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

Can You Be Addicted to Sugar?

Can You Be Addicted to Sugar?

This article was written by Associate Registered Nutritionist (ANut) Sophie Gastman, and reviewed by Registered Dietitian Maeve Hanan. Put simply, sugar …
Issues With BMI

Issues With BMI

This article was written by Associate Registered Nutritionist (ANut) and Content Creator at Dietetically Speaking Sophie Gastman (reviewed by Registered …
Get To Know Our Dietitians!

Get To Know Our Dietitians!

For Dietitian's Week 2022 we have interviewed our current Dietitians in the Dietetically Speaking Clinic about what led them to …
Recent Studies on the Impact of COVID-19 on Eating Disorders

Recent Studies on the Impact of COVID-19 on Eating Disorders

This article was written by Registered Nutritionist Sophie Gastman (reviewed by Registered Dietitian Maeve Hanan). More evidence is emerging about how …
Intermittent Fasting and Disordered Eating

Intermittent Fasting and Disordered Eating

Intermittent fasting has been one of the most popular (and most googled) diets for the past few years. Although there is …
The Link Between Disordered Eating and IBS

The Link Between Disordered Eating and IBS

This article was written by Registered Associate Nutritionist Sophie Gastman and Registered Dietitian Maeve Hanan. There are a number of links …
Why Do We Need Fats in Our Diet?

Why Do We Need Fats in Our Diet?

We recently explored the importance of body fat. This article by Registered Nutritionist Sophie Gastman (reviewed by Registered Dietitian …
The Functions of Body Fat

The Functions of Body Fat

This article was written by Registered Nutritionist and Dietetically Speaking intern Sophie Gastman and reviewed by Registered Dietitian Maeve Hanan. Although body fat has a …
Is Obesity a Disease?

Is Obesity a Disease?

Please note: I don't usually use the terms 'obese' or 'overweight' as these categories are flawed and often stigmatising. But …
Intuitive Eating Linked With Reduced Disordered Eating

Intuitive Eating Linked With Reduced Disordered Eating

This article was written by Nutritionist and Dietetically Speaking Intern Hanna Tejani and reviewed by Registered Dietitian Maeve Hanan. The EAT Study (2010-2018) …
What is Weight-Inclusive Care?

What is Weight-Inclusive Care?

This article by Maeve Hanan (Registered Dietitian & Founder of Dietetically Speaking) will explain what weight-inclusive care means and why …
Issues With Weight-Centric Health Care

Issues With Weight-Centric Health Care

This article was written by Maeve Hanan (Registered Dietitian & Founder of Dietetically Speaking. Traditional health care models tend to be …