A new review maps the growing toolbox used to assess food and diet on both nutritional and environmental impacts, but shows that inconsistent methods still stand in the way of a clear standard.
Food-based indices for assessing the nutritive value and environmental impact of food and diet: a systematic review.. Image Credit: PeopleImages/Shutterstock
In a recent study published in the journal one moreThe researchers examined food-based indices that classify or rank foods and diets based on environmental impact and nutritional value.
Food labeling is widely used to influence consumption practices by providing product information to consumers. While nutrition labeling is mandatory and regulated in the United Kingdom (UK), there has been considerable interest in integrating sustainability information into labeling. This reflects growing awareness of the role of the food system in resource depletion, climate change and biodiversity loss.
Sustainability is a broad concept with multiple dimensions, including cultural acceptability and affordability, which can lead to inconsistencies in application. Focusing specifically on environmental impact and nutritional value can help reduce consumer misconceptions and improve understanding of environmentally responsible and healthy dietary choices.
about the study
In this study, researchers examined food-based indices that assess environmental impact and nutritional value to classify or rank diets and foods. These indices were called nutrient and environmental combined indices (NECI).
Six bibliographic databases were searched for relevant original studies published between January 2009 and August 2025. Reviews were excluded, although their reference lists were examined for additional studies.
Eligible studies assessed both the environmental impact and the nutritional value of the diet or food. Studies focusing only on one aspect or individual foods were excluded. Broader sustainability dimensions including socio-cultural and economic factors were also considered.
Relevant data including study characteristics, methodological details and public health objectives were extracted. Replication was used as a quality assessment metric, defined as the transparency and reproducibility of the NECI methodology. The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (Prisma) 2020 guidelines and was conducted by two independent reviewers. The protocol was registered in the International Prospective Register of Systematic Reviews (Prospero).
conclusion
13,634 records were identified from database searches, and an additional 9 were identified through reference screening. After deduplication and screening, 25 studies describing 27 methodological approaches for 25 NECIs were included.
Two studies presented the same index with two scoring methods, while others presented a single index. Nine NECIs were designed for diet, six for food, and 10 for both.
The twelve NECIs incorporated additional sustainability dimensions beyond environmental impact and nutrition, most commonly economic and socio-cultural factors. Fifteen NECIs were developed by individual institutions, while 10 were developed through collaborations, primarily involving universities and research institutes.
Most NECIs (24) targeted adults, and one addressed the general population. Seventeen were developed for the European population. Nutritional scoring typically uses variations of the nutrient-rich diet score, usually calculated based on mass, although some use energy-based metrics.
Nutritional scoring relies on individual nutrients in most approaches, with less use of food groups or combined methods. Life cycle assessment was the most common method for environmental scoring, usually based on the amount of food consumed.
Substantial variation was observed in scoring methods, functional units, system limitations, weighting approaches, ranking criteria, and presentation formats. Some NECIs used a single integrated score, while others presented environmental and nutrition scores separately, limiting direct comparability.
Twenty-one NECIs were considered replicable, one possibly replicable, and one non-replicable. Major public health applications include policy development, research, decision support, dietary guideline development, and consumer education.
conclusion
The study identified 25 indices that assess both the environmental impact and nutritional value of diet and food. The findings highlight considerable methodological diversity across NECIs, underscoring the need for harmonized criteria.
Standardizing these indices could support more consistent comparisons and improve their utility for public health decision making, ultimately helping to promote environmentally sustainable and healthy dietary choices.
