Omega 3 content, more than halved in farmed salmon


In the last fifteen years, the content of marine omega 3 fatty acids has been more than halved in farmed salmon. Much less, but still enough omega 3 in one serving to cover our daily needs according to PhD fellow Amalie Moxness Reksten. She has participated in a study done by the Institute of Marine Research I Norway.


The study looked at how the content of the most important nutrients in farmed salmon has developed in the last fifteen years.

Over the last fifteen years, farmed salmon have gone from being feed with mainly marine ingredients, to more vegetable ingredients such as soy, rapeseed, wheat, corn, and sunflower. Not natural food for a fish.

– We saw the largest reduction in omega-3 from 2005 to 2011, while in recent years the levels have been relatively stable, she says.

On the other hand, the content of vitamin D has remained stable over time, while the content of vitamin B12 has increased slightly. The amount of iodine has dropped further.

– Fatty fish contains little iodine, and this is confirmed by our study. In fact, the content of iodine has decreased slightly over time, and the farmed salmon has thus gone from containing little to containing even less iodine, Reksten says.

Farmed or wild caught?

The salmon industry in Norway is booming, and Norwegian salmon exported NOK 16.7 billion in the first quarter. Nevertheless, there is cause for concern about the quality of the fish. The content of fish oil in salmon feed has decreased from 100 to 30 percent in 15 years, which means that the content of omega 3 in salmon has been halved.

Wild salmon is caught in natural environments such as oceans, rivers, and lakes. Wild fish eat organisms found in their natural environment and seems to have higher amounts of omega 3, and natural minerals, including calcium and iron. While the wild salmon often contains more minerals, farmed salmon can be higher in omega 6 fatty acids, due to the vegetable feed. 

Dioxins add an element of uncertainty

Although farmed salmon should still be considered healthy from a nutritional standpoint, it’s also an important source of substances that we don’t necessarily want to consume, like dioxins.

These are environmental pollutants that accumulate in the body. Consuming foods that contain dioxins over the long term can lead to a weakened immune system, reduced fertility, changes in hormonal balance and more. 

Farmed salmon may contain more contaminants than wild salmon, but stricter rules on feed ingredients could be closing the gap. And while both types of salmon may contain contaminants, the health benefits of eating salmon probably outweigh the risks.

Antibiotics in farmed salmon

Due to the high density of fish in aquaculture, farmed fish are generally more susceptible than wild fish to infections and disease. To counter this problem, antibiotics are frequently added to fish feed. 

Antibiotic use is not only an environmental problem but also a health concern for consumer ingesting traces of antibiotics over the long term, that may cause drug resistance, a hypersensitivity to antibiotics, and even the disruption of gut flora. 

Fortunately, many of the world’s largest producers of salmon, such as Norway and Canada, are considered to have effective regulatory frameworks. 


Written by: Anna Ingwardo, Bachelor of Nutritional Physiology.

Since 2008, she has worked as a nutritionist at Dr. Fedon Lindberg’s clinic in Oslo. Anna is particularly interested in functional medical principles and has immersed herself in the treatment of digestive-related imbalances and ailments, food hypersensitivity and leaky gut. She has also expertise in the treatment of other lifestyle-related conditions such as obesity / overweight, insulin resistance / diabetes and other hormone-related imbalances in the body. Anna is the co-author of 3 books dealing with obesity.

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