Fish, health, and sustainability: What to know

As many people try to improve their diet by cutting down on red meat, fish seems like a good healthy option. However, the sustainability of eating fish has increasingly been called into question. Here, we investigate the health claims and arguments for and against eating fish and explore some alternatives.

Some people consider fish to be a healthy alternative to red meat. It is a good source of protein, omega-3 and omega-6 fatty acids, and several minerals and vitamins.

Omega-3 fatty acids, which, as research has shown, can have a positive effect on heart health, are present in high concentrations in oily fish, such as salmon and mackerel.

Research indicates these fatty acids can also promote greater blood flow to the brain, which is vital for delivering oxygen essential for brain function. And one study has suggested that omega-3s may have a role in healthy brain aging.

Eating fish may also combat inflammation: a recent study found that regular consumption of fish helped reduce the incidence of chronic inflammatory conditions and may even benefit the immune system.

Medical News Today spoke to Kate Cohen, Registered Dietician at the Lawrence J. Ellison Institute for Transformative Nutrition of USC, to find out the science behind some of these claims.

“Fish and shellfish are the main sources in our diet of the polyunsaturated fats, DHA [docosahexaenoic acid] and EOA [eicosapentaenoic acid], which are associated with brain development in pregnancy and linked to a number of potential overall health benefits,” she said.

But not all fish are equal. “Cold-water fish have a higher amount of fat to keep the fish warm in icy waters, but this also loads the fish with beneficial omega-3 and omega-6 fatty acids,” she added.

Choose carefully

However, there are some concerns about the high levels of mercury in some of these cold-water fish. Suitable options with high concentrations of beneficial fatty acids and low mercury levels are wild salmon, sardines, rainbow trout, and Atlantic mackerel.

And what of white fish and shellfish? Lower in calories than oily fish, they do not contain high levels of omega-3 but are a good source of lean protein and many minerals and vitamins, such as iron, zinc, and vitamins A, B12, and D.

Cohen recommended including fish in your diet 2–3 times a week to get the benefits, but advised that you “rotate your fish. Your body needs all the different vitamins and minerals available in fish, so don’t stick with just one kind.”

Is wild-caught fish sustainable?

Shocking images of waste, environmental pollution, and bycatch (catching a species of fish or marine species unintentionally), including marine mammals, turtles, and seabirds, have led many to question whether the health benefits of fish and seafood are worth the environmental costs.

The Marine Stewardship Council (MSC) regulates fisheries in the U.K., with organizations such as Monterey Bay Aquarium Seafood Watch fulfilling a similar role in the United States. The MSC refutes the claim that there is no such thing as sustainable fishing, outlining three principles for sustainable fisheries: sustainable fish stocks, minimizing environmental impacts, and effective fisheries management.

The MSC states that “fish stocks can recover and replenish if they are managed carefully for the long-term.” Its website includes a list of fish that are sustainable when they carry the MSC label.

In the U.S., the Washington-based Environmental Working Group (EWG) goes further, giving a regularly updated list of fish that are both healthy — in terms of contaminant levels — and sustainable. Similar information is listed on the U.S. government’s Fishwatch.

Josep Lloret, Director of Oceans and Human Health Chair at the University of Girona, Spain, agreed that sustainable fishing is possible but challenging: “Artisanal (small scale) fisheries are seen as the most sustainable, but even these have their own environmental footprints, such as the impact on vulnerable species due to selectivity issues.”

“Marine Protected Areas (MPAs) can be effective if they are well implemented and well managed. However, many MPAs around the world lack a proper management plan,” he added.

There is some good news. According to the European Environment Agency, there are signs of recovery in the North-East Atlantic Ocean and Baltic Sea.

However, it states that further collective action is necessary to regain healthy commercial fish and shellfish populations in European waters. In the U.S., despite overfishing, some stocks are starting to recover because of the careful management of fisheries.

“Seafood is a healthy option compared to meat, but if we follow doctors’ recommendations of omega-3 fatty acid intake, with the expected rise of the human population, we will very quickly deplete our seas.”

— Josep Lloret, University of Girona

What is the alternative?

So, if wild fish stocks cannot supply the amount of fish needed for optimal intake of fatty acids, where can the fish originate?

