The environmental cost of subsistence: Optimizing diets to minimize footprints

Abstract

The question of how to minimize monetary cost while meeting basic nutrient requirements (a subsistence diet) was posed by George Stigler in 1945. The problem, known as Stigler's diet problem, was famously solved using the simplex algorithm. Today, we are not only concerned with the monetary cost of food, but also the environmental cost. Efforts to quantify environmental impacts led to the development of footprint (FP) indicators. The environmental footprints of food production span multiple dimensions, including greenhouse gas emissions (carbon footprint), nitrogen release (nitrogen footprint), water use (blue and green water footprint) and land use (land footprint), and a diet minimizing one of these impacts could result in higher impacts in another dimension. In this study based on nutritional and population data for the United States, we identify diets that minimize each of these four footprints subject to nutrient constraints. We then calculate tradeoffs by taking the composition of each footprint's minimum diet and calculating the other three footprints. We find that diets for the minimized footprints tend to be similar for the four footprints, suggesting there are generally synergies, rather than tradeoffs, among low footprint diets. Plant-based food and seafood (fish and other aquatic foods) commonly appear in minimized diets and tend to most efficiently supply macronutrients and micronutrients, respectively. Livestock products rarely appear in minimized diets, suggesting these foods tend to be less efficient from an environmental perspective, even when nutrient content is considered. The results' emphasis on seafood is complicated by the environmental impacts of aquaculture versus capture fisheries, increasing in aquaculture, and shifting compositions of aquaculture feeds. While this analysis does not make specific diet recommendations, our approach demonstrates potential environmental synergies of plant- and seafood-based diets. As a result, this study provides a useful tool for decision-makers in linking human nutrition and environmental impacts.

Evaluating the Water Footprint of the Mediterranean and American Diets

“…As this study has shown, changing consumption patterns towards recommended diets based on a high intake of vegetables, fruits and fish would deliver significant water savings, in some cases larger than those associated to increasing efficient production. But this message is less likely to be embraced by the general public because of the lack of knowledge about the environmental impacts of current consumption patterns and in particular linked to the diets [54,55]. This study demonstrates how important diets are for consumers and the environment, and supports other studies which argue that diets do matter when referring to sustainability [45,56].…”

Improving diet sustainability through evolution of food choices: review of epidemiological studies on the environmental impact of diets

“…This highlights the potential lack of analysis of other environmental impacts such as the water or nitrogen footprint of self-selected diets. Nevertheless, food GHGEs were found to strongly correlate with water eutrophication and air acidification, 13 and decreases in diet-related GHGEs tended to correspond with decreases in water use, nitrogen release, and land use, 67 suggesting the relevance of GHGEs as a marker of the environmental impact of diets. Other sustainability dimensions such as biodiversity should still be considered.…”

The Global Food‐Energy‐Water Nexus

“…Although a consumption focused approach to food security may be difficult to implement, given the social and cultural associations of diets, new studies have demonstrated linkages between sustainable dietary choices and health (Tilman & Clark, ) and explored sustainable diets (Gephart Davis, et al, ). Thus, approaches based on health awareness can also improve environmental sustainability.…”