More valuable than a small steak

Eat beans, fry larvae and dig more fish ponds: German researchers have a plan to sustainably provide protein for future generations

“You are what you eat,” is a common saying. What is usually meant by this is: If you eat “healthy,” you can also increase your chances of staying healthy that way. And vice versa. From a purely physiological point of view, it simply means that apart from air and UV rays, pretty much everything that people need to live – everything they are made of, everything they “are” – has to enter them via the stomach and intestines. Most of it should also already be present in the form of usable building blocks of life. Carbohydrates, for example, provide plenty of energy, but muscle mass cannot be built up. Proteins are needed for this. Without sufficient protein, a healthy life is not possible. At the same time, however, this is also the macronutrient that currently consumes the most resources in terms of its energy content – because it comes largely from animals.

Consequently, the maxim “You are what you eat” can also be applied to humanity as a whole and the environment in which it lives. But it raises a problem: In view of the existing and future arable land in the protein sector, it is virtually impossible, in purely mathematical terms, to feed the soon to be eight billion people. At least if they are to eat enough to cover their requirements for all nutrients – and the protein sources remain the same as they are today.

How could the protein needs of the growing world population be met in the future without destroying the planet in the process? Researchers from various German Leibniz institutes and universities have now attempted to present a catalog for a protein supply strategy. Under the title “Sustainable Food Production and Healthy Nutrition,” they present their view. The “position paper” has now been published in the specialist journal “Global Food Security”.

Pretty much all relevant disciplines were involved. First and foremost, nutrition researchers contributed their expertise. After all, not all proteins are the same. Plant proteins, for example, do not have the same complete mix of amino acids that is ideal for humans as a chicken egg. Eating only cooked beans, for example, is not an ideal long-term solution. However, certain preparation methods can help turn these legumes into an almost complete protein supplier. The researchers’ key proposals also include combining plant protein sources in foods in a targeted and science-based way in the future so that this results in a full-value protein composition overall.

But to be able to do that, you have to produce those plant products in the first place. That’s why experts from the agricultural and plant sciences also contributed their knowledge. They were joined by experts in marine and freshwater ecology, entomologists, and climate and earth system researchers.

It has long been known how great the potential is. Five years ago, for example, Joan Sabaté of Loma Linda University and his colleagues calculated that “to produce one kilogram of protein from kidney beans requires about eighteen times less land, ten times less water, nine times less fuel, twelve times less fertilizer, and ten times fewer pesticides than producing one kilogram of protein from beef.” But even chicken meat and eggs have a significantly better climate and ecological balance sheet than the classic steak suppliers from the pasture and from the barn.

Legumes are also an important component in the overall nutritional-ecological picture. Their advantage is that, with the help of bacteria, they obtain the nitrogen that is important for proteins from the air instead of from climate-damaging fertilizers.

Suggestions that have so far been taken rather less seriously, such as that of relying on insect protein – even where it is not part of the culinary tradition – are also part of the picture. Here, the researchers complain that there are hardly any political initiatives to promote such alternatives. In addition, there must be an expansion of fish production in aquaculture systems. These should become much more sustainable than they are now, with less need for antibiotics and more use of recirculating systems. This could often mean integrating them with adjacent agriculture: For example, it often makes sense to use water from fish tanks for fertilization and irrigation. Aquaponics is the name of this process. In an ideally functioning aquaponics system, the plants clarify the water so well that it can be pumped back into the fish tank – thus completing the cycle.

But alongside that catalog of suggestions emerged, unsurprisingly, a catalog of unanswered questions. “Fundamentally, we need to look not only at the health impacts of our diets, but also at the indirect health impacts caused by food production – from overuse of water resources to loss of biodiversity,” says Isabelle Weindl of the Potsdam Institute for Climate Impact Research. Not even enough is known so far about the optimal protein intake in terms of health. On the one hand, there is evidence of “a health-promoting effect of high-protein diets, for example in the treatment of obesity,” says Susanne Klaus of the German Institute of Human Nutrition in Potsdam. However, epidemiological studies also suggest that a low-protein diet has a positive effect on life expectancy and the risk of disease.

One thing, however, is certain, says Susanne Klaus: people will have to “change their dietary behavior”. There is no way around a “greater proportion of plant-based foods and alternative sources of protein” in the future. Richard Friebe

Protein from the garden. There are more than 100 bean varieties in Germany alone. Through certain preparation methods, legumes can become an almost complete protein supplier.