An investigation into the environmental impact of plant-based dairy alternatives compared with dairy milk in the UK

Plant based milk alternatives (PBMA) have increased in popularity whilst the purchase of dairy milk has declined. In addition to allergies/intolerances to dairy milk, perceived health benefit and moralistic concerns, there is growing concern over the environmental impact of food/drink (1). The British Dietetic Association’s ‘One Blue Dot’ campaign has published guidance on sustainable eating, including reducing dairy (2). Studies have found that PBMA have a lower environmental impact than animal-based milks. However, some comparisons have been limited in scope and/or not compared like with like. We previously investigated differences in cost, nutrient profile and product composition between all types of PBMA and dairy milk. Investigating differences in environmental impact complements this and will enable healthcare professionals to draw on a strong evidence base when discussing milk choice in line with patients’ nutritional needs and preferences.
A search was completed for all milks from the top 10 UK supermarkets. Data from ‘Estimating the environmental impacts of 57,000 food products’ was accessed (3). For available milks, ‘Fifty’, ‘Lower twenty fifth’ and ‘Upper seventy fifth’ values per 100g for greenhouse gas emissions (Kg Co2e), scarcity weighted water use (L), land use (m2), aquatic eutrophication potential (g PO4eq), acidification (PH), and water use (L) was collected. Median (and IQR) PBMA, dairy milk and sub type of milk were calculated. A ‘total environmental score’ per 100g (ranging from 0 (no impact) -100 (highest impact)) was collected for available milks. Median (and IQR) PBMA, dairy milk and sub type of milk were calculated. Mann Whitney U and Kruskal Wallis (for non-normality in groups) determined differences between PBMA and dairy milk and milk sub types.
From 190 products (123 dairy, 67 PBMA), dairy milk had a 75% higher median ‘total environmental score’ than PBMA (p<0.0001). However, almond, cashew, combination, hazelnut and walnut milk had scores higher than dairy. Dairy milk had a higher land use, greenhouse gas emissions, eutrophication, water scarcity and acidification than PBMA. However, almond, cashew, combination, hazelnut and walnut milks had higher for water scarcity than dairy, and almond and rice milk had higher water use than dairy.
Findings concurred with previous research (3,4). Although there were significant differences in ‘total environmental score’ between dairy (1.5/100) and PBMA (0.4/100), these differences are negligible when compared with the total environmental score of meat (e.g. beef 32/100 (3)). Limitations of the study include using secondary data that was collated from multiple sources and does not cover all impacts associated with agriculture e.g. postproduction, processing, packaging, and transportation (3) or different systems of production at the farm level.
Overall, this study has shown that overall dairy milk had a higher environmental impact than PBMA, however there are exceptions, and this should be considered when choosing PBMA.
References

Heard H & Bogdan A (2021) Healthy and sustainable diets: Consumer poll Food Standards Agency
2. BDA (2020) One Blue Dot: Eating patterns for health and environmental sustainability
3. Clark M et al (2022) PNAS 119(33) [Available at https://www.pnas.org/doi/full/10.1073/pnas.2120584119]
4. Poore J & Nemecek T (2018) _Science_360(6392), 987–92