Sustainable diets: Good for us, good for the planetSymposium Presentation
With the food system now recognized as a major source of environmental impact, many individuals are seeking information about sustainable food choices and eating patterns. The term sustainable diet has become popularized, although the term sustainable healthy diet would be preferred as it acknowledges the importance of starting from a health perspective. Diets with improved environmental profiles should not be recommended if they are nutritionally deficient.
Although the interactions between nutrition and environment are complex, health professionals and dietitians can safely make a variety of common-sense recommendations to support both health and the environment. These recommendations include:
- reducing over-consumption
- maintaining a healthy weight
- limiting consumption of nutrient-poor foods
- reducing food waste, and
- conserving water and energy in the kitchen.
While there is a lot of information in the popular and academic literature, it is difficult to reliably go further at the present time. The reasons are many, including:
- evidence based on poor environmental metrics
- failure to recognize that variations in the environmental footprint within a food category can often exceed variations between food categories
- failure to assess the multiple relevant environmental effects and evaluate trade-offs between environmental impact categories, and
- social and ethical considerations.
When data from national dietary surveys are assessed, it is found that high nutritional quality is not necessarily associated with low greenhouse gas (GHG) emissions. In addition, when theoretical diets with low GHG emission are modelled, they frequently present nutritional challenges and may not be realistic and/or acceptable to many individuals. There are also unknown health consequences and risks for individuals responding to environmental messaging about food. Fortunately, evidence emerging from Australia, France and elsewhere suggests that emphasizing national dietary guidelines is consistent with reducing GHG emissions.
Compared to the average Australian diet (which is below the suggested dietary targets for fibre, vitamin A, folate, calcium and magnesium), a diet that follows the Australian dietary guidelines, including a variety of protein sources, has been shown to be both nutritionally adequate and 25% lower in terms of GHG emissions. The key food differences between average intakes and recommendations are the need to eat more fruits, vegetables, legumes and dairy.
Another suggestion would be to emphasize the choice of products which have better environmental performance relative to others in the same food group (e.g., seafood from sustainable sources). However, it is recognized that there is currently a general lack of information at the product level available to consumers to make such choices possible.
Finally, it is important to recognize that sustainable healthy diets present a complicated multidimensional problem; we don’t yet have all the answers and there is no one-size fits all solution.