Madam

We read with interest the recently published article by Payne et al. ⁽ Reference Payne, Scarborough and Cobiac ^{1 )} which addresses a subject of increasing importance to public health nutrition professions: dietary patterns with reduced greenhouse gas (GHG) emissions. Naturally, not all diets that are low in GHG emissions are also nutritionally adequate. Many discretionary foods, like soft drinks and biscuits, are in the lower range in terms of GHG-intensive foods⁽ Reference Drewnowski, Rehm and Martin ^{2 )}. Within society there can be found a matrix of diets with both higher and lower dietary quality as well as higher and lower GHG emissions.

As such, the critical question is how the GHG emissions of average diets compare with the GHG emissions of dietary patterns consistent with national dietary guidelines. Recommended diets are nutritionally complete and if they are also found to be lower in GHG emissions then there is a reinforcing environmental message that can be used to encourage adherence. In addition, if recommended diets can concurrently support both healthy eating and dietary GHG emissions reduction objectives, then the problems associated with multiple forms of public education about diets can be avoided.

We are therefore concerned that in the article by Payne et al. ⁽ Reference Payne, Scarborough and Cobiac ^{1 )} there has been a significant misinterpretation of research that has been conducted in Australia⁽ Reference Hendrie, Ridoutt and Wiedmann ^{3 )}. In Australia, the average adult diet is below the recommended target for dietary fibre, vitamin A, folate, calcium and a variety of other micronutrients. In large part, this is attributed to the excessive consumption of nutrient-poor discretionary foods and insufficient consumption of nutrient-dense core foods. In contrast, the national dietary guidelines^{( 4 )} are designed to meet dietary targets for all nutrients. Our modelling found that dietary patterns consistent with the Australian Dietary Guidelines had 25 % lower GHG emissions compared with the average adult diet⁽ Reference Hendrie, Ridoutt and Wiedmann ^{3 )}. Importantly, reducing discretionary foods alone is not a sufficient recommendation. Although this could achieve similar levels of reduction of dietary GHG emissions, such a diet is even further compromised with respect to micronutrient targets than the average diet. Payne et al. ⁽ Reference Payne, Scarborough and Cobiac ^{1 )} highlight this latter scenario, while missing the main point that in the Australian context, recommended diets are nutrient rich and have lower GHG emissions relative to the average.

On the one hand, we can concur with Payne et al. ⁽ Reference Payne, Scarborough and Cobiac ^{1 )} when they conclude that diets with lower GHG emissions may not result in improvements in nutritional quality or health outcomes. Indeed, there are a variety of dietary consequences and health risks that could result from individuals responding to environmental messaging about food. On the other hand, we question the sensibility of referring specifically to ‘Dietary recommendations for reduced GHGE…’⁽ Reference Payne, Scarborough and Cobiac ^{1 )}. Surely it is preferable to have coherent dietary guidance and avoid competing dietary recommendations that emphasise particular issues. According to the Australian evidence, recommended diets are not only nutritionally complete and culturally relevant, but also offer large dietary GHG emissions reduction benefits.