Between 1961 and 2021, the global average dietary energy available for human consumption increased by 35 percent, from 2 200 to 2 980 calories per person per day. Globally, during the same period, the share of staple foods available for human consumption declined from 57.4 percent to 48.4 percent, while the share of animal source foods grew from 12.2 percent to 15.1 percent and that of fats and oils increased from 8.4 to 12.7 percent (Figure 1.5). Yet, these changes have been largely uneven across countries, depending on different rates of income growth and the trends of other drivers of the nutrition transition. For example, nutrition experts analysing the relationship between income and dietary patterns in the 1990s suggested that it was mainly improvements in technology that resulted in the increased availability of inexpensive vegetable oils, which, together with income growth, have made high-fat diets accessible even to relatively low-income societies.42
FIGURE 1.5Total calories available for consumption in the world by food category, 1961–2021
SOURCE: Authors’ own elaboration based on FAO. 2024. FAOSTAT: Food Balances. [Accessed on 12 April 2024]. https://www.fao.org/faostat/en/#data/FBS. Licence: CC-BY-4.0.
Many researchers analyse the nutrition transition by assessing the size of the income elasticity of demand for different foods – an economic measure of how responsive the demand for food is to a change in income. A meta-analysis on income elasticities for food in Africa found that income elasticities for beverages, meat, fish, eggs and dairy are significantly higher than those for staple foods, confirming Bennet’s law and suggesting that, as income grows, the demand for animal source foods and processed products is more responsive than that for staple foods (see Part 4 for a discussion on different income elasticities according to the processing level of foods).43
Other studies explore the relationship between income and the composition of food consumption in the context of households exiting poverty and hunger. Economists suggest that the shift away from cheap sources of calories such as staple foods, and towards other foods that are relatively more expensive takes place immediately when income becomes sufficient to meet food subsistence needs.44
Using household data from the Sri Lankan 2016 Household Income and Expenditure Survey, a study suggests that an important factor in the shift away from staple foods is a subsistence threshold that reflects the extent to which the calories provided by a dietary pattern meet the energy needs of household members.g Below this threshold, poor people can experience hunger and adverse physical effects and will spend a large share of their additional income on relatively cheap, energy-dense staple foods, dedicating the smaller part to other foods. Above this subsistence threshold, income increases result in a progressive shift away from staple foods and increasing consumption of other relatively more expensive foods, including (ultra-) processed foods, that address aspirations for variety, taste, convenience, novelty and social status.45, h
Case studies: Mexico, Poland, the Republic of Korea and South Africa
Measuring the relationship between income and the composition of dietary patterns at the country level requires a long time series that contains information on the country’s economic growth and development trends. Using data from Mexico, Poland, the Republic of Korea and South Africa, covering the period 1961–2019, an analysis carried out for this report suggests a nonlinear (inverted U shape) relationship between the quantity of staple foods that is available for consumption per capita, measured in calories per day, and GDP per capita.i, 46
This inverted U shape is consistent with the studies on Bennet’s law that utilized household data and arises due to the subsistence threshold under (over) which income growth brings about increases (decreases) in the consumption of staple foods. However, the use of aggregate instead of household data means that the relationship can only be approximated for countries that had relatively low levels of income per capita at the outset and experienced economic growth, poverty reduction and a nutrition transition during the 1961–2019 period.j
For Mexico, where maize is a staple crop, the analysis indicates that increases in real GDP per capita from USD 4 270 in 1961, resulted in proportionally smaller increases in the calories available for consumption from staple foods. As the nutrition transition set in in the early 1980s, progressive GDP per capita growth (to USD 9 760 in 2021) was observed to be coupled with a significant decline in the calories available for consumption from staple foods (Figure 1.6). On average, between 1961 and 2021, the share of staple foods in total calories available for consumption declined from 57.9 to 41.7 percent, while that of animal source foods nearly doubled from 11.1 to 20.1 percent. Fats and oils also showed a significant increase in their share of total calories available for consumption from 7.1 percent in 1961 to 12.3 percent in 2021 (Figure 1.7). A study on Mexico’s nutrition transition, using data between 1984 and 1998, also showed that the progressive decline in cereal consumption was accompanied by a significant increase in soft drinks consumption in both rural and urban areas. Soft drink purchases increased by as much as 150 percent in Mexico City during this period.47
FIGURE 1.6Quantity of staple foods available for consumption (per capita, per day) and GROSS DOMESTIC PRODUCT per capita, 1961–2021
SOURCES: Authors’ own elaboration based on FAO. 2024. FAOSTAT: Food Balances. [Accessed on 15 February 2024]. https://www.fao.org/faostat/en/#data/FBS. Licence: CC-BY-4.0; World Bank. 2024. World Development Indicators: GDP per capita (constant 2015 US$). [Accessed on 15 February 2024]. https://data.worldbank.org/indicator/NY.GDP.PCAP.KD. Licence: CC-BY-4.0.
As in most Eastern European countries, Poland’s transition to a market economy in the early 1990s resulted in significant GDP per capita increases. GDP per capita increased more than threefold to USD 15 863 since 1991. The relationship between per capita calories available from staple foods and GDP per capita suggests a gradual decline in the daily calories available from staple foods per capita with increasing GDP (Figure 1.6). Poland’s nutrition transition was also facilitated by a higher diversity of foods available due to openness to trade.48 For example, between 1961 and 2021, the share of staple foods in total calories available for consumption declined from 54.8 to 33.6 percent, while the share of fruits and vegetables doubled from 2.4 to 4.9 percent (Figure 1.7).
FIGURE 1.7Mexico, Poland, the Republic of Korea and South Africa: Change in the composition of total food supply, 1961–2021
SOURCE: Authors’ own elaboration based on FAO. 2024. FAOSTAT: Food Balances. [Accessed on 12 April 2024]. https://www.fao.org/faostat/en/#data/FBS. Licence: CC-BY-4.0.
The nutrition transition in the Republic of Korea provides interesting insights as the country underwent a rapid structural transformation between the 1960s and 1990s, prior to the deepening of the globalization process that accelerated growth after the mid-1990s. With a rapid structural transformation and significant increases in real GDP per capita from USD 1 066 in 1961 to USD 32 786 in 2021, a progressive decline in the daily calories available from staple foods per capita, took place from the mid-1970s onwards (Figure 1.6). Overall, the share of staple foods in total calories available for consumption decreased dramatically from 86.4 percent in 1961 to 32.9 percent in 2021. The changes in the shares of animal source foods and fats and oils in the calories available for consumption were even more significant. During the 60-year period between 1961 and 2021, the share of animal source foods increased from 2.3 to 17.4 percent and that of fats and oils from 0.8 to 20.0 percent (Figure 1.7).
In South Africa, the relationship between per capita calories available from staple foods and GDP per capita also approximates an inverted U shape (Figure 1.6). Following its transition to democracy in 1994, South Africa’s economy experienced fast growth rates that sparked the nutrition transition. Nevertheless, South Africa has one of the highest inequality rates in the world and poverty is widespread, which together with well-rooted consumer preferences for maize, could potentially result in a relatively smaller shift away from staple foods. Indeed, the share of staple foods in total calories available for consumption declined from approximately 58.0 percent in 1960 to 44.6 percent in 2021, while that of fats and oils more than doubled from 7.1 to 16.3 percent (Figure 1.7).
