It mostly depends on your starting point. If you’re desperately poor and most of your meagre income goes on food (including grains), and you barely have enough to eat, then when your income increases you simply eat more of the same in order to better satisfy your basic needs. But if your income is already sufficiently high that your basic nutritional needs are met, what then happens to your grain consumption if you become even richer?
This chart helps answer that question. The chart traces dietary change in different regions of the world from 1961 to 2011. In all regions real incomes improved over the period. In a high income country such as the United States, calorie intake (including calories from cereal grains and starchy roots) increased as incomes rose. However the proportion of all calories coming from cereals and starchy roots plateaued throughout the period. Staples like cereal grains remained an important but nonetheless minor direct component of the USA diet.
Source: W.A. Masters (2016) Assessment of Current Diets: Recent Trends by Income and Region, Working Paper No. 4, Friedman School of Nutrition Science and Policy, Tufts University. See www.nutrition.tufts.edu/profile/william-masters
By contrast, in Africa, despite their increase in real incomes, by the end of 2011 their per capita calorie intake was substantially less than the USA’s per capita calorie intake in 1961. Diets in Africa throughout the period 1961 to 2011 remained greatly directly dependent on cereals and starchy roots. About 65% of the African per capita calorie intake directly came from cereal grains and starch roots.
A further contrast is East Asia which illustrates how a large increase in real income can be associated with marked dietary change. Remarkable economic growth in East Asia over the last few decades has helped double its per capita calorie intake, the greatest increase among all regions. In addition, the makeup of the East Asian diet changed markedly. Cereal grains and starchy roots formed a much reduced share of calorific intake as real incomes substantially increased. In the 1960s and 1970s around ¾ of the calorific intake came from direct consumption of cereal grains (mostly rice and wheat), yet in subsequent decades, as growth in real incomes increased, more of the dietary energy came from non-staples (e.g. meats and dairy products). Eventually only about half of the per capita calorie intake directly came from cereal grains and starch roots.
But wait….there is more to say about how grain consumption is affected by income change. The following table draws on a 2013 dataset of food consumption in 180 countries. Countries are divided into quintiles of per capita GDP (36 countries in each quintile). As income levels increase then more fruit, milk, red meat and processed meat are consumed and less fibre is consumed. Whole grain consumption diminishes, except when incomes are in the highest category. In general, as incomes increase then whole grains form a diminishing share of diet by weight and calorie intake. Also, apart from the situation when incomes are at their highest, whole grain consumption (grams per capita per day) declines as incomes increase.
Source: Extracted from W.A. Masters (2016) Assessment of Current Diets: Recent Trends by Income and Region, Working Paper No. 4, Friedman School of Nutrition Science and Policy, Tufts University. See www.nutrition.tufts.edu/profile/william-masters
It is important to note, however, that grains are not only consumed as whole grains but are also indirectly consumed as key ingredients in the production of other foodstuffs such as red meat and processed meat. Meat production often depends on feed grains. To produce one kilogram of meat from chickens, pigs, lambs and beef cattle often takes 2, 2, 4 and 6 kilograms of feed grain respectively. Hence, although whole grain consumption mostly diminishes as incomes increase, nonetheless the increased consumption of red meat and processed meat means that consumers increase their indirect dependence on grains, especially feed grains. Hence, as incomes increase there is a change in the composition of grains demanded by consumers, with a shift towards greater indirect dependence on feed grains.