Regional food preferences influence environmental impacts of diets

Abstract

Dietary changes, mainly in developing countries, will be the major driver for an increase in environmental impacts of the global food system. Many assessments of these impacts have used the food patterns of high-income countries as the reference. However, it is questionable whether people in very different socioeconomic, cultural, and biophysical contexts will adopt the food pattern of Western Europe or North America. This paper explores the environmental implications of regional differences in diets around the world. Changes in dietary composition between 1961 and 2018 were reviewed. Comparable regional diets were envisaged by adjusting existing local food preferences to a daily consumption of 3,500 kcal/cap/day, of which 30% of the calories were considered to be from animal products. Our results show that the compositions of regional diets remained relatively stable from 1961 to 2018, particularly in consumption of animal products, and are not approaching homogeneity across regions. If future diets retain their present composition, the environmental impact may be up to 30% lower than the typical “low estimate” of an affluent diet from the literature (e.g., the Mediterranean diet), but in some cases higher than the “top estimate” of an affluent diet in the literature (e.g., the North American diet); driven mainly by the type of meat consumed. Diets differ in the relative magnitudes of their effects on individual environmental indicators. For example, one diet may cause less water use but more greenhouse gas emissions than another diet, so different strategies are required for the reduction of their environmental impacts. We conclude that pathways to reduce environmental impacts of the global food system should be designed in the context of regional differences in food consumption.

Appendices

Appendix 1

Countries included in each of the 19 regions analyzed in this paper. The regions are defined by the FAO. The first column indicates the FAO code for each country.

Appendix 2 Differences in dietary composition among regions in 1961 and in 2018

In this appendix, the detail matrix d_ij are shown for crop-based products and animal products in 1961 and in 2018. The values in these matrixes indicate the differences in dietary compositions among the regions. See Sect. 2 in the paper for detail on the calculations and interpretation of the results. Table 1 in the article show the last column of each matrix, the average values of each region with the rest of the regions. However, the complete matrixes show the detail comparison of each region with each region. Note that these are symmetrical matrixes.

Appendix 3 Detail description of the composition of animal products consumption in the diets of the regions studied in this paper

The following tables show the share of each animal product in the total animal products caloric supply per capita for each region by splitting up the specific food product of the “other animal-based” products considered in this paper. These are illustrated in Fig. 1 of the paper.

Appendix 4 Calculation of regional affluent diets in values of kilogram of food per person per year

The regional diets in units of kg/cap/yr for each region were calculated using the following equation:

$${RK}_{m}= \frac{{RC}_{m }* {K}_{m}}{{C}_{m}}$$

where $RK$ are the comparable regional diets in units of kg/cap/yr for every food category $m (\mathrm{Figure A}1); RC$ is the value of the comparable regional diet calculated in Fig. 2; $C$ and $K$ are the average values of food supply in the period of 2014–2018 (FAO, 2020b) in units of kcal/cap/day and in kg/cap/yr respectively. The data of $C$ are shown in Fig. 1a.

The values of Fig. 4 are shown in the Supplementary Information.

Appendix 5 Calculation of environmental impact of “other crop based” and “other animal based” products

The environmental impact of “other crop based” and “other animal-based” categories (Table 1) is calculated based on the values of the rest of the food categories, respectively for crop-based and animal-based products. To calculate it, each environmental impact is weighted by how much it is consumed so that the calculated environmental impact reflects the environmental pattern of the food composition of the diet. For example, if the crop-based food consumption is mainly wheat and maize, and the rest is “other crop-based” products, then the environmental impact of “other crop-based” products is the average of the environmental impact of wheat and maize. For this reason, the environmental impact of “other crop-based” and “other animal-based” products was done individually for each region because of the different compositions of the crop-based and animal-based products in the diets. The following equations describes the calculations of these values, and the results are shown in Table 4:

$${I}_{oc}= \frac{\sum_{c}{i}_{c}}{\sum_{c}{f}_{c}}$$

(3)

$${I}_{oa}= \frac{\sum_{a}{i}_{a}}{\sum_{a}{f}_{a}}$$

(4)

where ${I}_{oc}$ and ${I}_{oa}$ refers to each of the three types of environmental impact (land use, GHG emissions and water use for irrigation) of the “other crop-based products” and of the “other animal-based products” respectively for a certain region; $c$ refers to the crop-based food categories used (except “other crop-based”); $a$ refers to the animal-based food categories used (except “other animal-based”); $i$ refers to the environmental impact of $a$ or $c$ (Table 3); and $f$ refers to the amount consumed (kg/cap/yr) in each region for each food category.