When a new study prompts media headlines like "Being vegan isn’t as environmentally friendly as you think", it's time for a closer look at the science.
By Dr Jeanette Di Leo
A recent modelling study, published in a low-tier journal, reported that more people could be fed on a partly omnivorous diet (where up to 40% of meals included meat) or on a vegetarian diet than on a vegan one (Peters et al., 2016). Anti-vegan headlines were quick to pop up, from We Can Feed More People on an Omnivore Diet than a Vegan One, Study Shows to Being vegan isn’t as environmentally friendly as you think.
Never mind that the study only focussed on U.S. agricultural land, not global conditions. Or that, even by the authors’ calculations, a vegan diet could feed around 735 million people, compared to 402 million on the Standard American Diet; or that there is a plethora of health problems linked to the consumption of animal products. No, ‘vegans are wrong’ was the take-home message. Bacon-lovers can sleep soundly tonight.
So why did the authors estimate that a vegetarian diet could feed 72 million more people than a vegan diet, when study after study shows that land use required for animal products is higher than for plants (e.g., Nijdam et al., 2012)?
They based their calculations on three categories of land: cropland in cultivated crops (field crops, fruits, vegetables, nuts), grazing land, and cropland in perennial forage crops. The latter “included hay crops and grazing on land which could be cropped but is used for pasture”.
It was only the meat-eaters who required grazing land. Vegans required zero perennial cropland in that scenario (under the assumption that that land would only grow hay or similar feed, not, say, perennial legume crops for human consumption). And that is where the difference in food yield appears to stem from: feeding cows and chickens from perennial forage crops. Vegans had the highest amount of unused cropland.
Now I ask you: is that such a bad thing?
Globally, 75% of all agricultural land (including pasture and cropland) are currently used for animal production (Foley et al., 2011; Kastner et al., 2012). Livestock production is the major driver of land use change (Alexander et al., 2015), and land use change is bad news for soil degradation as well as climate change. Furthermore, 30% of global biodiversity loss are linked to livestock production and its contribution to overgrazing, degradation of grasslands, and land conversion (Westhoek et al., 2011).
So if a vegan diet means that the U.S. can, without trade, feed its current populace 2.4-fold instead of 2.6-fold on a vegetarian diet or 2.5-fold on an occasional meat-including diet (Peters et al., 2016), then I say, that’s a small price to pay.
Having said all that, it’s a bit telling that Peters et al. at no point mention a related, much more sophisticated study published recently in high-impact journal Nature Communications by Erb et al.. They wanted to find out how we could feed the global population of over 9 billion people by mid-century with zero deforestation. They tested 500 different scenarios, taking into consideration things like crop yields, grazing intensity, cropland demand, and global trade. Only if the world adopted a vegan diet could 100% of their scenarios be fulfilled; 94% on a vegetarian diet, and merely 15% on the meat-heavy diet that the world is veering towards.
In other words: we could feed the entire global population on a vegan diet, without cutting down another tree and even, as the authors point out, at the lowest yield levels. On diets that include meat, eggs, and dairy? A lot less likely.
Lastly, it might be worth pointing out that the Peters et al. study was partly funded by the W.K. Kellogg Foundation, which is known for heavily funding dairy. This need not mean anything, but it does leave a strange taste in my mouth.
To find out more about the detrimental effects animal products have on our health, and the abundance of health benefits of a vegan diet, check out Viva!Health’s new, fully-referenced Incredible Vegan Health Report.
Alexander, Peter, et al. "Drivers for global agricultural land use change: The nexus of diet, population, yield and bioenergy." Global Environmental Change 35 (2015): 138-147.
Erb, Karl-Heinz, et al. "Exploring the biophysical option space for feeding the world without deforestation." Nature Communications 7 (2016).
Foley, Jonathan A., et al. "Solutions for a cultivated planet." Nature 478.7369 (2011): 337-342.
Kastner, Thomas, et al. "Global changes in diets and the consequences for land requirements for food." Proceedings of the National Academy of Sciences 109.18 (2012): 6868-6872.
Nijdam, Durk, Trudy Rood, and Henk Westhoek. "The price of protein: Review of land use and carbon footprints from life cycle assessments of animal food products and their substitutes." Food Policy 37.6 (2012): 760-770.
Peters, Christian J., et al. "Carrying capacity of US agricultural land: Ten diet scenarios." Elementa: Science of the Anthropocene 4.1 (2016): 000116.
Westhoek, H. J., et al. "The protein puzzle: the consumption and production of meat, dairy and fish in the European Union." European Journal of Food Research & Review 1.3 (2011): 123-144.