Systematic review of US diets and sustainability
This systematic review looks at dietary patterns and food sustainability in the United States. It estimates that the healthy US-style diet recommended by the Dietary Guidelines for Americans is associated with similar or higher levels of greenhouse gas emissions, energy use and water use compared to the current US diet.
The review also finds that, among the healthy dietary patterns in the studies reviewed, those that are higher in plant-based foods are generally beneficial for environmental sustainability, primarily because of lower consumption of meat and dairy. The review notes that further research is needed on the water use associated with diets higher in plant-based foods.
For more on this topic, see also the FCRN’s detailed summary of the 2015 paper Energy use, blue water footprint, and greenhouse gas emissions for current food consumption patterns and dietary recommendations in the US, the blog post Further Attention to the Environmental Implications of Dietary Choices by Michelle Tom (the author of that paper) and a commentary by Mike Hamm.
Improving awareness and accessibility of healthy diets are key challenges for health professionals and policymakers alike. While the US government has been assessing and encouraging nutritious diets via the Dietary Guidelines for Americans (DGA) since 1980, the long-term sustainability, and thus availability, of those diets has received less attention. The 2015 Dietary Guidelines Advisory Committee (DGAC) examined the evidence on sustainable diets for the first time, but this topic was not included within the scope of work for the 2020 DGAC. The objective of this study was to systematically review the evidence on US dietary patterns and sustainability outcomes published from 2015 to 2019 replicating the 2015 DGAC methodology. The 22 studies meeting inclusion criteria reveal a rapid expansion of research on US dietary patterns and sustainability, including 8 studies comparing the sustainability of DGA-compliant dietary patterns with current US diets. Our results challenge prior findings that diets adhering to national dietary guidelines are more sustainable than current average diets and indicate that the Healthy US-style dietary pattern recommended by the DGA may lead to similar or increased greenhouse gas emissions, energy use, and water use compared with the current US diet. However, consistent with previous research, studies meeting inclusion criteria generally support the conclusion that, among healthy dietary patterns, those higher in plant-based foods and lower in animal-based foods would be beneficial for environmental sustainability. Additional research is needed to further evaluate ways to improve food system sustainability through both dietary shifts and agricultural practices in the United States.
Reinhardt, S.L., Boehm, R., Blackstone, N.T., El-Abbadi, N.H., McNally Brandow, J.S., Taylor, S.F. and DeLonge, M.S., 2020. Systematic Review of Dietary Patterns and Sustainability in the United States. Advances in Nutrition, Published online ahead of print.
North America is the northern subcontinent of the Americas covering about 16.5% of the Earth's land area. This large continent has a range of climates spanning Greenland’s permanent ice sheet and the dry deserts of Arizona. Both Canada and the USA are major food producers and some of the largest food exporters in the world. Industrial farms are the norm in North America, with high yields relative to other regions and only 2% of the population involved in agriculture.