Guidelines Dietary - Eat For Health

G3Complexities of measuring the sustainability of the food supplyHistorically, dietary guidance has been based on experimental evidence from nutritional science and epidemiology,with sustainability often referred to in the context of ‘triple bottom line’ considerations of economic, social andenvironmental factors. 1058 Understanding the environmental implications of food choices involves consideringnew, often non-empirical evidence drawn from assessment of the relationship between the food system, foodchoices and environmental outcomes. This requires evidence from research in environmental science, agriculturalscience and economics. Government reports are also useful, especially in areas with policy implications, such ascarbon accounting.The food system comprises many stages from inputs on-farm to waste management following consumer use.As shown in Figure G1, these include agriculture and aquaculture, processing, manufacturing, transport, retail,preparation, consumption and waste management. The complexity of the system challenges the developmentof standardised methodologies for measuring the environmental consequences of producing particular foods. 1060As well, some current analyses do not consider the process through to the consumer and the subsequentdisposal of waste.The environmental consequences of food production depend on the agricultural system used and the particularenvironmental aspect examined, as these differ in impact, with implications for yield, quality and affordability. 1042Given this, the consequences cannot be assessed solely on a commodity basis but are dependent on whereand how the product is grown. For example, it is estimated that in NSW, the amount of water used in beef cattleproduction ranges broadly from 3.3 L to 221 L H2Oe kg −1 live weight at farm gate. 1061 As well, it is importantto ensure that focussing on one outcome (e.g. emissions) does not have an unfavourable effect on another(e.g. soil degradation) and consequently add further pressure to the food system.New technologies will play an important role in developing sustainable food systems, but the extent dependson consumer acceptance and economic constraints. 1040 There is a need for more Australian data on manycomponents of the food system and further research and development is required.Two methodologies – process life cycle analysis (Process-LCA) and input-output analysis – are increasinglyused to critically analyse the environmental impact of various components of the food system:• Process-LCA considers the environmental impact of all processes involved in bringing a product to theconsumer, including the way it is used and the impact of disposing packaging and waste. LCA methodologiesare highly standardised, however the complexity of analysing sustainability at the food supply level means thatmany different questions are asked and models used which can limit meaningful comparisons. 1060 Additionally,to obtain an overall perspective, the same process must be completed across the entire life cycle. LCAmethodologies are complex, time consuming and expensive, which inhibits their use for data collection.• Input-output modelling is a useful tool for assessing the environmental impact of consumption. It was originallydeveloped for economic analysis, but has been applied to environmental analysis since the late 1960s.It can be used to assess environmental indicators such as land disturbance, water and energy use, and totalindicator intensities (the total amount of an indicator required to produce and deliver a value unit of a particularcommodity). 1062 This can be used in decision making to predict and forecast the impact of future performanceof an economy and the effect of changes to relevant systems.In developing an evidence-base for sustainable food choices, different methodological approaches limit thecomparability of findings. For example, scope and definitions vary according to the stage of the food system beingconsidered. Some studies incorporate the environmental impact of manufacturing on-farm machinery and theproduction of all other on-farm inputs such as fertiliser, while others include only fertiliser production. Much of theenvironmental impact evidence for specific foods is based on primary production and on-farm effects, with lessinformation on aspects of the food supply chain such as processing, distribution, retail, consumption and wastemanagement. However, the environmental impact of the life cycle of a particular food cannot be considered only asa characteristic of the food, but of all the specific and local aspects of its production, movement, storage, preparationand ultimate fate.While overseas studies are not always generalisable to the Australian context, the body of Australian evidenceis steadily growing, and the interest in this field may serve to stimulate more research. Despite the abovechallenges, enough evidence exists to suggest pragmatic guiding principles on how dietary patterns and homepractices can contribute to reducing the environmental consequences of the food system.AppendicesNational Health and Medical Research Council133