Environmental impact, nutritional adequacy, and monetary cost of current compared with healthy and sustainable diets...

Current food systems contribute to environmental degradation and resource overuse. Healthy and sustainable diets (HSDs)may help mitigate these impacts; however, their cost and nutrient adequacy can differ from current diets depending on the diet scenario. Evidence remains limited in middle-income countries such as Mexico.

This study aimed to estimate the environmental impact, monetary cost, and nutrient adequacy of 7 HSD scenarios compared with current diets among Mexican adults.

This modeling study used the DIETCOST tool to simulate food baskets (FBs) for 7 HSD scenarios: the Mexican Healthy and Sustainable Dietary Guidelines (MHSDG), the EAT-Lancet Healthy Reference Diet (EAT-HRD) and its Mexican adaptation, the Milpa diet, and 3 plant-based diets (vegetarian, vegan, and pescatarian). The current diet was modeled from Mexican National Health and Nutrition Survey 2012 and 2016 data at 2 energy levels: the observed mean (2263 kcal) and an isocaloric version (2051 kcal), matching HSDs energy targets. Nutrient adequacy was assessed using estimated average requirements. Food prices were obtained from the National Institute of Geography and Statistics and standardized to 2016 Mexican pesos (MXN). Environmental indicators (carbon footprint, land use, water footprint, and biodiversity loss) were drawn from Mexican-specific and international data sources. All comparisons were assessed using linear regression models.

HSD baskets were 12%-25% less expensive than the current diet and 3%-18% less expensive than isocaloric diets. The vegetarian FBs had the lowest cost (-24.7%), followed by EAT-HRD and Milpa (∼-20%). Land use for HSDs was 23.6%-53.2% lower, with the vegan FBs showing the lowest impact. Water footprint was lower for Milpa (-18.2%) but higher for vegan (+2.3%) and MHSDG (+5.1%) compared with current FBs. Plant-based diets had a 63%-81% lower carbon footprint and biodiversity loss (∼98%). Most scenarios met nutrient adequacy, except for vitamin B12 in vegan and vegetarian baskets and vitamin D in all.

All HSDs have lower cost and environmental impact compared with the current Mexican diet. Despite some nutrient inadequacies, they offer a feasible foundation to guide sustainable public health nutrition strategies in Mexico.