How do regional and demographic differences in diets affect the health and environmental impact in China?

A higher diet quality has been associated with lower environmental impacts, but not consistently. Considering the cultural diversity of dietary habits and the heterogeneity of socioeconomic development in China, we aimed to evaluate the association between diet quality and environmental impacts across demographic subgroups and regions. This study used dietary consumption data from the China Health Nutrition Survey 2011. Diet quality was measured with the Chinese Healthy Eating Index 2016 (CHEI2016). Diet-related environmental impact (Greenhouse Gas Emissions (GHGE), Total Water Use (TWU), and Land Use (LU)) were estimated using the Chinese Food Life Cycle Assessment Database. Multilevel regression models were used to quantify the association of the CHEI2016 score and the diet-related environmental impacts across heterogeneous population subgroups. A one-standard deviation increase in CHEI2016 score was associated with an increase of 9.7% in GHGE, 9.1% in TWU, and 6.4% in LU. This occurs because increasing the consumption of under-consumed foods (dairy products and fruit), partially offsets the environmental benefits of reduced meat consumption. Demographic subgroups characterized by either higher educated or a higher income exhibited a larger proportion of animal-based foods within their diet, consequently leading to higher diet-related environmental impacts. When expressed per standard deviation increase in CHEI2016, the dietary environmental impacts rose fastest in the Metropolitan area and slowest in the Northeast. Diets with higher CHEI2016 scores are associated with higher diet-related environmental impacts among Chinese adults but this varies per region. The development of sustainable diet strategies needs to account for potential trade-off between the health and environmental goals, and dietary habits of consumers in different regions and subpopulations.