Study: Humans should eat the same diet that farmed salmon eat

As public awareness grows about the importance of sustainable food sources, scientists are now encouraging the consumption of wild fish species like mackerel, anchovies, and herring. 

These fish, often used in farmed salmon diets, offer vital nutrients such as calcium, vitamin B12, and omega-3 which are partially lost when consuming farmed salmon alone. 

Loss of essential dietary nutrients 

A study led by the University of Cambridge has recently revealed that farmed salmon production results in a net loss of essential dietary nutrients, suggesting that direct consumption of these “feed” species could not only enhance health but also ease the aquaculture sector’s reliance on finite marine resources.

“What we’re seeing is that most species of wild fish used as feed have a similar or greater density and range of micronutrients than farmed salmon filets,” said lead author David Willer, a researcher in the Zoology Department at Cambridge.

“Whilst still enjoying eating salmon and supporting sustainable growth in the sector, people should consider eating a greater and wider variety of wild fish species like sardines, mackerel and anchovies, to get more essential nutrients straight to their plate.” 

A few changes can go a long way

In the UK, 71% of adults have vitamin D deficiencies in the winter, while teenage girls and women frequently have insufficient iodine, selenium, and iron. 

According to Willer, “making a few small changes to our diet around the type of fish that we eat can go a long way to changing some of these deficiencies and increasing the health of both our population and planet.”

“Marine fisheries are important local and global food systems, but large catches are being diverted towards farm feeds. Prioritizing nutritious seafood for people can help improve both diets and ocean sustainability,” added senior author James Robinson, a research fellow at Lancaster University’s Environmental Center.

Maximizing nutrients from the sea

The experts conducted an analysis comparing the nutrient content in wild fish used in salmon feeds with the farmed salmon themselves. This revealed a decrease in six out of nine essential nutrients in the salmon filet. 

For instance, the quantity of calcium was over five times higher in wild feed fish filets than salmon filets, iodine was four times higher, and iron, omega-3, vitamin B12, and vitamin A were over 1.5 times higher. 

These findings prompted the researchers to advocate for a more efficient way of maximizing nutrients from the sea by directly consuming a portion of the current food-grade wild feed fish. 

Retaining key nutrients in farmed salmon 

According to Richard Newton, an expert in aquaculture at the University of Stirling, “farmed salmon is an excellent source of nutrition, and is one of the best converters of feed of any farmed animal, but for the industry to grow it needs to become better at retaining key nutrients that it is fed.” 

“This can be done through more strategic use of feed ingredients, including from fishery by-products and sustainably-sourced, industrial-grade fish such as sand eels.”

“It was interesting to see that we’re effectively wasting around 80% of the calcium and iodine from the feed fish – especially when we consider that women and teenage girls are often not getting enough of these nutrients,” he added.

Appealing products made of wild “feed” fish

A notable aspect of this research is the proposal for the aquaculture industry to adopt a nutrient retention metric, which Willer believes could lead to a more efficient industry that lessens the burden on fish stocks also meant for direct human consumption. 

“We’d like to see the industry expand but not at a cost to our oceans. We’d also like to see a greater variety of affordable, convenient and appealing products made of wild ‘feed’ fish and fish and salmon by-products for direct human consumption,” he explained.

Thus, the call to action from this study – published in the journal Nature Food – is not just for consumers to diversify their seafood intake but also for the aquaculture sector to reconsider its practices for the benefit of global nutrition and environmental sustainability.

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