Multi-indicator design and assessment of sustainable diet plans

In this work, a set of diet plans that are nutritionally adequate and healthy, affordable, and environmentally friendly is analyzed. They refer to two-week full-board menus for nursing homes and are designed using a multi-objective optimization model in which different conflicting goals, such as the carbon and water footprints, cost, and nutritional and acceptability requirements, are pursued. As a consequence, the design provides a set of several menus corresponding to different trade-offs between the goals. Energy and nutrient contents are constrained in suitable ranges suggested by the dietary recommendation of health authorities. The carbon and water footprints and the cost of the diet are considered as goals to be minimized. More than one hundred menus have been considered to explore all the possible trade-offs between the three goals. The analysis shows that cheaper menus are more environmentally impacting and that it is possible to make a trade-off between the carbon and water footprints while keeping the cost of the menu unchanged. Moreover, it is possible to quantify the cost increase for a given improvement either of the carbon or water footprint. On the other hand, all the menus are nutritionally adequate and, more importantly, energy and nutrient contents are almost the same despite the large differences in their carbon and water footprints, and cost. Another interesting result of this study is the analysis of the relationships between the energy and nutrient intakes of the optimal menus and their cost and environmental impacts.