Advantages and limitations of the methodological approaches used to study dietary shifts towards improved nutrition and sustainability

Abstract

Acting on diet is one of the changes required -in combination with actions on food production, transformation, and waste -to address the challenges of reducing the environmental impact of our food systems and eliminating all forms of malnutrition. The number of studies exploring how to move towards a more sustainable diet has exploded over the past decades, but there is a need to facilitate their understanding and use by policy makers and all other stakeholders possibly influencing diet sustainability. The aim of the present article is to propose a categorization of studies into 4 approaches, based on the type of methodology used to explore diet sustainability, and to highlight the principles, advantages, and limitations of each approach in order to help study users in their interpretation. The 4 approaches are: assessment of sustainability characteristics of hypothetical diets (approach 1) or existing diets (approach 2), identification of existing "positive deviants" (approach 3), and design of more sustainable diets with constrained optimization (approach 4). Specificities and key findings drawn from each approach are described, and challenges for future studies are discussed.

The nutrition and immunity (nutrIMM) study: protocol for a non-randomized, four-arm parallel-group, controlled feeding trial investigating immune function in obesity and type 2 diabetes

“…However, the limitations of dietary clinical trials include limited generalizability to larger populations or diverse demographic groups and the inability to accurately reflect real-world dietary patterns that can vary on a daily basis ( 92 ). Feeding studies also have a limited application in long-term follow-up to assess the effects of dietary interventions on chronic disease risk or other long-term health outcomes ( 93 ).…”

Consumer attitudes and behaviors toward more sustainable diets: a scoping review

“…The absence of human health from the layperson’s understanding of the term sustainable diets led to the Food and Agricultural Organization and World Health Organization to reaffirm the position of health as a core component of sustainable diets, by communicating sustainable healthy diet s in their 2019 Sustainable Healthy Diets: Guiding Principles report. 69 The literature explored here suggests that human health is now central to the idea of sustainable diets, both in research exploring the topic of sustainable diets 20 , 23 and in consumers’ conceptualization of what a sustainable diet is. These findings are echoed in a recent study highlighting the narrow focus on health and environmental indicators in research assessing the sustainability of diets.…”

The Alignment of Recommendations of Dietary Guidelines with Sustainability Aspects: Lessons Learned from Italy’s Example and Proposals for Future Development

“…Until now, we have not used optimization for the IDGs’ development, while the possibility of using the modeling methodology is not definitive or exempt from limitations. Optimization could be a suitable approach to guide the development of recommendations aimed at improving the sustainability of diets considering all of the characteristics of diets, to find solutions for nutritional, environmental, and economic aspects mitigating any possible incompatibilities among dimensions [ 53 ]. However, an important aspect that needs to be taken into account in the FBDGs’ development, is the cultural acceptability of foods as part of the sustainability of the diet.…”

“…As demonstrated in the abovementioned work on consumers’ acceptability in Italy of meat substitutes, a recommendation that includes an “exotic” meat alternative would be unlikely to be accepted, even if it were the best solution in terms of environmental impact [ 45 ]. As reported by Perignon and Darmon (2022), the identification of indicators for assessing the cultural acceptability and the availability of reliable data on these aspects are difficult and challenging [ 53 ].…”