Contribution of different life cycle stages to the greenhouse gas emissions associated with three balanced dietary patterns.

In light of the considerable pressure exerted by food production on the environment, the assessment of the environmental burdens of dietary choices has recently gained interest among the scientific community. Several studies based on life cycle thinking approach agreed that a transition from an omnivorous to either a vegan or vegetarian diets would reduce the environmental impact associated with food consumption. The majority of the studies set the system boundaries up to the retail, excluding the consumption phase and generally do not account for uncertainties. The aim of the present study was to assess how personal consumption choices and behaviour can affect the greenhouse gas emissions generated by three balanced dietary patterns (omnivorous, vegetarian and vegan), defined on the basis of nutritional recommendations for an average Italian man. It took into consideration the uncertainties associated with three elements, namely the greenhouse gas emissions due to the production of the food items, the emissions associated with cooking and the food wasted by consumers. The results of the study highlighted that, despite the higher share of greenhouse gas emissions of the supply chain stages prior to consumption (66%-74% of the total emissions), domestic behaviours have an important influence of the total greenhouse gas emissions of the diet, which can offset the lower GHG emissions due to the choice of vegetable-origin foods. In fact, 15%-21% of the total emissions are associated to the cooking phase and 11%-13% to the food waste generation. Therefore, this study remarks the importance of adopting a cradle to grave perspective when assessing the environmental burden of dietary patterns and emphasises the central role of consumers in the definition of low GHG-emitting dietary patterns.