The global and regional costs of healthy and sustainable dietary patterns: a modelling study

Abstract

Background: Adoption of healthy and sustainable diets could be essential for safe-guarding the Earth's natural resources and reducing diet-related mortality, but their adoption could be hampered if such diets proved to be more expensive and unaffordable for some populations. Therefore, we aimed to estimate the costs of healthy and sustainable diets around the world.

Methods: In this modelling study, we used regionally comparable food prices from the International Comparison Program for 150 countries. We paired those prices with estimates of food demand for different dietary patterns that, in modelling studies, have been associated with reductions in premature mortality and environmental resource demand, including nutritionally balanced flexitarian, pescatarian, vegetarian, and vegan diets. We used estimates of food waste and projections of food demand and prices to specify food system and socioeconomic change scenarios up to 2050. In the full cost accounting, we estimated diet-related health-care costs by pairing a comparative risk assessment of dietary risks with cost-of-illness estimates, and we estimated climate change costs by pairing the diet scenarios with greenhouse gas emission footprints and estimates of the social cost of carbon.

Findings: Compared with the cost of current diets, the healthy and sustainable dietary patterns were, depending on the pattern, up to 22-34% lower in cost in upper-middle-income to high-income countries on average (when considering statistical means), but at least 18-29% more expensive in lower-middle-income to low-income countries. Reductions in food waste, a favourable socioeconomic development scenario, and a fuller cost accounting that included the diet-related costs of climate change and health care in the cost of diets increased the affordability of the dietary patterns in our future projections. When these measures were combined, the healthy and sustainable dietary patterns were up to 25-29% lower in cost in low-income to lower-middle-income countries, and up to 37% lower in cost on average, for the year 2050. Variants of vegetarian and vegan dietary patterns were generally most affordable, and pescatarian diets were least affordable.

Interpretation: In high-income and upper-middle-income countries, dietary change interventions that incentivise adoption of healthy and sustainable diets can help consumers in those countries reduce costs while, at the same time, contribute to fulfilling national climate change commitments and reduce public health spending. In low-income and lower-middle-income countries, healthy and sustainable diets are substantially less costly than western diets and can also be cost-competitive in the medium-to-long term, subject to beneficial socioeconomic development and reductions in food waste. A fuller accounting of the costs of diets would make healthy and sustainable diets the least costly option in most countries in the future.

Funding: Global Panel on Agriculture and Food Systems for Nutrition and Wellcome Trust.

Figure 1

Costs of diets (US$ per day) in 2017 by dietary pattern, food group, and wrold regions grouped by income BMK=benchmark diets. FLX=flexitarian diets. PSC=pescatarian diets. VEG=vegetarian diets. VGN=vegan diets. Veg=diet variant high in fruits and vegetables. Grn=high-grain diet variant.

Figure 2

Cost of diets (US$ per day) for benchmark diets and relative percentage changes by dietary pattern, world region grouped by income, and food-system scenario The food-system scenarios consist of changes in food waste (full waste vs half waste), three socioeconomic development projections to 2050 (med vs high vs low), additional halving of food waste for these development projections (med vs high vs low under half waste in 2050), external cost estimates (health vs clim), and combinations of those scenarios for the three development projections (med vs high vs low). BMK=benchmark diets. FLX=flexitarian diets. PSC=pescatarian diets. VEG=vegetarian diets. VGN=vegan diets. Veg=diet variant high in fruits and vegetables. Grn=high-grain diet variant. Full waste=no change in waste. Half waste=halving of waste. Med=business-as-usual development (SSP2). High=more favourable development with greater income growth (SSP1). Low=less favourable development with lower income growth (SSP3). Health=health-care costs. Clim=climate-change costs.

Figure 3

Change in cost for adoption of flexitarian diets in 2017, and in 2030 and 2050 when food-system measures are implemented Change in cost (%) include dietary changes to flexitarian diets in 2017 (top), and additinal food-system measures in 2030 (middle) and 2050 (bottom). The food-system measures consist of favourable socioeconomic development (SSP1), a halving of food waste, and a fuller cost accounting that includes health-change and climate-change costs in the price of foods. FLX=flexitarian diets.