Sustainable diets here, should also consider better environments there
Perrine Laroche, a PhD student in the Environmental Geography group at VU Amsterdam, has won the 2020 Alpro Foundation Award for best publication with her research on the global impact of dietary shifts in the Western world.
Her detailed research reviews and locates the possible environmental impacts of different US diets by identifying domestic and outsourced foods. While numerous reports consider environmental benefits from reduced animal-based food production, there are fewer examinations of possible environmental pressures from increased demands of other alternative foods on eg land use and ecological change elsewhere.
Animal proteins provide about 29% of calories in current Western diets, but their production is relatively inefficient compared to the production of plant protein foods. Livestock requires feed, taking more land and water, and produces environmentally adverse outputs of methane and nitrogen. In 2019, an important and influential report (EAT-Lancet Commission) considered the balance of population health and environmental limits to global food production. They proposed a Global Planetary Health diet providing only 12% of calories from animal proteins (less than half current typical Western diets), and recommended diets with greater amounts of cereals, vegetables, legumes and nuts.
Perrine states that “Global benefits of dietary changes should not be realised at the expense of local environmental contexts.”
In the research by Perrine Laroche and colleagues, calculations to define food demands are based on US dietary survey data spanning average American diets, reported vegetarian and vegan diets, and the model EAT diet, all adjusted to provide 2500kcals per day. From the dietary data, land footprints to produce food or feed, or grassland resources are assessed (both US/domestic and outsourced). Further, environmental impacts linked to freshwater ecosystems, dependence on pollinators and nitrogen fixation are calculated.
The total land footprint is highest for the current Average American Diet (AAD), at 5161m2 per person per year and lowest for vegan diets at 1057m2. Most of this is due to much larger areas of grassland needed for meat-rich diets; grass provides 64% and 28% respectively of total feed for US beef and dairy (the remaining coming from concentrate crops such as soya, corn and wheat). However, demand for land for food and feed production varies across different diets.
Land outsourced (outside the USA) to provide foods consumed in the US is greatest for meat-rich diets, and is due mainly to imported beef, milk and feed. Outsourced foods higher in vegan and vegetarian diets such as cashew nuts, avocados, olives and oranges, may be dependent on pollinator friendly environments, and may contribute also to specific pressures for freshwater in dry areas.
Changes to US diets from meat-rich to low-meat will lead to lower land footprints both nationally and abroad, but replacement foods may increase pollinator dependency and pressures on freshwater in certain areas. The scientific advisory board of Alpro Foundation awarded this publication because this research takes into account the global impact of local shifts towards more plant-based eating patterns. Indeed it is important to be conscious that “Sustainable diets should be built on sustainable sourcing.”
Sustainable diets won’t come without trade-offs. Trade agreements are key to uplift individual efforts to adopt sustainable diets. Global benefits of dietary changes should not be realised at the expense of local environmental contexts. Reduced land requirements linked to lower consumption of animal proteins should allow more land for less intensive regenerative farming systems for plant proteins. Replacing animal proteins by protein from legumes might enable reducing use of chemical fertilizers.
Perrine Laroche was interviewed by leading nutrition writer Ursula Arens. This interview is available on demand at https://mynutriweb.com/diet-change-the-impact-on-agriculture-ecological-conditions/