What is the most environmentally friendly diet
The climate diet: sustainable nutrition (not) made easy
When it comes to nutrition, it is no longer just about eating healthy and balanced food. It is also becoming increasingly important to protect our planet, use resources sparingly and take care of future generations. But even if you want to shop sustainably as a consumer, this is sometimes difficult. Often important information is missing in order to be able to consciously reach for environmentally friendly products in front of the supermarket shelves.
A menu for the world to save our planet
Science is currently very intensively concerned with the environmental aspects of our food, and studies on this topic are published on an ongoing basis. In this context, the term "life cycle assessment" is often mentioned - also known as life cycle analysis or LCA (for Life Cycle Assessment). This is understood to mean the potential impact of a product on the environment, throughout its entire life cycle, from manufacture and use to disposal. When it comes to the central question of how we can eat healthily and sustainably at the same time, the EAT study is often quoted¹. In it, scientists proposed a nutrition plan that should both support health and conserve the earth's resources. Accordingly, we should all change our diet as quickly as possible in order to save our planet. To do this, we should eat half less meat and sugar, but twice as much fruit and vegetables, and cover our protein requirements with pulses and nuts.
Influence of our diet on the environment
How does the way we eat affect climate change, biodiversity and our water resources? If so-called greenhouse gases are emitted in high concentrations, it is harder for heat to escape from the earth into space, and this leads to a rise in temperature on our planet. Above all, carbon dioxide (CO2) is known to be one of the main causes, but other gases such as methane or nitrous oxide also play an important role. The main sources of greenhouse gases are agriculture, as well as energy and heat generation and transport, with agriculture accounting for up to 30 percent of greenhouse gases. Methane gas is 25 times more climate-effective than CO2 and is produced, among other things, during the digestive process of ruminants (cattle, sheep, goats). Laughing gas is only emitted in small quantities, for example through nitrogen fertilization or factory farming, but it is 298 times more climate-effective than CO2.² Carbon dioxide is created during the production of fertilizers and fuels as well as the processing and transport of food, but also through clearing of natural areas. Agriculture could, however, take targeted countermeasures and, for example, compensate for the negative effect by afforestation or planting of ground cover
Food production has the greatest impact on the loss of biodiversity (species diversity). For example, natural ecosystems are being destroyed by deforestation to create new space for plantations, fields or pastures. Even monocultures with large-scale use of pesticides and herbicides leave no living space for animals or space for wild plant islands. The destruction of riparian regions by unsustainable aquaculture and the overfishing of the seas also contribute to the decline in biodiversity.¹ ³
Water is a precious commodity and is slowly becoming scarce on our planet. Scientists are already warning of a water crisis in the near future.⁴ Around 70 percent of the world's freshwater resources are consumed by food production in the form of watering plants, watering animals and processing food. What is important is the difference between the use of freshwater from bodies of water or groundwater and the use of natural precipitation. Measures to reduce evaporation from the soil and water-saving irrigation methods reduce water consumption, but at present the overexploitation of water resources still predominates. Due to the massive use of fertilizers and pesticides in some regions, agriculture is also largely responsible for water pollution.³ What many consumers may not even be aware of: The production of meat requires enormous amounts of water. For example, one kilo of beef consumes around 16,000 liters of water - for one kilo of tomatoes, on the other hand, "only" around 180 liters.
The life cycle assessment of food
There are currently numerous initiatives to be able to create not only a CO2 footprint for food, but also an ecological balance. However, this is a difficult undertaking, since in addition to the influence on the climate, biodiversity and water consumption, other factors must also be taken into account: The production of phosphates and nitrates (fertilizers), pesticides and herbicides as well as the effects of the use of agricultural machinery must also be taken into account become. The processing of the food, such as the grinding of the grain or the roasting of the coffee, as well as their transport and storage are also added. The quality of the soil or its reduction through overuse also play a role. In the case of grazing cattle, a survey must be made as to whether or not they are kept on soils unsuitable for arable farming. In the case of livestock, it also depends on whether the methane gases produced are used in biogas plants or are only emitted. For all farm animals, their diet must be taken into account - none of the studies taking animal welfare into account.
The long-term goal of current efforts is to create transparency in the food sector. An indicator is to be developed that shows the ecological effects of products. In the future, for example, consumers should be able to recognize that the canned tomatoes on the shelf were harvested in Italy, but were then shipped to China and packed in cans, only to end up in Europe after a long journey home.
Food distribution imbalance
Many studies cite economic and population growth as a threat to our environment. The world population currently comprises around 7.7 billion people and is growing steadily. When it comes to nutrition, there is great inequality on our planet: around 820 million people worldwide are undernourished and around two billion are insufficiently supplied with all nutrients. Conversely, people in rich countries and increasingly also in the so-called emerging countries consume too much: If this part of the world population alone did not consume an average of more than 2,200 (as recommended by the WHO) up to a maximum of 2,500 kilocalories per day, then that would become one contribute to a significant reduction in environmental pollution. At the same time, this restriction would also be good against obesity and related diseases. It is also very important how the large amount of food waste can be reduced.¹ ² There are currently many initiatives in this area to counteract food waste.
