Ökologische Bewertung von Ernährungsweisen anhand ausgewählter Indikatoren

Abstract

This study was undertaken to evaluate the ecological impact of currently practised diets and also to investigate reduction potentials. Therefore, indicators for the ecological evaluation were chosen. The indicators were selected according to their relevance and the availability of data. The following indicators were taken: Primary energy input, CO₂-equivalents for the evaluation of the global warming potential and for the evaluation of the acidification potential the SO₂-equivalents. These indicators were used to evaluate the overall system, additionally the losses of nitrogen, potassium and phosphorus in the agricultural system were taken into account.
Three diets were compared concerning their ecological impact. The consumption data were taken from 7-day consumption protocols from the National Consumption Study (NVS) and the Giessen Wholesome Nutrition Study (VWS). Data of the NVS were taken as the reference diet for an average German diet (MK). Data of the VWS represented diets with a special nutritional behavior characterized with a high content of unprocessed food and a low content of meat and meat products for the non-vegetarians (NVEG) or no meat consumption at all for the vegetarians (OLV).
A special cohort was chosen. They were healthy, non-pregnant women at the age of 25-65 years. In order to compare the data of the consumption protocols of the two studies, 17 comparable food groups were established. In order to evaluate the quantities of the purchased goods and not only the food actually eaten the data of the protocols was multiplied with correction factors.
The diets were assessed in two different versions, an ecological version and a conventional version, enabling a comparison of the different diets and also of the versions within one diet. These versions can be influenced by the consumer themselves directly through their shopping pattern.
The assessment was undertaken for the following areas: Agricultural production, food processing, transportation, packaging and household phase. The sum of these areas is the food-system because they represent the system in which the different diets were produced.
This study is based on a single unified database and as far as possible on data taken from well documented literature. Therefore, it was possible to compare the results of different balances of different agricultural products within the study, which i.e. would not be the case with life cycle assessments on agricultural products. The assessment of agricultural products was based on common recommendations of good agricultural practice, it was carried out for the conventional and the ecological version. Typical industrial processes were assessed for the food processing.
The food packaging data were taken from a well documented study on the topic in two versions, conventional and ecological. The overall transportation within the food system was estimated based on a statistical analysis. Data for the assessment of the household phase were taken from macroanalyses which comprised the shopping i.e. the driving to the store, the cooling of the goods and the cooking (in a conventional and an ecological version).
The ecolocigal assessment of the diets showed the highest emissions for the MK, followed by the NVEG and the OLV. The OLV, in spite of consuming the higest amount of food, showed the lowest ecological impact. A reduction potential can be realised by choosing the ecological instead of the conventional version within one diet. However the highest possible reduction protential results from a change of the MK diet in its conventional version to the OLV diet in its ecological version. Therefore, it could be shown that consumers are able to influence the ecological impact of their consumption by choosing the version within a diet or by changing their diet.