How Environmentally Friendly are Plant-Based Diets?

Many people choose to follow a plant-based diet for environmental reasons, so I wanted to dig into the research about how much of an impact this has.

The production of meat and dairy products is the largest contributor to Green House Gas (GHG) emissions related to diet^1-4.

Beef cattle and dairy cattle release the most emissions overall^1-4. But in some countries dairy farming has made good progress in reducing GHG emissions, due to increasing milk production per cow⁵.

Graph reference: http://www.fao.org/3/a-i3437e.pdf   

A study based on the UK National Diet and Nutrition Survey (NDNS) found that meat intake accounted for 31% of dietary CO2 emissions for men and 27% of  dietary CO2 emissions for women³.

This study also calculated that avoiding red and processed meat at a population level would reduce CO2 emissions by 27.8 million tonnes per year.

Similarly, beef and fish have been found to produce 38 times the amount of GHG emissions as compared with potatoes⁶.

Water use also needs to be considered. It takes roughly 100 times more water to produce 1 kg of animal protein as compared to 1 kg of grain protein^7.

Similarly, energy input from fossil fuels used to produce 1 kcal of animal protein is more than 11 times higher than production of the same amount of grain protein⁷.

Fish consumption can also damage the environment by disrupting ecosystems. Overfishing is a big issue, in 2012 it was announced that 87% of all fish stocks were either fully exploited or overexploited⁸. For more information about this, check out this post about eating fish sustainably. 

A review by Riley & Buttress (2011) highlighted that the concept of a ‘sustainable diet’ is complex, and there is unlikely to be one solid set of guidelines⁹. However, this review also acknowledged that a moderate reduction in meat and dairy consumption in the UK is likely to reduce GHG emissions as well as improving health.

Plant-based foods also have an environmental impact.

Therefore issues such as land use, water use, biodiversity, use of agrochemicals, use of energy in heat lamps and the nutrient needs of the population also need to be considered as well^2,9.

In 2016 the updated version of the UK Eatwell Guide was released which included an emphasis on sustainable eating and plant-based options. An analysis by The Carbon Trust found that the updated Eatwell Guide had a 32% lower environmental footprint as compared to the results of the National Diet and Nutrition Survey from 2008 – 2012¹⁰.

Overall plant-based diets seem to have the environmental advantage, but a moderate reduction in meat and dairy consumption by following the updated Eatwell Guide also appears to be beneficial for the environment.

1. Gerber et al. (2013) “Tackling climate change through livestock – A global assessment of emissions and mitigation. Food and Agriculture Organization of the United Nations”
2. BDA Policy Statement on Sustainable Diets (2017)
3. Aston et al. (2012) “Impact of a reduced red and processed meat dietary pattern on disease risks and greenhouse gas emissions in the UK: a modelling study“
4. Perignon et al. (2016) “Improving diet sustainability through evolution of food choices: review of epidemiological studies on the environmental impact of diets”
5. DAERA-NI (2017) “Greenhouse gas emissions Northern Ireland Dairy Farm Sector”  
6. Wallen et al. (2004) “Does the Swedish consumer’s choice of food influence greenhouse gas emissions?” 

7. Pimental & Pimental (2003) “Sustainability of meat-based and plant-based diets and the environment”

8. FAO Fisheries and Aquaculture Department (2012) “The State of World Fisheries and Aquaculture 2012. Rome: Food and Agriculture Organization of the UN”
9. Riley & Buttriss (2011) “A UK public health perspective: what is a healthy sustainable diet?” 
10. The Carbon Trust. The Eatwell Guide: a More Sustainable Diet. 2016 https://www.carbontrust.com/media/672635/phe-sustainable-diets.pdf).