Salmon Nutrition: EPA, DHA, and the Farmed vs Wild Question

Most people asking about farmed vs wild salmon expect the answer to be “wild is better.” The actual answer is more complicated. Depending on the species and the farm, modern farmed Atlantic salmon matches or beats wild salmon on the thing most people care about: EPA and DHA content.

The “farmed is bad” claim had some basis in fact, maybe 15 years ago. It doesn’t hold up anymore. This is one of the cleaner cases in nutrition where the evidence has shifted and the conventional wisdom hasn’t caught up.

The health benefits of salmon mostly come down to two things: those marine omega-3s, and a vitamin D content that almost nobody talks about enough.

Nutritional Profile

Per 100g of cooked farmed Atlantic salmon (USDA FoodData Central):

Two numbers stand out immediately: 2.3g of EPA+DHA in a single 100g serving, and 62% of the daily value for vitamin D. Most people aren’t eating much else that provides either of those in meaningful amounts.

EPA and DHA: Why Marine Omega-3s Are Different

There are three main dietary omega-3 fatty acids. ALA (alpha-linolenic acid) comes from plant sources like flaxseed, walnuts, and chia seeds. EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) come primarily from marine sources.

The distinction matters because your body doesn’t treat them the same way. ALA is a short-chain omega-3. To use it the way it uses EPA and DHA, your body has to convert it through a multi-step enzymatic process. That conversion is inefficient. Research estimates that humans convert less than 10% of dietary ALA to EPA, and conversion to DHA is even lower, often under 1% (Burdge and Calder, 2005, Proceedings of the Nutrition Society). You can eat a lot of flaxseed and still have low tissue DHA levels.

EPA and DHA from salmon don’t need that conversion step. They’re already the forms your body uses directly. Think of it like the difference between receiving a piece of furniture as a flat-pack kit versus having it delivered fully assembled. The end product is the same molecule, but with ALA, most people are losing the majority of what they started with along the way.

EPA is primarily anti-inflammatory. It’s involved in eicosanoid signaling, producing compounds that modulate the inflammatory response. DHA is structural. It’s a key component of brain cell membranes, retinal photoreceptors, and the membranes of virtually every cell in your body. DHA is particularly concentrated in the brain. It’s especially important during fetal development and early childhood, when neural tissue is growing rapidly.

Neither of these roles is well-served by ALA. This is why marine sources matter specifically, and it’s why salmon’s 2.3g of EPA+DHA per 100g is a meaningfully different number from the omega-3 content of a handful of walnuts. For more on how the omega-3/omega-6 balance works at the cellular level, see omega-3 and omega-6 in the diet.

Farmed vs Wild: What the Data Actually Shows

Wild Pacific salmon comes in several species with real nutritional differences. King (Chinook) salmon is the fattiest, with roughly 12g total fat per 100g and high EPA+DHA. Sockeye and coho are in the middle range. Pink salmon is the leanest, with about 3.5g total fat per 100g and lower absolute EPA+DHA, though it’s also lower in calories.

Atlantic salmon (what you see labeled “Atlantic salmon” in grocery stores) is almost entirely farmed. Wild Atlantic salmon populations are commercially depleted in most regions.

Early farmed salmon, from roughly the 1990s through early 2000s, was fed high-fishmeal and fish-oil diets. Those diets produced fish with excellent EPA+DHA but created sustainability pressure on small forage fish. Farms shifted toward plant-based and algae-based feed over the following decade (Sprague et al., 2016, Aquaculture, PMID: 27840571). Critics predicted omega-3 content would fall. The shift to algae-based feed largely prevented that because algae is where EPA and DHA originate in the marine food chain anyway. Wild salmon get their omega-3s by eating krill and small fish that ate algae. Farmed salmon fed algae directly skips the middlemen.

Modern farmed Atlantic salmon delivers around 2.3g EPA+DHA per 100g. That puts it in the same range as sockeye and coho, and above pink salmon. King salmon still edges it out by fat content, but farmed Atlantic isn’t the omega-3-depleted product that early critics of aquaculture were concerned about.

