Examination of the interrelationships between nutrition, environmental sustainability and food-processing: A concept study using model diets.

Recent work has focused on understanding the link between diet quality and environmental impact, however it is also important to consider the role food processing plays in this relationship. Using model meal plans, this paper examines the link between nutrient content, environmental impact, and processing. Four distinct meal plans were considered - 'Healthy', 'Unhealthy', 'Healthy (plant-based)', 'Healthy (plant-based, processed)'. For each a variety of environmental impact, processing and nutritional composition metrics were compared. Alternative healthy eating index (AHEI) score for the Unhealthy diet was significantly lower than the other three diets. The 'Healthy (plant-based)' diet had the highest AHEI score but was not significantly different to the 'Healthy (plant-based, processed)' and 'Healthy' diet scores. The greenhouse gas emissions for the two plant based diets were not significantly different to each other or to the 'Healthy' diet but were significantly lower than the 'Unhealthy' diet. The 'Healthy', 'Unhealthy', and 'Healthy (plant-based)' diets had similar processing specific energy consumption values however, the 'Healthy (plant-based, processed)' diets had significantly greater specific energy consumption. There was no clear link between diet quality and food processing when considered using processing specific energy value. When the number of processes in each diet was estimated, the unhealthier diet had considerably more processes associated with it. Examining the interaction of nutritional quality, environmental impact and processing of diets in this way highlights the complexity of the inter-relationships. Understanding these interactions is necessary to support the transition to healthy diets from sustainable sources.