What is a sustainable diet?
“Sustainability”. So far, so buzzword. And when it comes to ‘sustainable diets’ even more confusing. But with everyone from Michael Gove, to that Instagram influencer you follow who’s suddenly gone vegan talking about more sustainable diets, what does it actually mean?
First off, is it actually a thing, or just a fad?
Reorienting food systems so that they provide enough nutritious food for everyone, without also seriously screwing the environment over is one, if not the, most pressing question for public health nutrition in the 21st century.
While increasingly obesogenic environments have led to a growing burden of noncommunicable diseases (such as type 2 diabetes), climate change is simultaneously posing new threats to the global food system by threatening sufficient production of healthful foods. With rates of nutrition-related chronic diseases on the up (partly due to poor quality diets), rising global temperatures and greenhouse gas emissions (GHGEs) are impacting upon agricultural systems, decreasing vegetable yields, affecting soil quality, and directly impacting food production. With food consumption and production responsible for a significant proportion of manmade GHGEs - around 24% of total emissions – could changing how we eat help the planet?
Given the current situation, it’s perhaps no surprise that the links between planetary and human health are increasingly on the agenda, with the FAO (the UN’s Food and Agricultural Organisation) recently endorsing dietary patterns that are both healthy and respectful of the environment, despite only 4 countries currently mentioning sustainability in their national dietary guidelines. Can we all get a round of applause for Brazil, Sweden, Germany and Qatar please?
With much made of the fact that animal produce contributes significantly to agricultural emissions (livestock accounts for 14.5% of total global anthropogenic GHGEs), public awareness of the links between planetary and human health has tended to focus mostly on the environmental impact of meat and dairy. A recent UK consumer survey found a six-fold increase in numbers following a vegan diet between 2016 and 2018, with people citing both environmental and health concerns as their motivation for changing their diets. Yet as ever (!), the emphasis to date has been on getting individuals to switch things up, rather than a wider focus on changing the food system as a whole. While we all have a part to play in living more sustainably, sustainable diets are more complex than often portrayed.
Defining sustainable diets
Diagram from Johnston JL, et al. Understanding Sustainable Diets: A Descriptive Analysis of the Determinants and Processes That Influence Diets and Their Impact on Health, Food Security, and Environmental Sustainability. Adv Nutr. 2014
The rather attractive flower diagram to the right does a better job defining a sustainable diet than I can, but the key thing to note is that a sustainable diet is about much more than going vegan (although if that works for you, smashing, just be sure to take a B12 supplement!).
The scope of what eating sustainably encompasses is large, and includes animal welfare practices, food waste, better working conditions for food workers, and agricultural practices. In fact, the FAO’s widely used definition of a sustainable diet is a pretty all-encompassing one, including all facets of sustainability:
“Sustainable Diets are those diets 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 optimizing natural and human resources.”
What is clear however, is that eating more sustainably (whatever that looks like for you) can be good for both our health and the wider environment. There’s often quite a bit of overlap between sustainable (read; food that’s both ecologically and ethically friendly) and more healthful foods. Research has highlighted the similarities between eating for better long-term health and eating more sustainably, with modelling studies showing the dual benefits of this approach.
A large modelling study in 2015 calculated that if UK diets met the World Health Organisation’s recommendations for a healthy diet, GHGEs would decrease by 17%, with the added bonus of increasing life expectancy by over 8 months. A systematic review of 63 studies the following year supported this study by finding more sustainable diets could confer both health and environmental benefits. Yet herein lies the catch, what types of food should be included or excluded in a sustainable diet? What is this more healthful way of eating that’s handily also environmentally friendly? Well, the review found some 14 sustainable dietary patterns, including vegetarian, vegan, pescatarian, replacing ruminant (meat from methane producing animals like cows) with monogastric meat (i.e. chicken), balanced energy intake, following healthy guidelines, Mediterranean diet, New Nordic diet, and meat reduction.
Broadly speaking, basing your meals around whole foods and plant foods is more sustainable than a heavily animal and processed/packaged food focussed diet. My favourite diagram that nicely illustrates this overlap is the Barilla Centre’s ‘Double Food Pyramid’ below:
Diagram from Ruini LF, et al. Working toward Healthy and Sustainable Diets: The “Double Pyramid Model” Developed by the Barilla Center for Food and Nutrition to Raise Awareness about the Environmental and Nutritional Impact of Foods. Front Nutr. 2015
How to navigate it all
It’s important that the focus on sustainable diets doesn’t become a new version of ‘clean eating’; imbued with moral meaning, exclusionary diet habits, and an accompanying price premium that puts sustainable eating out of reach for many.
Rather like climate change, global cooperation across a number of different sectors is required for a true paradigm shift. Think action from governments, policy-makers, farmers, manufacturers, private corporations, retailers AND individuals.
A bit of a cliché, but when it comes down to it, the little things do add up. Vegan diets are not the only thing we can do to make a difference - what to eat in order to be sustainable is an incredibly complex topic and fraught with complexity. Eating locally bought tomatoes for example, might help to reduce food mileage, but the cost of heating the greenhouses needed to grow tomatoes in the UK might mean a higher overall carbon footprint compared to those shipped in from sunnier climes. The systematic review discussed earlier in this article found that the largest environmental benefits overall were seen in those diets which most reduced amounts of animal-based foods, yet conversely, the review also found that the vegan diet scored worst when it came to water usage.
And of course, there are many different ways to live sustainably that don’t just revolve around what we eat. As ever, we shouldn’t look only to our diets for all the solutions, or to make a statement about who we are in the world. The paradox at the heart of ‘green consumerism’ is that consuming much of anything isn’t actually very green. A study reviewing some 39 papers and published just last year, reported that the top four most effective ways to reduce individual carbon footprints are to have one fewer child, live car free, avoid Trans-Atlantic flights, and buy green energy (eating a plant-based diet came in at number 7).
But when it comes to a few fairly fool-proof ways to live more sustainably when it comes to the food we buy and eat, how about:
- Using eco-labels to guide your choices when shopping. Fairtrade, Organic, RSPCA assured, and Marine Stewardship Council (MSC) labels all indicate that a product has met pre-defined criteria for various sustainable standards of production
- Eating one or two more plant-based meals a week (check out the pulse and plant recipe sections on the website here), and by plant-based I mean focussed around grains, veg, and pulses.
- Watching how regularly you eat plant-based alternatives with a large water footprint, like avocados and almond milk.
- Reducing how much food you waste. According to WRAP , 60% of food waste is avoidable, with an estimated 10 million tonnes of food wasted every single year; an environmental cost of 20 million tonnes of greenhouse gas emissions. (Check out this blog for tips on how to reduce your food waste.)
- Buying veg and fruit when it’s in season. Not only will it likely be tasty, but it may well be cheaper too.
- Shoving a ‘bag for life’ or cotton carrier bag in your handbag for the next time you pop into the supermarket on your way home to pick a couple of things up
Other general references
McMichael AJ, Powles JW, Butler CD, Uauy R. Food, livestock production, energy, climate change, and health. Lancet. 2007;370(9594):1253–63. Available from: http://www.sciencedirect.com.ez.lshtm.ac.uk/science/article/pii/S0140673607612562? via%3Dihub
World Health Organisation, Food and Agriculture Organisation of the United Nations. WHO Technical Report Series, report of a joint WHO/FAO expert consultation: Diet, nutrition and the prevention of chronic diseases. WHO. 2003
Fischer CG, Garnett T. Plates, pyramids, planet: Developments in national healthy and sustainable dietary guidelines: a state of play assessment. FAO, FCRN. 2016.