, and smaller fish, all of which contain vitamin D. That vitamin D concentrates as it moves up the food chain. A small krill might have a modest amount, but a salmon that eats thousands of krill over its lifetime accumulates vitamin D in its tissues. The richer and more varied the prey base, the more vitamin D ends up in the fillet. This helps explain why Baltic Sea wild salmon had nearly twice the vitamin D of wild North Sea salmon in the study mentioned above: different waters, different prey availability, different fat content in the fish.²

The second source is sunlight, and this is the more surprising part. Until fairly recently, the prevailing view in fish biology was that fish got essentially all of their vitamin D from food, not from UV exposure. Mammals produce vitamin D3 in their skin when UV-B light hits a precursor molecule called 7-dehydrocholesterol, and researchers assumed that fish skin worked differently or that underwater UV levels were too low to matter. Recent field trials have upended that assumption.

The Sunlight Discovery

A study comparing Atlantic salmon raised outdoors with fish raised indoors found striking results. Both groups received identical commercial feed, yet the outdoor group ended up with five times the whole-body vitamin D content of the indoor group.⁴ The only plausible explanation was that the fish exposed to natural sunlight were synthesizing vitamin D in their skin, just as humans and other mammals do.

Experimental work has confirmed that UV-B light specifically triggers the same chemical conversion in Atlantic salmon skin, converting 7-dehydrocholesterol into pre-vitamin D3.⁵ Although earlier research had dismissed this pathway as irrelevant for fish under natural conditions, the new findings suggest UV-B could actually be a dominant source of vitamin D3 in salmon exposed to sunlight.⁵

This has real implications for the wild-versus-farmed gap. Wild salmon spend time near the ocean surface where they encounter UV-B light. Most farmed salmon, by contrast, live in pens with varying amounts of surface exposure, and land-based farms are typically indoors with no UV exposure at all. Land-based farmed salmon in particular tend to have lower vitamin D3 accumulation in their muscle compared to wild fish.⁶ The combination of a restricted diet and minimal UV exposure creates a double disadvantage.

What Farmed Salmon Eat and Why It Matters

Farmed salmon feed has shifted substantially over the past two decades. Aquaculture has moved toward more plant-based ingredients, replacing some of the fishmeal and fish oil that historically made up most of the diet.⁷ This shift was driven by sustainability concerns and economics. Wild fish stocks used for fishmeal are limited, and plant proteins like soy and canola meal are cheaper and more readily available. The trade-off is that plant ingredients carry little to no vitamin D3, so the farmed fish end up with less of the nutrient in their tissues unless the feed is specifically supplemented.

Feed manufacturers do add vitamin D3 to salmon feed, and it is a regulated part of commercial feed formulation. But monitoring over a 15-year span from 2006 to 2021 found no clear upward trend in vitamin D concentrations in farmed Atlantic salmon fillets, with median concentrations sitting around 7.6 micrograms per 100 grams.⁸ In other words, the industry has been maintaining vitamin D at a fairly flat level rather than actively boosting it. Current commercial feed inclusion rates of vitamin D3 can result in lower vitamin D accumulation in muscle than what wild salmon achieve through their natural diet and sun exposure.⁶

Can Fortified Feed Close the Gap?

The encouraging news is that higher-dose vitamin D supplementation in feed does work. Research on Atlantic salmon given elevated dietary vitamin D3 during winter months showed that supplementation significantly increased vitamin D3 concentrations in plasma, liver, and muscle, with no adverse health effects in the fish.⁹ The elevated feed levels were able to mimic the tissue concentrations that naturally occur during summer, when the fish would otherwise get a vitamin D boost from longer daylight hours and greater UV exposure. This suggests that if the aquaculture industry chose to increase vitamin D3 levels in feed, the fillets reaching consumers could contain more of the nutrient.

Whether this becomes standard practice is a question of industry incentives and regulation. Feed costs, regulatory limits on vitamin supplementation in aquaculture, and consumer demand all play a role. For now, most commercially available farmed salmon still sits at the lower end of the vitamin D spectrum compared to wild-caught fish.

Variation You Should Expect

One of the most underappreciated aspects of vitamin D in salmon is how much the numbers bounce around, even within the same category. Wild sockeye salmon, wild coho, wild pink salmon, and wild Atlantic salmon all have different fat contents and different diets, which means different vitamin D levels. Pacific species in general tend to have high vitamin D, and traditionally processed wild salmon can have even more. Surveys of traditional native Alaskan foods found that smoked and dried salmon contained over 10 micrograms of vitamin D3 per 100 grams, and some also contained meaningful amounts of 25-hydroxyvitamin D3, a form that is already partially activated and may be more potent per microgram than regular vitamin D3.¹⁰

Season matters too. Wild salmon caught later in their feeding season tend to be fattier, and since vitamin D is fat-soluble and stored in fat and muscle, fattier fish typically contain more of the nutrient. The same logic applies to farmed salmon raised in seasonal outdoor pens versus year-round indoor tanks.

Cooking method also affects retention. Earlier research evaluating vitamin D content in several fish species assessed the effects of baking and frying and found that vitamin D content varied, though the overall message is that common cooking methods do not destroy most of the vitamin D in fish.¹ You do not need to eat raw salmon to benefit from its vitamin D content.

