An optimisation study to reduce greenhouse gas emissions from adults’ current diet in Italy

Abstract

Abstract Background Trade-offs between health and sustainability dimensions should be addressed since environmentally sustainable diets can require a substantial dietary shift and result in nutrient deficiencies. The study aimed at modelling the current dietary consumption of the adult population in Italy to reduce diet-related greenhouse gas emission (GHGe) while complying with the National Recommended Energy and Nutrient Intake Levels (LARN), food-based dietary guidelines, and preferences. Methods Food consumption data from the Italian Nutrition & HEalth Survey (INHES) study (n = 8944, 53% females) have been used as reference diet. Through a non-linear programming model, two intermediate nutritionally adequate dietary scenarios, which alternatively minimised the impact on climate change or modifications in current food consumption, have been generated contextually to a final diet model combining both outcomes. Several constraints ranging from recommended dietary intakes to proper food associations and substitutions were applied to the model. Results The final modelled diet had an average energy content of 2100 kcal/d with carbohydrates, proteins, lipids, and fibers accounting respectively for 49%, 16%, 31%, and 4% of the total energy. The associated GHGe were 2.01 kg CO2 eq/d: 49% less than the current diet, 22% more than the balanced diet with the lowest GHGe, and 12% less than the balanced diet closest to actual food consumption. Wholegrain bread, peas, seasonal fruit and vegetables, chicken, tuna, whole milk and extra-virgin olive oil were the most represented products within each corresponding food group. Conclusions The study proposes a balanced and climate-friendly diet which simultaneously minimises changes in food preferences, reducing barriers towards more sustainable food choices. Diet optimisation can be a promising tool to support public health strategies by suggesting less environmentally impactful and culturally acceptable dietary shifts at the country level. Key messages • The present study provides a culturally acceptable and nutritionally balanced dietary scenario optimised for greenhouse gas emissions to be proposed as a model for the adult population in Italy. • The study contributes to the development of public health policies by supporting feasible dietary behavioural shifts towards healthy and sustainable dietary choices.