Wild and farmed salmon are excellent sources of important nutrients like omega-3 fatty acids; differences between the two result from the environment they’re raised in and the food they eat.
The health benefits of eating salmon have made headlines in the last while, and people are listening. Consumer demand has grown, resulting in the amount of farmed salmon raised in the last two decades jumping from 27,000 metric tons to more than a million. (1)
Global wild salmon stocks have been depleted by half in the last few decades. (2)
With more pollutants in oceans, rivers and lakes than ever before, it’s reasonable to question which is safer and more nutritious to consume: wild salmon or farmed salmon.
Nutritional Differences Between Wild and Farmed Salmon
Farmed salmon are fed processed food high in fat to produce bigger fish in the shortest possible amount of time. Wild salmon eat whatever they find in their environment, and are smaller when harvested than farmed salmon. (3)
Calories 281 412
Protein 39 g 40 g
Fats 13 g 27 g
Saturated fats 1.9 g 6 g
Omega-3 3.4 g 4.2 g
Omega-6 344 mg 1944 mg
Cholesterol 109 109
Calcium 2.4% 1.8%
Iron 9% 4%
Magnesium 14% 13%
Phosphorus 40% 48%
Potassium 28% 21%
Sodium 3.6% 4.9%
Zinc 9% 5%
Vitamin C 0 13%
Farmed salmon is higher in fat, and this accounts for most of the added calories. It also contains slightly more omega-3 fats and much more omega-6 fats.
The diet farmed fish are fed is high in omega-6 fats, which contributes to fast weight gain, readying the fish for market much more quickly.
Wild salmon meat doesn’t contain any vitamin C; this is present in the farmed variety because it is added to their diet.
The “good” fats found in salmon, both wild and farmed, are among the main reasons salmon is recommended as part of a healthy diet; it’s important to understand how the fats stack up in this comparison.
Both omega-3 and omega-6 fatty acids are necessary for optimal health. These essential fatty acids are an integral part of the human diet since it’s not possible for our bodies to make them.
The tricky part is, humans evolved eating about equal parts of omega-3 fatty acids to omega-6 fatty acids, while a typical modern diet clocks in at about 1 part omega-3 to 15 or 16 parts omega-6 fatty acids. (6) The imbalance can be problematic.
Most people already eat too much of foods rich in omega-6, such as what’s found in highly processed vegetable oils.
Research suggests consuming excess omega-6 fatty acids can contribute to inflammation, which is implicated in the development of a range of chronic diseases, including diabetes, arthritis, heart disease, asthma, peptic ulcers, Crohn’s disease and sinusitis. (7, 8, 9, 10)
Despite the higher ratio between the two omega fatty acids in farmed salmon, many authorities take the position that it can still make a positive contribution to many people’s diets. Even though it doesn’t match the better score of 10 parts omega-3 to 1 part omega-6 for wild salmon, the ratio is still good at 3 or 4 parts omega-3 to 1 part omega 6. (11)
Here’s a good example of the impact adding salmon to the diet can have on health: in one small 4-week study, 19 volunteers ate farmed salmon twice weekly; these eight servings of salmon raised blood levels of an omega-3 fatty acid called DHA by 50%. (12)
Contaminants and Metals in Farmed Salmon
Fish can absorb contaminants from the water they swim in as well as the food they eat, and farmed fish contain much higher levels of several dangerous substances. (13)
Farmed fish from Chile appear to have the lowest level of contaminants, and American aquacultures rate better than European. (14)
Polychlorinated biphenyls (PCBs), chlorinated pesticides and dioxins are among the most common contaminants found in farmed fish; of these, PCBs may be the most dangerous.
When researchers analyzed samples of more than 700 farmed salmon gathered worldwide, the results showed PCB levels in farmed fish averaged about eight times the levels found in wild fish. (15)
However, farmed salmon may not have any more mercury on average than wild salmon. Two studies showed little difference, and one study showed wild salmon contained three times the amount of mercury as farmed salmon. (20, 21, 22)
Higher levels of arsenic have been detected in farmed salmon, but the amounts of cadmium, copper and cobalt are higher in wild salmon. (23)
The amounts of trace metals found in both types of fish were low enough that there’s likely no cause for concern.
When it comes to PCB levels, analysts speculate that if EPA recommendations were observed, limiting farmed salmon consumption to once a month would be the accepted guideline. Some experts believe it’s safer for children and pregnant women to eat only wild salmon.
Some may not be willing or able to take the risk of ingesting PCBs; for these folks, wild salmon is the clear winner on that score.
Cost and Availability Factors
Wild salmon is much more expensive than farmed salmon, and in some areas, farmed salmon may be the only type available.
Some believe the health benefits of salmon, including the farmed variety, justify the risk of consuming contaminants like mercury or PCBs, but this is obviously a question of personal standards.
If you’re wondering how the two types of fish stack up in regard to taste and texture, you’re not the only one with that concern.
The Washington Post assembled a tasting panel composed of distinguished chefs and other culinary connoisseurs to explore the issue. The results may surprise you: farmed salmon beat out wild salmon in nearly every session. (24)
And this was simply prepared fish, steamed and served with a little salt.
Summary: Contaminant levels are higher in farmed fish, but when cost and availability are factored into the equation, the trade-off for potential health benefits resulting from adding omega-3 fatty acids found in salmon to your diet may be worth it.