Diets are currently scientifically measured for the adequacy of nutrient intake, for health and/or prevention of chronic disease. Few published metrics attempt to account for the sustainability of diets.

In particular, the significance of ultraprocessing on the nature of food and the state of human and planetary health is understated.

‘We face two massive challenges that are intertwined – unprecedented pandemics of obesity and chronic disease, and environmental degradation. We need to promote healthy, sustainable diets to help deal with these issues,’ Dr Machado said.

She said the existing metrics were insufficient to tackle the complexity of these problems because they didn’t consider important aspects such as the role of food processing. For example, ultra-processed foods already dominate diets globally, but no existing metric captures the intake of these foods. As such, she is identifying indicators of a global sustainable healthy diet based on the degree of food processing.

For the first phase of the project, Dr Machado is conducting a scoping review to identify how indicators of a sustainable healthy diet are considered in global diet quality metrics published to date.

Based on the results of this review, she will survey national and international experts in nutritional epidemiology, environmental health, dietary assessment and food and nutrition policy, to determine the most important considerations for a healthy and sustainable diet quality metric.

Dr Machado will then develop a metric and assess the impact of this recommended diet on people’s health (e.g. body-mass-index, blood pressure) and environmental (greenhouse gas emissions, water and land use) outcomes.

She will use data from the National Nutrition and Physical Activity Survey (NNPAS) 2011-12, part of the Australian Health Survey 2011-13, to answer these questions.

‘I plan to develop a metric that is adaptable to different cultural and food systems scenarios, and that can be used to assess the impact of diets on both health and environmental sustainability outcomes,’ Dr Machado said.

‘Such a tool will be of immediate use to monitor the global performance and progress of populations’ diets against current sustainable healthy diet recommendations and towards the United Nations’ 2030 Sustainable Development Goals.

‘I hope my research will help governments to create policies that support people to achieve a diet that is good for both human and planetary health, and that people can be informed to make healthier and more sustainable food choices,’ she said.

Study findings:

Measuring Adherence to Sustainable Healthy Diets: A Scoping Review of Dietary Metrics