Ignoring food affordability biases environmental assessments of China's healthy diet transition

The Chinese Dietary Guidelines (CDG) establish benchmarks for healthy dietary transitions. Yet complying with CDG can be expensive, putting the recommended diet out of reach for many low-income populations. Previous studies assume universal adoption of CDG, overlooking food affordability concerns and thereby biasing environmental impact estimates of dietary transitions. This study integrates affordability as an economic constraint into the traditional CDG to formulate optimized versions for China's rural populations. Using the recent household consumption data (2015) and a multi-regional input-output (MRIO) model, we estimate four environmental footprints of their anticipated dietary shifts. We found that neglecting affordability constraints can lead to an overestimation of environmental burdens related to GHG emissions (0.49 Gt CO₂-eq), land use (25.29 kha), and eutrophication (1.85 Mt PO₄-eq), while underestimating the benefits in water use, which could potentially save 0.24 Bm 3 . On average, when affordability constraints are incorporated, the estimated environmental footprint of expected dietary transitions is approximately 38.4 % (95% CI: 37.6–40.0 %) lower than that of the original CDG scenario. Dairy and beef collectively account for 44.2–83.3 % of this reduction, which is mainly attributable to rural populations' limited food budgets. Our findings highlight that incorporating affordability considerations for vulnerable populations is essential in promoting healthy dietary practices. Such integration is crucial not only for enhancing the real-world adoption of official guidelines but also for providing reliable evaluations of the environmental impacts linked to food system transformations. • Food affordability constraints are integrated into environmental assessment. • Omitting affordability overestimates the diet-related environmental footprint by ∼38.4 %. • Dairy and beef are the most budget-constrained foods. • Economic accessibility is essential for realistic dietary guidelines.