An obvious alternative to wild-caught fish is fish farming, or aquaculture. There are no issues with bycatch, the fish is cheaper to buy, supply is more reliable, and there is less effect on wild habitats. But is farmed fish as good for us as wild-caught fish?

“It really comes down to what the fish eats and its environment,” said Cohen. “Farmed salmon, for example, can have about 40% more calories than wild salmon and about 50% more fat — which is a pretty huge difference.”

She added that “there is also a greater risk of contaminants in farm-raised fish that are kept in small, enclosed pens, as well as antibiotic exposure from the farms’ attempts at disease prevention.”

There is also concern about the food that these farmed fish eat.

Josep Lloret commented: “Farmed fish have several problems, including the need for forage fish to feed them (then the forage fish get overexploited), compared to land, we raise ‘lions’ at sea (predators, such as sea bass, that consume a lot of forage fish), [and there is] impact on sea bottoms because of pollution.”

Pollution concerns

One way of minimizing this pollution is by combining different types of aquaculture, as outlined in a 2020 report by the Food and Agriculture Organization of the United Nations (FAO).

If fish farmers grow an extractive species, such as filter-feeding mussels, near fish pens, the mussels remove the waste from the water. And those bivalves are a nutrient-rich, low-mercury seafood themselves.

Organizations, such as the Aquaculture Stewardship Council, promote responsible aquaculture and provide certification for farms that meet their standards through independent inspections.

And fish farming organizations are looking at alternatives to fish-based feeds, such as soy, canola, and seaweed, which provide the omega-3s that fish need.

Fish without the fish

But what about those who do not eat fish — either because they dislike it, have allergies, or are vegetarian or vegan for ethical reasons?

According to Cohen, fish are the best source of DHA and EPA. Other marine foods, such as algae or seaweed, are an option, and omega-3s are also present in grass-fed beef and eggs from chickens that have flaxseed in their diet.

Vegetarian and vegan alternatives to fish are available and do not have sustainability issues, but do these have the same nutritional benefits as real fish?

Food producer Novish, which makes plant-based fish sticks, nuggets, and burgers, states that its products, now available through multinational seafood chain Nordsee, contain no soy or artificial additives. And to give the fishy taste, the brand flavors its foods with seaweed and algae.

But Cohen advised consumers buying fish alternatives to check carefully: “Try to avoid plant-based alternatives to fish that involve multiple mysterious ingredients since it’s ultimately just processed food.“

The Good Food Institute Europe (GFI), an organization that advocates alternative proteins, has launched a sustainable seafood initiative to promote plant-based, cultivated, and fermentation-derived alternatives to fish.

It states that “companies are able to turn plant ingredients into end products that create the sensory experience and nutritional profile of conventional seafood.”

Grown in the lab

Most manufacturers make plant-based “fish” into products, but a new development — cell culture — involves growing fish in the lab from cells. This can create fish fillets without the bones or scales, but it is still in its early stages.

U.S. food producers Wildtype and BluNalu are both working on these products. BluNalu claims they will “be free of harmful levels of mercury, pathogens, parasites, microplastics, and other environmental contaminants,” and they will “have the same taste, texture, and performance as conventional seafood in all cooking and preparation methods.”

And the GFI adds: “Though not yet commercially available, cultivated seafood is identical to conventional seafood at a cellular level — but is free from mercury, heavy metals, and antibiotics.”

However, Cohen is not convinced: “There is no clinical data about the comparison in nutrients between real fish and fish created in a laboratory. My hope is that we will put more energy into improving sustainable farming and fishing practices to continue addressing environmental concerns and putting fish on everyone’s table.”

Healthy and sustainable?

So should we eat fish? The nutrients in fish are important, but it is possible to get them elsewhere if you are concerned about sustainability issues.

And the key to a healthy lifestyle is ensuring that your diet is varied. Cohen stressed that it is not just about eating fish: “Research has shown that diets that incorporate these healthy fats — like the Mediterranean Diet — are associated with positive health outcomes. Aim for a whole-food diet whenever possible.”

The message, therefore, is that if you want to eat fish, read the label carefully to ensure it is from a sustainable source and choose cold-water oily fish for the greatest health benefits as part of a balanced and varied diet.

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