Outsourcing of environmental damage
Almost every purchase of food has an indirect impact on the environment in other, mostly distant, countries. Researchers call this indirect consumer responsibility for global environmental impacts "teleconnection". It should make us think that Europe and North America have relocated 90 percent of the environmental damage caused by their food consumption to other regions of the world, especially to tropical regions
When it comes to the consumption of meat and dairy products, cattle and cows generally have a poor environmental balance, including organic farming. They serve us not only as meat producers, but also as milk producers. High-yielding cows need large amounts of imported concentrated feed such as soy or grain in order to produce a high milk yield. If we were to keep more robust cattle and feed them appropriately with grass or hay, then milk and dairy products would only be produced in much smaller quantities. It is similar with meat: even if it comes from domestic animals, the feed is mainly imported and the associated environmental pollution is outsourced. Reducing our meat and milk consumption could therefore make a significant contribution to relieving the burden on the environment. In the case of dairy products, butter and other products with a high fat content are particularly harmful to the environment, but lean products are significantly less. Poultry and pork have a significantly better ecological balance than beef or lamb, but they are still much worse than vegetable products.
Since many types of fruit and vegetables have a high demand for water, these too can be an example of negative teleconnection. In water-rich countries, water consumption is not a major problem, but it is in hot and dry countries. This does not only apply to distant countries; Southern Europe already has major problems here.
Sustainable nutrition made difficult
There are some easy steps that consumers can take to help protect the environment with their diet. For example, buying fresh, regional, seasonal and, if possible, unprocessed products is an important contribution to sustainability. But after that it gets difficult. There are so many complex things that play a role in the environmental impact of food that consumers, despite their good will, often do not choose climate-friendly products because they are simply not informed enough about them.
For example, what is more sustainable if a supply of locally produced fruit and vegetables is not possible? The import of fresh fruit from southern countries, the local cultivation in heated glass houses or frozen goods? In principle, one would have to check the following factors in order to be able to make a clear statement and make appropriate recommendations: The transport routes, the cultivation conditions in the country of origin, the energy consumption in the greenhouse - including the question of whether renewable energy was used here or not - as well as the electricity consumption of the Cold chain.
And what about buying apples? Local apples that are stored in cold stores have forfeited their sustainability bonus in the spring, fresh apples from Chile or New Zealand are now cheaper in terms of climate than the local stored goods. Frozen vegetables have about twice as high a carbon footprint as fresh vegetables, but on the other hand, depending on consumption habits, they can drastically reduce food waste because half of the fresh vegetables do not rot in the consumer's refrigerator. The transport of fresh produce alone may cost less CO2 than cultivation in a greenhouse, but the overexploitation of water resources in the country of origin was not taken into account.
It often takes a lot of scientists to be able to make clear statements, and it becomes complicated for consumers. There are already some comparative calculations on the ecological balance of our diet, but almost always only the effect on global warming is determined and no further data are taken into account. Consumers are left with general uncertainty here. After all, there are already a few, albeit few, initiatives that address this problem and aim to provide consumers with better information - an exciting, but certainly not that easy task.
Many consumers today want to eat both healthy and sustainable. A significant reduction in our meat and dairy product consumption and a lower total calorie intake can make an important contribution to protecting the climate and the environment. Not shopping too much and not letting any food go to waste protects our planet, as does the occasional conscious avoidance of unnecessary food such as sweets, snacks or alcoholic beverages. In terms of sustainability, it should also be questioned where products come from and under what circumstances they were produced, not only when shopping, but also when eating out. In the future, it will hopefully be easier for consumers to shop in the supermarket in an environmentally conscious manner, because many countries are currently working on specific indicators for the ecological balance of food. (Isolde Jansen, October 21, 2019)
Isolde Jansen is a cultural scientist and has worked for Open Science for many years. She is one of the bloggers who write the articles for the Hungry for Science blog from Open Science as "better knowledgeable".
You can find more articles on hungryforscience.at.
1 Willett W., Rockström J., Loken B. et al .: Food in the Anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet. 2019 Feb 2; 393 (10170): 447-492.
² greenhouse gases (German Federal Environment Agency)
3 Ridoutt B.G., Hendrie G.A., Noakes M. Dietary Strategies to Reduce Environmental Impact: A Critical Review of the Evidence Base. Advances in Nutrition, Volume 8, Issue 6, November 1, 2017, Pages 933–946
⁴ The water crises of the future (WWF)
⁵ Marques, A., Martins, I.S., Kastner, T. et.al: Increasing Impacts of land use on biodiversity and carbon sequestration driven by population and economic growth. Nature Ecology & Evolution (2019).
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