Climate change mitigation through dietary change: a systematic review of empirical and modelling studies on the environmental footprints and health effects of ‘sustainable diets’

Abstract

The adoption of healthy diets with low environmental impact has been widely promoted as an important climate change mitigation strategy. Typically, these diets are high in plant-sourced and low in animal-sourced and processed foods. Despite the fact that their environmental impacts vary, they are often referred to as ‘sustainable diets’. Here we systematically review the available published evidence on the effect of ‘sustainable diets’ on environmental footprints and human health. Eight databases (OvidSP-Medline, OvidSP-Embase, EBSCO-GreenFILE, Web of Science Core Collection, Scopus, OvidSP-CAB-Abstracts, OvidSP-AGRIS, and OvidSP-Global Health) were searched to identify literature (published 1999–2019) reporting health effects and environmental footprints of ‘sustainable diets’. Available evidence was mapped and pooled analysis was conducted by unique combinations of diet pattern, health and environmental outcome. Eighteen studies (412 measurements) met our inclusion criteria, distinguishing twelve non-mutually exclusive sustainable diet patterns, six environmental outcomes, and seven health outcomes. In 87% of measurements (n = 151) positive health outcomes were reported from ‘sustainable diets’ (average relative health improvement: 4.09% [95% CI −0.10–8.29]) when comparing ‘sustainable diets’ to current/baseline consumption patterns. Greenhouse gas emissions associated with ‘sustainable diets’ were on average 25.8%[95%CI −27.0 to −14.6] lower than current/baseline consumption patterns, with vegan diets reporting the largest reduction in GHG-emissions (−70.3% [95% CI: −90.2 to −50.4]), however, water use was frequently reported to be higher than current/baseline diets. Multiple benefits for both health and the environment were reported in the majority (n = 315[76%]) of measurements. We identified consistent evidence of both positive health effects and reduced environmental footprints accruing from ‘sustainable diets’. The notable exception of increased water use associated with ‘sustainable diets’ identifies that co-benefits are not universal and some trade-offs are likely. When carefully designed, evidence-based, and adapted to contextual factors, dietary change could play a pivotal role in climate change mitigation, sustainable food systems, and future population health.

The role of plant-based alternative foods in sustainable and healthy food systems: Consumption trends in the UK

“…There are many leverage points across the food system (from farm to waste) that could bring about transformational change, but it appears unlikely that the agricultural sector will be able to meet global climate targets without concurrent substantial dietary change on the consumer side ( Theurl et al, 2020 ). A global transition to “sustainable diets” is being widely promoted; diets typically high in plant-based and wholefoods, and low in animal sourced foods which will have co-benefits for human health and environmental sustainability ( Willett et al, 2019 ; Springmann et al, 2016 ; Jarmul et al, 2020 ). As there is much geographic and cultural variation in diets and agricultural practices, pathways of dietary transition will vary at the national and local level ( HLPE, 2017 ).…”

Eat Well to Fight Obesity… and Save Water: The Water Footprint of Different Diets and Caloric Intake and Its Relationship With Adiposity

“…Despite the idea of healthy eating as a means of reducing the environmental impact of diets has been widely disseminated ( 20 , 85 ), these effects can vary greatly in the regard of environmental impact and water use specifically, and, aside from what has been referred to, healthy diets could generate a higher impact and WF than other types of diets ( 86 ). Although following dietary recommendations are one of the most common ways of promoting healthy and sustainable eating, for some countries, this does not support environmental impact reduction.…”

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

“…The relevance of the categorization (into 4 types of approaches) suggested in the present article has been assessed by testing the classifiability of more than 50 studies identified in 2 recent systematic reviews on sustainable diets. 11 , 12 A large majority of the studies could be classified within the 4 classes.…”