Elsevier

Preventive Medicine

Volume 137, August 2020, 106124
Preventive Medicine

A three-dimensional dietary index (nutritional quality, environment and price) and reduced mortality: The “Seguimiento Universidad de Navarra” cohort

https://doi.org/10.1016/j.ypmed.2020.106124Get rights and content

Highlights

  • The Sustainable Diet Index considers nutritional quality, environmental impact and cost.

  • This index is associated with all-cause and cardiovascular mortality.

  • First index considering overall sustainable diet been associated with mortality.

  • Beans and potatoes positively correlate with the index.

  • Red meat negatively correlates with the index.

Abstract

Several healthy diet indices have been associated with mortality risk. However, the ideal diet should not only be healthy but also environmentally friendly and affordable. The study aimed to determine if a new Sustainable Diet Index (SDI), which takes into account the nutritional quality, environmental impacts and market price of diets, was associated with all-cause and cause-specific mortality. Using data from the “Seguimiento Universidad de Navarra” Project, a prospective cohort study of Spanish university graduates, the study included 15,492 participants who were recruited between December 1999 and March 2014 and followed-up for a median of 10 years. Cox regression was used to determine the relationship of SDI and its components with all-cause and cause-specific mortality risk. Hazard ratios with adjustment for several confounders were calculated. The weights for the foods contributing to the SDI were assessed with multiple regression analyses and variability with nested regression analyses. The highest quartile of the SDI scores was associated with a 59% relative reduction in all-cause mortality (HR 0.41, 95% CI 0.23–0.75; ptrend < 0.001) and 79% reduction in cardiovascular mortality (HR 0.21, 95% CI 0.05–0.85; ptrend < 0.001). SDI was positively correlated with beans and potato consumption but negatively correlated with red meat intake. Red and processed meats, fatty dairy products and fish consumption accounted for most of the variability in the SDI. Altogether, dietary patterns accounting not only for nutritional quality of the food but also the impact on the environment and affordability could still provide health benefits.

Introduction

Non-communicable diseases (NCD) are the main causes of death in developed countries (IHME, n.d.). Changes in lifestyles, especially diet, could play an essential role in preventing NCD and premature mortality (World Health Organization. Diet, 2003; Muller et al., 2016). Several investigations have shown that some high-quality dietary patterns, mainly plant-based, have an inverse relationship with total mortality (Kant et al., 2004; Serra-Majem et al., 2009; Martinez-Gonzalez et al., 2014; Martinez-Gonzalez et al., 2015; Atkins et al., 2016; Li et al., 2015). Traditionally, the nutritional quality of diets was the only concern when recommending a pattern. Although necessary, assessing the nutrient content of diets is no longer sufficient. The food system itself is one of the main drivers of environmental degradation. It is related to approximately 25% of the total anthropogenic greenhouse gas (GHG) emissions (IPCC, 2014), in addition to nutrient pollution (Vitousek et al., 1997). It is also responsible for the extensive use of natural resources, accounting for 70% of fresh water use (A Comprehensive Assessment of Water Management in Agriculture, 2007) and 40% of the Earth's land (FAO, n.d.).

In recent years, the term sustainable diet emerged, (Burlingame and Dernini, 2010) emphasizing that an ideal dietary pattern should not only be healthy, but at the same time environmentally-friendly and economically affordable. Recent publications from different scientific bodies indicate an increasing impetus towards global action to achieve human health within the context of sustainable food systems (Willett et al., 2019; Rose et al., 2019; Tagtow et al., 2014). A general adoption of plant-based diets could lead to benefits not only for people but also for planetary health (Hemler and Hu, 2019; Springmann et al., 2016). As market price is one of the main drivers for food choices, the affordability of recommended dietary patterns is a main consideration (Darmon and Drewnowski, 2015; Drewnowski and Darmon, 2005).

Reductions in mortality risk have been demonstrated with higher scores in dietary indices (Schwingshackl and Hoffmann, 2015; Harmon et al., 2015; Knoops et al., 2006; Mitrou et al., 2007). To date, the development of a priori dietary indices have been mostly done for the purpose of assessing only their health-associated benefits, usually leaving out all aspects related to the impact on the environment and/or affordability. A holistic look at diet is necessary; thus, new indices are being developed to consider all aspects or dimensions of sustainability (Seconda et al., 2019a). The aim of our study was to develop and evaluate whether a proposed “Sustainable Diet Index (SDI)”, which considers different aspects of the diet from a holistic point of view by combining the nutritional quality, environmental impact, and economic aspects, is associated with all-cause and cause-specific mortality in a prospective cohort in Spain. We also evaluated the association of each of the sub-indices (i.e. nutritional quality, environmental impact index and market price). In addition, we compared the SDI with the index only focused on the nutritional quality (i.e. the 2015–2020 Dietary Guidelines for Americans Index (2015DGAI)) in terms of environmental impact and cost.

Section snippets

Study population

The Seguimiento Universidad de Navarra (University of Navarra Follow-up) (SUN) project is an ongoing and multipurpose Spanish cohort composed of university graduates (Carlos et al., 2018). These graduates were informed about the study objective, methodology, data management, and their right to drop out of the study without repercussions. Voluntary completion of the baseline questionnaire was considered as giving consent to be part of the study. The SUN project started in 1999 and follow-up data

Results

The current study included a total of 15,492 participants (6082 men and 9410 women), and 166 deaths were identified during the follow-up period (155,852 person-years), with a median follow-up of 10.35 years. The baseline characteristics of participants across quartiles of SDI are presented in Table 1. Participants in the highest quartile of the SDI (Q4) compared to those with the poorest score (Q1) tended to have higher scores in the nutritional quality index, and lower for the environmental

Discussion

The current paper presents a new dietary index, the Sustainable Diet Index, to evaluate several dimensions of a dietary pattern simultaneously. The novelty of this index is that it looks at diet from a holistic point of view by not only assessing its nutritional quality but also considering its environmental sustainability and market price. Higher scores in this index were associated with lower mortality risk, especially cardiovascular mortality. Beans and potatoes were the most sustainable

Conclusions

The Sustainable Diet Index is associated with all-cause, and cause-specific cardiovascular, mortality risk in a longitudinal analysis on a well-known cohort. The major strength of this new index is that it assesses diet quality in a holistic sense, taking into account not only its nutritional quality but also its environmental impact and its economic affordability. Nevertheless, further investigations should be carried out to confirm in other populations the relationships between SDI and other

CRediT authorship contribution statement

Ujué Fresán:Conceptualization, Methodology, Formal analysis, Investigation, Writing - original draft, Writing - review & editing.Miguel A. Martínez-González:Writing - review & editing, Funding acquisition.Gina Segovia-Siapco:Writing - review & editing.Joan Sabaté:Writing - review & editing.Maira Bes-Rastrollo:Conceptualization, Methodology, Writing - review & editing, Supervision, Funding acquisition.

Acknowledgments

We would like to thank the participants of the SUN cohort for their continuous involvement in the project and all members of the SUN study for their support and collaboration.

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