How Environmentally Friendly are Plant-Based Diets?

Published on

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.


Sustainable Eating

The food supply-chain can impact the environment in different ways, such as:

  • Greenhouse gas emissions (e.g. carbon dioxide, methane and nitrous oxide) from production, transport and storage of food
  • Land and water use
  • Soil, air, and water quality
  • Impacting on the diversity ecosystems

 

But the Food and Agricultural Organisation (FAO) definition if a sustainable diet is wider than just the environment, this is defined as a diet: “with low environmental impacts which contribute to food and nutrition security and to healthy life for present and future generations. Sustainable diets are protective and respectful of biodiversity and ecosystems, culturally acceptable, accessible, economically fair and affordable; nutritionally adequate, safe and healthy; while optimising natural and human resources‟1.

Carbon Footprint

The production of meat and dairy products are the largest contributors to Green House Gas (GHG) emissions related to diet2-5.

Beef cattle and dairy cattle release the most emissions overall2-5. But in some countries dairy farming has made good progress in reducing GHG emissions (by 30.7% over the 25 – 30 years), due to increasing milk production per cow6.

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

 

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.

Furthermore, 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 women4.

This study also calculated that avoiding red & 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 potatoes8.

Overall, it is thought that switching to a plant-based diet on a global scale would reduce greenhouse gas emissions by 49%9

Other Environmental Factors

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 protein7.

It also takes less resources to produce most types of plant-based milks as compared with cow’s milk, but this isn’t true for all plant-based milks9. For example, it makes about 17 times more water to produce almond milk compared to cow’s milk per litre (although cow’s milk emits almost 10 times as much GHGs)9

Other factors related to producing plant-based foods include: use of agrochemicals (and the subsequent effect on biodiversity) and the energy used by  heat lamps3,10.

Overall, it has been estimated that a global- shift towards plant-based diets would reduce land use by 76%.9

It has also been estimated that this would reduce the impact on water and by reducing acidification by 50%, and reducing eutrophication by 49%.9 

Another study from 2016 found that if the UK population’s intake matched the Eatwell Guide, this would lower the overall environmental impact related to diet by 33%.11

Graph reference: https://www.carbontrust.com/media/672635/phe-sustainable-diets.pdf

Fish consumption can 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 overexploited12. For more information about this, check out this post about eating fish sustainably

Nutritional Content

A sustainable diet also needs to be nutritionally adequate1.

The nutritional benefits of animal-based products include:

  • Good sources of protein and B-vitamins (including vitamin B12)
  • Oily fish is a great source of omega-3 fat
  • Red meat is a really source of bio-available iron & zinc 
  • Dairy and fish are good sources of iodine
  • A 200ml glass of milk provides: 31% of the daily recommended intake of calcium and 28% of phosphorus13  

However, a varied plant-based diet which contains a moderate amount of dairy, or calcium-fortified dairy alternatives, should provide a balanced intake of nutrients. Balanced plant-based diets are also associated with numerous health benefits. For information about how to achieve a well-balanced plant-based diet, check out my post: Nutritional Advice for Vegans & Vegetarians.

Soya milk contains a higher level of protein than other plant-based milks. A low intake of protein isn’t a concern for most people, as most already consume more protein than the recommended protein intake.  But may be an issue for those at a higher risk of malnutrition, such as older people or infants.

Image reference: PEN (2017) “Plant-based Beverages – Are They Really Healthier For Young Children?”

 

For more information on how to achieve a nutritionally-balanced plant based diet check out my previous posts: Nutritional Advice for Vegans and Vegetarians, and What You Need to Know About Vegetarian Meat Alternatives.

Overall:

The concept of a ‘sustainable diet’ is complex and there isn’t currently one solid set of guidelines to follow. 

Sustainable choices on an individual and group level can nudge companies to use more  environmentally-friendly methods. However, it it is worth bearing in mind that changes may need to occur higher up (e.g. at legislation and production level) to make a significant difference in terms of the environment.

But moving towards a more plant-based diet is likely to benefit the environment as well as public health.

A plant-based diet, doesn’t need to be a plant-ONLY, as sustainable eating messages don’t need to be black and white. 

A practical and realistic message to spread is for most people to eat more plants and a little less meat and dairy (i.e. follow the Eatwell Guide), rather than promoting veganism as the only environmentally-friendly option.

