Assessing and optimizing the relationship between nutritional quality and environmental impacts of household food consumption: evidence from the longitudinal data in urban China

Food consumption is a critical nexus that links human health with environmental sustainability. However, existing research rarely considers the relationship between nutritional upgrading of dietary shifts and their environmental impacts simultaneously, especially in urban areas with significant income disparities. Therefore, it is necessary to assess the relationships between the two in the context of income stratification and promote sustainable transformation of the food system through dietary adjustments. This study constructs an assessment indicator to quantify the relationship between nutritional quality and environmental burdens, including greenhouse gas emissions, freshwater use and land use. Then, we try to optimize current food consumption patterns to achieve a sustainable healthy diet. Our findings reveal that urban households' food consumption deviates significantly from the recommended intake, with low-income households displaying the poorest nutritional quality. The transition of dietary patterns significantly increases environmental burdens, with high-income households contributing the largest environmental footprints. As for the nexus between the two, the synergy relationship is achieved in high-income households, whereas middle-income households gain nutritional benefits at the expense of environmental health. Adopting optimized diets with less red meat can help urban households improve nutritional quality but lead to greater environmental unsustainability and economic unaffordability, especially for low-income households. We argue that there is no single optimal dietary pattern that is universally applicable to all households or residents. The finding highlights the need to focus on vulnerable socioeconomic groups, especially low-income households, when shifting dietary patterns to reconcile nutrition, environment, cost and culture.