Outdated Nutrition Tables

If you have looked up vitamin D in salmon using the USDA FoodData Central database or a nutrition app, you may have seen a single generic entry for “salmon, Atlantic, farmed, cooked” or something similar. Researchers have pointed out that many of these reference values are outdated and do not reflect the changes in aquaculture feed composition over the past two decades, nor do they account for the wide variation between producers and regions.¹ A nutrition label telling you that a serving of salmon provides some fixed percentage of your daily vitamin D might be based on older analyses that do not match modern farmed fish.

The shift toward plant-based feed ingredients in farmed salmon has changed the nutritional profile of the fillets, and not just for vitamin D.⁷ Unless databases are regularly updated with new analytical data from current farmed salmon products, the numbers consumers rely on may overstate the vitamin D they are actually getting.

The Bigger Nutritional Picture

Vitamin D is one piece of the nutritional comparison between wild and farmed salmon, and the story is not as simple as “wild is better in every way.” Farmed Atlantic salmon tends to have significantly higher total fat content than wild, mostly from saturated and monounsaturated fatty acids, along with higher levels of omega-6 fatty acids. Wild salmon, on the other hand, has a more favorable omega-3 to omega-6 ratio and higher concentrations of the marine omega-3 fatty acid DHA.¹¹ Both farmed and wild salmon still provide substantial amounts of EPA and DHA, though. A 200-gram serving of either type per week provides well above what European food safety authorities consider an adequate weekly intake of these omega-3 fats.¹¹

On the contaminant side, wild salmon actually tends to carry higher levels of certain persistent organic pollutants, dioxins, PCBs, and mercury than farmed salmon, though concentrations in both types fall well below safety limits set by regulatory agencies.¹¹ A Canadian analysis reached a similar conclusion, finding that contaminant levels in farmed salmon sold in Quebec markets were low enough to allow regular consumption without exceeding tolerable daily intakes.¹² Wild salmon also tends to have higher levels of essential trace elements like selenium, copper, zinc, and iron.¹¹

So wild salmon wins on vitamin D, omega-3 ratios, and trace minerals. Farmed salmon wins on lower contaminant levels and price. Both are safe to eat regularly, and both provide meaningful omega-3 fatty acids. If vitamin D is your main concern, wild salmon is the clear choice. If your priority is affordable fish that is safe and still nutritious, farmed salmon is a reasonable option, just one that delivers less vitamin D per serving.

What Land-Based Farming Means for the Future

The aquaculture industry is increasingly moving toward recirculating aquaculture systems, essentially large indoor tanks on land, as an alternative to open-water sea pens. These systems offer advantages in biosecurity and environmental impact, since they avoid the parasite and waste issues that plague traditional salmon farms. But for vitamin D content, the move indoors is a step in the wrong direction. Without any exposure to natural UV-B light, land-based farmed salmon depend entirely on feed supplementation for their vitamin D, and current commercial feed levels produce lower muscle vitamin D than what wild salmon accumulate.⁶

Some researchers have proposed incorporating UV-B lamps into indoor aquaculture systems, essentially giving the fish artificial sunlight to stimulate their own vitamin D production. The science supports the concept: UV-B exposure does trigger the same skin chemistry in salmon as in humans.⁵ Combined with elevated feed supplementation, which has already been shown to safely increase tissue vitamin D3 concentrations in farmed salmon without health consequences for the fish, these approaches could narrow the wild-farmed gap significantly.⁹ Whether the economics of UV lamps in massive indoor tanks pencil out for producers remains an open question. But the biological tools to produce vitamin D-rich farmed salmon exist. The challenge is adoption.

1
PubMed Central. An evaluation of the vitamin D3 content in fish: Is the vitamin D content adequate to satisfy the dietary requirement for vitamin D?
2
PubMed Central. Vitamin D in Wild and Farmed Atlantic Salmon (Salmo Salar)-What Do We Know?
3
Aquaculture Nutrition. The significance of vitamin D for fish: a review
4
PubMed Central. Field Evidence of Endogenous Vitamin D Synthesis in Atlantic Salmon Induced by Natural Sunlight
5
Aquaculture. UV-B light stimulates the production of Vitamin D3 in Atlantic salmon
6
PubMed Central. Balancing Dietary Vitamin D3 and Phosphorus Improved Growth, Mineralization, and Fecal Characteristics of Atlantic Salmon Post-Smolts in Land-Based Aquaculture
7
PubMed. Temporal variations in the nutrient content of Norwegian farmed Atlantic salmon, 2005-2020
8
Journal of Agriculture and Food Research. Nutrients and contaminants in farmed Atlantic salmon fillet and fish feed from 2006 to 2021
9
PubMed Central. Elevated Dietary Vitamin D Supplementation During Winter can Mimic Vitamin D Levels Induced by Summer Daylight Exposure in Atlantic Salmon
10
Journal of Food Composition and Analysis. Survey of vitamin D and 25-hydroxyvitamin D in traditional native Alaskan meats, fish, and oils
11
PubMed. Lower levels of Persistent Organic Pollutants, metals and the marine omega 3-fatty acid DHA in farmed compared to wild Atlantic salmon
12
PubMed. Risk and benefits from consuming salmon and trout: a Canadian perspective