References:

  1. FAO (2010) “Final document: International Scientific Symposium Biodiversity and Sustainable Diets: United against Hunger. 3-5 November 2010” 
  2. Gerber et al. (2013) “Tackling climate change through livestock – A global assessment of emissions and mitigation. Food and Agriculture Organization of the United Nations”
  3. BDA Policy Statement on Sustainable Diets (2017)
  4. 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
  5. Perignon et al. (2016) “Improving diet sustainability through evolution of food choices: review of epidemiological studies on the environmental impact of diets”
  6. DAERA-NI (2017) “Greenhouse gas emissions Northern Ireland Dairy Farm Sector”  
  7. Pimental & Pimental (2003) “Sustainability of meat-based and plant-based diets and the environment”

  8. Wallen et al. (2004) “Does the Swedish consumer’s choice of food influence greenhouse gas emissions?” 
  9. Poore & Nemecek (2018) “Reducing food’s environmental impacts through producers and consumers” 
  10. Riley & Buttriss (2011) “A UK public health perspective: what is a healthy sustainable diet?” 
  11. The Carbon Trust (2016) “The Eatwell Guide: a More Sustainable Diet”
  12. FAO Fisheries and Aquaculture Department (2012) “The State of World Fisheries and Aquaculture 2012. Rome: Food and Agriculture Organization of the UN”
  13. The Dairy Council (2016) “Milk Factsheet”

Testimonials

Maeve has been consulting on The Food Medic Educational Hub for 12 months now and has been a huge asset to the team. Her ability to translate some very nuanced topics in nutrition into easy-to-follow, informative articles and infographics is really admirable.

Dr Hazel Wallace

Founder of The Food Medic

Maeve is incredibly talented at sharing scientific information in an easy to understand way. The content she shares with us is always really interesting, clear, and of very high quality. She’s one of our favourite writers to work with!

Aisling Moran

Senior UX Writer at Thriva Health

Maeve has written extensively for NHD magazine over the last few years, producing a wealth of dietetic and nutritional articles. Always evidence based and factual, Maeve creates material that is relevant and very readable. She provides high quality work with a professional and friendly approach. Maeve is a beacon of high quality knowledge and work within the nutrition writing community; and someone NHD magazine is proud to work with.

Emma Coates

Editor of Network Health Digest


Support Dietetically Speaking

More from Dietetically Speaking

Are Vegan Diets Low in Certain Minerals?

Are Vegan Diets Low in Certain Minerals?

My wonderful intern Zachary Wenger has previously written about whether protein or certain vitamins are nutrients of concern for vegans. …
Gluten 101

Gluten 101

Thank you to Student Dietitian Marcos Gregoriou for writing this blog post about gluten, the gluten-free diet and the risks …
Simple Shakshuka Recipe

Simple Shakshuka Recipe

This is such a handy and delicious brunch option which only takes about 20 minutes to make. I used frozen veg …
IBS & The Low FODMAP Diet

IBS & The Low FODMAP Diet

This article was first published in October 2019 Thriva Newspaper. Irritable bowel syndrome (IBS) is a disorder which occurs when a …
The Lectin-Free Diet

The Lectin-Free Diet

This article was first published in the November 2019 edition of NHD magazine. What is the Lectin-free Diet?  This diet involves heavily …
Vitamins for Vegans

Vitamins for Vegans

This article was written by Zachary Wenger, who is a dietetic student and a vegan. As a follow-up to our previous …
Daal Recipe

Daal Recipe

This recipe was created by my partner Anthony O'Neill — it is DAAL-icious so I hope you enjoy it as …
Is Protein Intake an Issue for Vegans?

Is Protein Intake an Issue for Vegans?

This article was written by Dietetically Speaking’s intern Zachary Wenger. Zack is a Student Dietitian and a Vegan himself. Protein might …
Can Type 1 Diabetes Management Contribute to an Eating Disorder?

Can Type 1 Diabetes Management Contribute to an Eating Disorder?

This guest post was written by Eloize Kazmiersky. Eloize graduated has a BSc Nutrition degree from the University of Nottingham …
Your No-Nonsense Guide to Eating Well

Your No-Nonsense Guide to Eating Well

I am SO excited to tell you about this book which I have just released!I was inspired to write Your No-Nonsense …
The Pros and Cons of Low-Carb Diets

The Pros and Cons of Low-Carb Diets

This guest post was written by Dr Harriet Holme (MA Hons Cantab, MBBS MRCPCH, PhD, RNutr). Harriet studied medicine at …
Does Green Tea Live Up To The Hype?

Does Green Tea Live Up To The Hype?

This article was written for NHD magazine, and was published in the February 2020 edition. Green tea is often touted as …