The role of energy cost in food choices for an Aboriginal population in northern Australia

Aboriginal Australians, compared with the general Australian population, have high rates of premature mortality from preventable chronic diseases.1 The association between higher morbidity and mortality rates from preventable chronic diseases and lower socioeconomic status is well established.2 In remote areas of the Northern Territory, just over half (52.7%) the Aboriginal and Torres Strait Islander people are in the lowest income quintile;3 government pensions and allowances are their main source of income.

Socioeconomic factors have a big impact on food and nutrient intakes and food purchasing patterns;4-6 material and economic constraints are recognised as key determinants of dietary intake.7 High-quality nutrition is known to protect against chronic diseases,8 but energy-dense, nutrient-poor foods cost much less than nutrient-rich foods.9,10 Applying incrementally increasing cost constraints to a typical French diet resulted in a diet high in refined carbohydrates and low in fresh meat, fruit and vegetables.11 These findings led to the “economics of food choice” theory — that people’s dietary decisions, when made within the context of sustained budgetary constraints, are driven by maximising energy value for money (dollars per megajoule [$/MJ]), resulting in energy-dense, nutrient-poor diets.12

To our knowledge, the energy cost of foods in relation to dietary patterns has not been examined for Australian Indigenous populations. Our study examined the relationship between dietary quality, energy density and energy cost of food in a remote Australian Aboriginal community, with the aim of explaining the persistent, poor dietary patterns reported for Indigenous populations over decades despite efforts to improve dietary quality.

Energy available through the community food supply on an estimated per person daily basis of 9.45 MJ was comparable with the estimated average daily requirement for this population of 9.42 MJ, and comparable with the 9.07 MJ daily requirement reported for the Australian population.18

Refined carbohydrates contributed disproportionately to total dietary energy availability; ie, four food items — table sugar (16%), flour (13%), bread (11%) and milk powder (8%) — provided about half the energy available through the community food supply. In contrast, fruit (excluding fruit juice) and vegetables contributed minimally to energy availability (1% and 5%, respectively).

As illustrated in Box 1, cereal and cereal products, sugar and confectionery, and fats and oils contributed most to dietary energy relative to dietary cost. In contrast, nutrient-dense foods, such as meat and meat products, fish and seafood, fruit and vegetables, contributed least energy relative to cost. Energy costs (in $/MJ) of a range of foods found in the community store are given in Box 2. Sugar, cooking oil, rice, margarine and white flour are the lowest-cost options, providing dietary energy at minimal cost (< 0.26 $/MJ), compared with fresh vegetables, meat and fruit, which provided energy at a much higher cost. Box 3 highlights the up-to-100-fold range in energy costs of foods in this community store.

The most important finding in our study was the marked gradient in cost per MJ between low-quality foods, rich in refined carbohydrates and fats, and the high-quality, nutrient-dense foods recommended in the Australian guide to healthy eating,19 illustrating the inverse relationship between energy density and energy cost, consistent with published data.

The dietary pattern we found — low intake of fruit and vegetables and high intake of refined carbohydrates — is consistent with that reported for economically marginalised groups in Australia and other affluent Western societies. Although foods such as meat, fruit and vegetables provide more nutrients per dollar spent, there is good evidence that, with sustained budgetary constraints, quality is compromised before quantity, with consumers maximising calories for dollars spent.

The results of our study highlight the importance of modelling the food supply available to Indigenous people in remote areas to identify practical modifications that can be achieved at minimum cost. Achieving nutritional recommendations at minimum cost, however, is a challenge, as often taste and convenience are compromised,20 and the resulting diet is markedly changed from the typical diet, with much less fresh produce.21 On the basis of self-selected diets, it has been shown that, under normal circumstances, high-quality diets cost more.22

A primary motive for our study was to better understand why the poor-quality dietary patterns of remote Indigenous communities23 have changed little over more than two decades. This dietary pattern has been attributed to conservative food preferences resulting from the historical government policy, from the time of early European settlement through to the early 1970s, of providing rations for Indigenous Australians.24 This pattern is reinforced by contemporary issues of limited availability of healthy food choices, high food costs and limited household-storage and food-preparation capacity.25

Our study shows that low income is a powerful driver of food choice — a factor compounded in remote communities by high costs of perishable foods, such as meat, fruit and vegetables.26 Our study focuses on one large, remote community, but similar socioeconomic conditions and disparities in food costs exist across all Indigenous communities in Australia.