In a new study published in the Journal of Cleaner Production (Costa et al., 2023), researchers investigated the environmental consequences of two independent yet interconnected diet choices in a German context: (i) replacing dairy milk with soy milk, and (ii) replacing beef meatballs with pea protein balls. They related commodity demand to detailed agricultural rotations and land use changes via farm scale economic modelling coupled with a consequential life-cycle assessment (LCA).
The authors found that the substitution of beef meatballs with pea-derived protein balls resulted in GHG savings of 2.4 kg CO 2e per 100 g serving, and up to 7.3 kg CO 2e per 100 g serving if spared land is afforested. Environmental problems related to nutrient leakage such as eutrophication* and acidification** are also mitigated. Unless accompanied by dramatic reductions in beef consumption, the substitution of cow milk with a soy-based milk alternative does not lead to significant GHG mitigation owing to the displacement of dairy-beef production to less efficient suckler-beef systems. (Costa et al, 2023)
The authors concluded that, “This study confirms that legumes can play an important role in the realization of the EAT-Lancet [planetary health] diet and support considerable land sparing, livestock emission avoidance and synthetic fertilizer displacement, promoting not only GHG mitigation, but also mitigation of other environmental problems such as acidification.”** (Costa et al, 2023) Acidification slows the growth of fish and shellfish and can prevent shell formation in bivalve mollusks. This leads to a reduced catch for commercial and recreational fisheries, meaning smaller harvests and more expensive seafood. (NOAA, 2023)
The Eat-Lancet planetary health diet is a global reference diet for adults that is visually represented by half a plate of fruits, vegetables, and nuts. The other half consists of primarily whole grains, plant proteins (beans, lentils, pulses), unsaturated plant oils, modest amounts of meat and dairy, and some added sugars and starchy vegetables. (EAT Forum, 2019). See Figure 1 for visual representation of the Eat-Lancet planetary health diet.
Figure 1. Eat-Lancet planetary health diet plate
The Eat-Lancet planetary health diet is flexible and allows for adaptation to dietary needs, personal preferences, and cultural traditions. Vegetarian and vegan diets are two healthy options within the planetary health diet but are personal choices. (EAT Forum, 2019). High adherence to the EAT-Lancet planetary health diet has been associated with a lower risk of coronary events (Zhang et al., 2023), reduced risk of cancer and all-cause mortality (Karavasiloglou et al., 2023) as well as a lower risk for type 2 diabetes (Ojo et al., 2023).
In summary, Costa and co-authors (2023) argue that diet substitution should initially focus on replacing meat with plant-based alternatives, rather than dairy products, due to potential GHG gains and to avoid emissions “leakage” via displacement of (dairy) beef calf production to less efficient, dedicated beef systems. The reintroduction of legumes into the food system on a broader scale can serve as ‘positive disruptors,’ to drive the type of transformations across food systems and land uses needed to meet Paris Agreement Climate Change targets,” says David Styles, study coordinator and honorary lecturer at Bangor University (Bangor University, 2023)
Furthermore, the study by Costa and co-authors highlights the huge role that land use policy can play in leveraging climate benefits from ethical consumption choices. Livestock production is directly or indirectly responsible for most of the land used for food production globally. Effective policies that promote nature-based solutions for climate change, such as afforestation on land spared from livestock production, could multiply the climate benefits of dietary shifts by up to three-fold. (Bangor University, 2023)
References
Costa MP, Saget S, Zimmerman B, et al. Environmental and land use consequences of replacing milk and beef with plant-based alternatives. Journal of Cleaner Production. 2023;424, 138826. https://doi.org/10.1016/j.jclepro.2023.138826
Bangor University. Unlocking the climate benefits of dietary substitutions: The impact of land use policy. Phys.org. October 16, 2023. Available at:
https://phys-org.cdn.ampproject.org/c/s/phys.org/news/2023-10-climate-benefits-dietary-substitutions-impact.amp
EAT Forum. The EAT-Lancet Commission on Food, Planet, Health. 2019. Available at:
https://eatforum.org/eat-lancet-commission/#:~:text=It%20emphasizes%20a%20plant%2Dforward,%2C%20vegetables%2C%20nuts%20and%20legumes.
Zhang S, Dukuzimana J, Stubbendorff A, et al. Adherence to the EAT-Lancet diet and risk of coronary events in the Malmö Diet and Cancer cohort study. American Journal of Clinical Nutrition. 2023;117(5):903-909. doi: 10.1016/j.ajcnut.2023.02.018.
Karavasiloglou N, Thompson S, Pestoni G, et al. Adherence to the EAT-Lancet reference diet is associated with a reduced risk of incident cancer and all-cause mortality in UK adults. One Earth. 2023; https://doi.org/10.1016/j.oneear.2023.11.002
Ojo O, Jiang Y, Ojo OO, Wang X. The association of planetary health diet with the risk of type 2 diabetes and related complications: A systematic review. Healthcare (Basel). 2023;11(8) :1120. doi: 10.3390/healthcare11081120
Footnotes:
*Eutrophication is a process which occurs when the environment becomes enriched with nutrients, increasing the amount of plant and algae growth to estuaries and coastal waters. Excessive nutrients lead to algal blooms and low-oxygen (hypoxic) waters that can kill fish and seagrass and reduce essential fish habitats. Many of these estuaries also support bivalve mollusk populations (e.g., oysters, clams, scallops), which naturally reduce nutrients through their filter-feeding activities (NOAA, 2023).
Eutrophication sets off a chain reaction in the ecosystem, starting with an overabundance of algae and plants. The excess algae and plant matter eventually decompose, producing large amounts of carbon dioxide. This lowers the pH of seawater, a process known as ocean acidification.
**Acidification slows the growth of fish and shellfish and can prevent shell formation in bivalve mollusks. This leads to a reduced catch for commercial and recreational fisheries, meaning smaller harvests and more expensive seafood. (NOAA, 2023)
For more information, see: NOAA, National Ocean Service. What is eutrophication? (2023)
Sustainable RDN 