On contaminants: PCBs in farmed salmon were a real concern in older data. Current monitoring across multiple regulatory frameworks (EU, FDA, EFSA) shows farmed salmon well within acceptable limits. Mercury in all salmon species is consistently low. The FDA’s testing data shows salmon averaging 0.022 ppm, against a limit of 1 ppm. This isn’t a mercury fish. Tuna, swordfish, king mackerel, and shark are the species where pregnant women and children need to be careful. Salmon doesn’t belong in that category.

Vitamin D, B12, and Astaxanthin

The vitamin D content in salmon is underappreciated. At 12.5mcg (500 IU) per 100g, it’s one of the few significant natural food sources of vitamin D3, the same form your skin synthesizes from sunlight and the form with better bioavailability than the D2 found in most fortified plant foods.

Vitamin D deficiency is common worldwide, and very few foods contain meaningful amounts naturally. The main sources are sunlight, fatty fish, and egg yolks. Fortified foods add D2 or D3 at modest levels. Salmon at two servings per week contributes roughly 1000 IU per week from food alone, which is a real contribution to vitamin D status. For the full mechanism of how vitamin D is processed once it enters your body, see vitamin D metabolism.

Vitamin B12 is straightforward. At 3.2mcg per 100g (133% of the daily value), salmon is an excellent source. This matters particularly for people who eat fish but limit red meat and poultry. B12 is found almost exclusively in animal products. Salmon covers the requirement in a single serving. See vitamin B12 science for why absorption is more complicated than intake numbers suggest.

Astaxanthin is the carotenoid pigment that gives salmon its characteristic orange-pink color. Wild salmon get it from krill and shrimp in their diet. Farmed salmon receive synthetic astaxanthin in their feed, which is chemically identical to what wild salmon produce from natural dietary sources. Astaxanthin is a potent antioxidant, roughly 10 times more potent than beta-carotene in some antioxidant assays. Early research links it to eye health, skin protection from UV, and anti-inflammatory effects, but most of the human evidence is preliminary. It’s a real compound with real antioxidant activity. The clinical evidence for specific health outcomes is still developing.

Mercury, Cooking, and Frequency

The mercury picture for salmon is simple. It’s a short-lived fish, low in the marine food chain, which means mercury doesn’t accumulate much. The FDA’s commercial fish testing data consistently puts salmon below 0.05 ppm, well under any meaningful threshold. There’s no consumption frequency concern for healthy adults, pregnant women, or children based on mercury. This is worth stating clearly because salmon gets lumped in with high-mercury seafood in some popular media, and that’s not accurate.

The cardiovascular case for fatty fish is strong. The AHA recommendation of two servings per week is based on multiple large cohort studies associating regular fatty fish consumption with lower cardiovascular disease mortality. The GISSI-Prevenzione trial (1999, Lancet, PMID: 10465168) gave omega-3 supplements to 11,324 patients who had recently survived a heart attack. The omega-3 group had 20% lower all-cause mortality at 3.5 years of follow-up. That trial was in a post-MI population, not a primary prevention context, so it doesn’t directly translate to “salmon prevents heart attacks in healthy people.” But it confirms that the mechanism is real. The inflammation and diet page covers the eicosanoid signaling pathway that EPA specifically affects.

On cooking: EPA and DHA are polyunsaturated fats, which means they’re more susceptible to oxidation at high heat than saturated or monounsaturated fats. At typical home cooking temperatures, the difference between methods isn’t large enough to override everything else. But if you’re poaching, baking at 375°F (190°C), or using sous vide at around 130°F (54°C), you’re preserving more of the omega-3s than you would pan frying at very high heat until well done. The bigger enemy of omega-3 content is overcooking time, not cooking method. Salmon cooked to 125-130°F internal temp is both safer than most people assume and better for preserving what makes salmon worth eating.

Two servings a week. Moderate heat. That’s the full practical summary.

This page is for general nutrition education. It’s not medical advice. Talk to your doctor or registered dietitian about dietary changes that affect your health.