In the last 10–15 years, the content of marine omega-3 fatty acids in farmed salmon feed has decreased, which means that there is also less of these fatty acids in the salmon itself. The reason is that the marine ingredients in fish feed have been increasingly replaced by vegetable ingredients.
This does not mean that farmed salmon contains low levels of marine omega-3, just that it contains less than before. Although the marine omega-3 levels have been reduced by around 60 per cent, farmed salmon continues to be a good source of the healthy fatty acids, according to Bente Torstensen, Director of Research at NIFES. And so it will always be, because Atlantic salmon needs these fatty acids to meet its own nutrient requirement.
‘Marine omega-3 is not only important to people, but to the salmon as well. That is why farmed salmon will always contain a lot of marine omega-3. It needs a certain amount of marine omega-3 to grow and have good health and welfare,’ she says.
Fat for the brain and the heart
In addition, having too much marine omega-3 in the salmon’s feed is not very resource-efficient, according to Torstensen.
‘The salmon only needs a certain amount of omega-3, and if it is given too much of the fatty acids, it uses any excess omega-3 as energy instead of storing it,’ says the Director of Research.
The most important marine omega-3 fatty acids are EPA and DHA, and they have several benefits for people. Both fatty acids prevent development of cardiovascular diseases. In addition, DHA is particularly important to the development of children and young people’ brains, and to ensuring optimal brain function throughout our lives.
This is one of several reasons why the Directorate of Health recommends that we eat two to three seafood meals a week, including one meal of fatty fish.
Today, one dinner portion of farmed salmon will cover more than a week’s recommended intake of marine omega-3 for healthy people in order to prevent development of cardiovascular disease.
We also need plant omega-3
Now that there are more vegetable ingredients in fish feed than before, there is also more plant omega-3 (alpha-linolenic acid) than marine omega-3 in the farmed salmon fillets. According to Torstensen, the ratio between vegetable ingredients and marine ingredients is around 70-30.
‘Plant omega-3 is an essential fatty acid that we need to include in our diet in order to stay healthy,’ she says.
In addition, both people and salmon have the ability to convert plant omega-3 into marine omega-3, but this process is not efficient enough to produce enough EPA and DHA to ensure optimal health and development. That is why the Norwegian health authorities recommend that everyone should eat one dinner portion of fatty fish per week or fish as a sandwich topping – both of which contain EPA and DHA. Pregnant women are also recommended to eat 200 milligrams of DHA every day, according to Torstensen.
One dinner (150 grams) of today’s farmed salmon contributes an average of 1.9 g EPA and DHA and 1.3 g plant omega-3.
NIFES also monitors the levels of undesirable substances in farmed salmon, and a thorough analysis shows that for most substances, the levels in farmed salmon have decreased in the past decade.