A healthy diet that is also climate-friendly. More and more people are striving for that. Then you should eat less meat and more sea creatures, researchers advise. Even if you have to consider many aspects.
A diet based more on fish and seafood would protect the climate compared to conventional meat consumption and would also be healthier. This is the report of an international research team after a comprehensive comparison of data on dozens of marine animals as well as pigs, cattle and chickens. Friederike Ziegler's team from the state Research Institutes of Sweden (RISE) advises in the journal "Communications Earth and Environment" to specifically promote the consumption of such foods - especially with a view to those species with a particularly favorable climate and nutrient balance.
The team writes that the consumption of food from the sea is increasing, referring to the growing world population and increasing prosperity. According to this, in 2017 the consumption of sea creatures represented about 17 percent of human consumption of animal protein. 'There is strong evidence that the health benefits of seafood outweigh the potential risks such as contamination,' the team notes. Sea animals not only contain a lot of protein, but also omega-3 fatty acids and ingredients such as vitamin D, vitamin B12, selenium, iodine, iron, zinc and phosphorus.
While the environmental impact of eating meat has been compared to that of sea creatures on numerous occasions, such analyzes are tricky, the researchers say. On the one hand, environmental consequences are complex and range from land use to greenhouse gas emissions. In addition, marine animals are extremely diverse and, in addition to various groups of fish, also include crustaceans and mussels, which can either be caught in the wild or kept in aquaculture.
In their analyses, Ziegler's group did not relate the climate-damaging greenhouse gas emissions to the mass of a food in kilograms, but to the nutrient density. But even this is not easy: Because the emissions are strongly related to the production conditions, and the nutrient density also depends on which ingredients are referred to.
On average, Ziegler and colleagues write, marine animals have a better nutrient density than pork, beef and chicken and a better climate balance than at least pork and beef. However, the differences between different groups of marine animals varied by a factor of more than 10, especially with regard to emissions.
The emissions from wild-caught fish therefore depend primarily on fuel consumption, which in turn varies with the type of fishing and the size of the stocks. For example, line fishing for tuna - such as bigeye and albacore - is much more energy-intensive than net-catching species such as yellowfin and skipjack.
According to the study, the best ratio between nutrient units and emissions is found in wild-caught salmonids (Salmonidae) - such as pink salmon and sockeye salmon -, smaller fatty fish such as herring, mackerel and anchovies, and cultivated mussels. However, these are not the most consumed sea creatures, the team writes, pointing out, for example, that the catch of salmon fish depends on stocks and smaller fish often have to be used as fodder for aquaculture and livestock farming. In contrast, crustaceans such as crabs and shrimp or cephalopods such as octopuses had a lower nutrient density and were associated with high emissions.
While the nutrient density of individual species can hardly be changed, the emission balance can be strongly influenced, the team emphasizes, referring to technologies or - in the case of aquaculture - to husbandry conditions such as the feed used.
The greatest nutritional benefits of sea food compared to meat are based on the content of niacin, vitamin D and especially vitamin B12. White fish - i.e. fish with white meat such as cod, cod or carp - has an unfavorable nutrient density and emission balance. In view of the outstanding importance of this group as food fish, the team emphasizes that white fish kept in culture have a better balance than wild conspecifics.
The researchers admit, however, that the nutrient density of many edible fish is not yet known in detail, and the bioavailability - i.e. to what extent the body can utilize the substances - is also unclear.
In view of their results, the researchers advise making fisheries and aquaculture more climate-friendly and promoting the consumption of marine animals. To do this, you also have to get the food industry and retail on board. Better knowledge of nutrient values and appropriate labeling - as intended by the EU Commission in its Green Deal - could therefore enable the world's population to be supplied with food in a better and more environmentally friendly way.
"In fact, from a global perspective, it may be prudent to promote the most nutrient-dense forms of seafood in underserved populations, even if it results in higher emissions," it says. "By contrast, consumers in other populations may pay more attention to emissions than to nutrient content when choosing products." How increased consumption of marine animals can affect the populations of the respective species was not part of the study.