Which diet is better: moderate meat consumption and eat more fruit, vegetables and whole grain products, as recommended by the German Nutrition Society? Follow the example of Germany’s southern neighbors and eat more fish and seafood? Or even switch completely to a vegan diet? A new study by the University of Bonn (Germany) shows that the answer to these questions is not as clear-cut as one might think – depending on the exact effects you look at. The results will be published in the journal Science of the Total Environment.
Every EU citizen consumes 950 kilograms of food and drinks annually – a considerable amount, the weight of a small car. Food is responsible for a quarter of human greenhouse gas emissions worldwide. A large part of this can be traced back to farm animal husbandry: animals convert only a small part of the calories they consume into meat. Ruminants also produce methane, which further accelerates global warming.
In addition, our diet also has an impact on our health and animal welfare. When comparing diets, these aspects should also be taken into account. Experts also refer to the optimal health of humans, animals and the environment as the “One Health” perspective. “Studies that apply this perspective to nutritional issues are still rare,” explains Juliana Paris from the Center for Development Research (ZEF) at the University of Bonn.
Actual feeder compared to three alternatives
Paris, together with colleagues, has carried out an analysis that aims to close this research gap to some extent. “To do this, we looked at examples of which products are on people’s food baskets in North Rhine-Westphalia,” she explains. “We then compared this reference diet with three different scenarios: a changeover according to the recommendations of the German Nutrition Society (DGE), a changeover to a Mediterranean diet with more fish and seafood and a changeover to a vegan diet.”
In each of these three scenarios, the foods were selected so that they differ as little as possible from the reference diet. “That means, for example, that we have increased the proportion of fish and seafood, vegetables and cereal products in the Mediterranean variant,” says Paris. In addition, the entire product selection should contain the same nutrients in similar amounts as before. This gave the researchers a food basket for each scenario, which they then analyzed further.
“We relied on various databases for this,” says Dr. Neus Escobar from the Institute for Applied Systems Analysis in Austria, who supervised the work. “They enabled us, for example, to estimate the effects of each diet on certain environmental aspects – such as the amount of greenhouse gases that are produced during their production or the water consumption. We took a similar approach to the health effects of each diet. ”Red meat, for example, is known to increase the risk of certain types of cancer and cardiovascular disease.
The researchers estimated the consequences for animal welfare on the basis of several indicators. This included how many animals lose their lives through ingestion and under what conditions they are kept. “But we also used the number of neurons or the size of the brain in relation to the body in order to estimate the extent to which the respective animals actually suffer when they are used,” explains Juliana Paris.
Fish instead of steak: good for the environment, bad for animal welfare
Any of the three diets would be sustainably beneficial from the one health perspective. However, this is also at the expense of other aspects. The vegan diet does best in many areas. However, the production of vegan foods is associated with increased water consumption. “Vegans also have to consume certain nutrients separately, such as vitamin B12, vitamin D and even calcium,” says Paris.
The Mediterranean diet (albeit healthy) also leads to an increased need for water due to the high proportion of nuts and vegetables. In addition, if – as assumed in the study – the meat consumed is completely replaced by fish, the effects on animal welfare are surprisingly negative: Since fish and seafood are much smaller than, for example, cows or pigs, significantly more animals suffer as a result of this diet. The increased honey consumption, which requires intensive management of the bee colonies, also has a negative effect. “It would therefore be an advantage if you covered all of your protein needs less from animal sources,” emphasizes Neus Escobar. “In addition, many people today eat significantly too richly. If they reduce their amount of food to what is really necessary, this can have additional positive effects.”
According to the study, the DGE recommendations are a step in the right direction. However, in terms of human health, the other two options are better. Nevertheless, the data also show here: Those who avoid meat more often and instead put whole grains, vegetables and fruit on the plate are not only doing something good for themselves, but also for the animals and the environment.