Development and evaluation of a multidimensional diet quality score for sustainable healthy diets (SUSDIET)

The Food and Agriculture Organization of the United Nations and the World Health Organization recommend reducing the intake of ultra-processed foods whilst promoting diets rich in diverse plant foods and with appropriate amounts of animal products. Yet no existing metric simultaneously captures these dimensions of sustainable healthy diets. This study aimed to develop and evaluate a multidimensional diet quality score for sustainable healthy diets (SUSDIET). Consensus from experts on procedures to establish an operational definition for a global sustainable healthy diet were used for the development of SUSDIET. Data on adults (≥19 years, n = 5000) from the Australian National Nutrition and Physical Activity Survey 2011-12 were used to evaluate SUSDIET. Mean scores of the SUSDIET were analysed according to participants characteristics. Regression models were used to assess the associations between SUSDIET and intake of nutrients and cardiometabolic health outcomes (indicators of adiposity and hypertension). We developed SUSDIET, a food-based diet quality score incorporating variety of plant foods (12 food groups), intake of animal products (5 food groups), and ultra-processed foods (1 food group). SUSDIET overall score ranges from 0 to 15, with a higher score indicating a more healthy and sustainable diet. Among Australian adults, SUSDIET overall score was 5.83 ± 0.03 (range 0.21-10.80), and was associated with a healthier nutrient profile and lower odds of obesity and abdominal obesity. SUSDIET will support research aiming to assess the impact of diets on both health and environmental sustainability outcomes among the general adult population and inform diet monitoring globally.