WHAT’S THE BEST DIET FOR OUR PLANET?
The neverending deluge of information about our food choices can be baffling. So should we all become vegan, or can we really have our steak and eat it?
Diet can be a contentious issue, subject to the forces of personal ethics, religious beliefs and health concerns. But when it comes to the environment, for many people it’s an open-and-shut case. “The evidence is all there, you just need to look for it,” my vegan friend told me recently, with the kind of sanctimonious air that puts some people off veganism altogether.
The thing is, although I’m not a vegan myself, I suspect he’s probably right. While I’m quite sure this is not the stated aim of most vegans, abstaining from animal products does seem to give you the moral high ground in the environmental stakes. I’ve watched Cowspiracy, I know the deal. At the same time, I’ll admit to being a little put off by how self-assured some people seem in their dietary choices. Seldom does all the evidence point in one direction, and when considering something as multifaceted as the global food system, perhaps it’s unwise to generalise.
In recent years, scientists and the public have become increasingly aware that the food we eat can have negative impacts on the planet. With this in mind, it’s worth asking – whichever side of the fence you’re on – whether the evidence really is ‘all there’, and whether there exists a diet that is objectively best for the environment.
This is not a straightforward issue. According to figures from the Consultative Group on International Agricultural Research (CGIAR), one-third of our greenhouse gas emissions come from agriculture. But that’s just one factor. Our food system is also the leading cause of deforestation, land use change and biodiversity loss in the world. Then there’s overfishing, pollution, groundwater depletion, excessive fertiliser use and pesticides to contend with as well. With all these issues to consider, a ‘sustainable’ diet might mean different things depending on who you talk to. However, certain trends cut through the noise – most notably, an emphasis on more plant-based diets.
The idea that vegetarianism is good for the planet is relatively new. Back in 1971, a visionary
book by Frances Moore Lappé entitled Diet For A
Small Planet suggested that world hunger could be remediated if less emphasis was placed on meat in Western diets. Her recipes for spinach lasagne and soy burgers caused a stir at the time, but skip forward 46 years and official guidelines everywhere from the Netherlands to the US emphasise lower meat consumption for a healthy body and a healthy planet. Vegetarianism has gone mainstream. In a report from the US-based 2015 Dietary Guidelines Advisory Committee, the authors concluded: “Consistent evidence indicates that, in general, a dietary pattern that is higher in plant-based foods … and lower in animal-based foods is more health promoting and is associated with lesser environmental impact than is the current average US diet.”
These are not empty words. Study after study has demonstrated the beneficial effects of a plant-based diet for the environment. A paper published last year in
Proceedings Of The National Academy Of Sciences
concluded that a mass switch to vegetarianism would bring down food-related greenhouse gas emissions by a whopping 63 per cent, while even just sticking to global health guidelines regarding meat consumption (so laying off the burgers a bit) would be enough to reduce emissions by 29 per cent.
As for veganism, it does seem to be edging ahead in the planet-saving stakes. Many of the issues that arise from farming livestock for meat – methane emissions from animal digestion, pollution from farms, energy-intensive feeds – also apply to the dairy and egg industries. If widespread veganism was enacted, that 63 per cent reduction in emissions shoots up to 70 per cent.
IN DEFENCE OF CARNIVORES
These seem like hard figures to ignore, and yet ignored they are by the vast majority of people. While plant-based diets have now been normalised in a way that was probably unimaginable in Lappé’s day, practising vegetarians and vegans are still relatively thin on the ground. It’s thought only 2 per cent of the UK population is vegetarian, and less than 1 per cent is vegan.
But stop the press! Maybe cutting out animal products entirely, or even nearly entirely, isn’t necessarily the way to go. There have been studies published in reputable journals which suggest that vegetables may not be our sole salvation. Back in 2015, a particular paper caused a media firestorm when its lead author, Prof Paul Fischbeck of Carnegie Mellon University, made the declaration that “eating lettuce is over three times worse in greenhouse gas emissions than eating bacon”. “LETTUCE WORSE THAN BACON” screamed the headlines, as commentators smugly observed that
“While plantbased diets have now been
normalised, vegetarians and vegans are still relatively thin on the ground”
vegetarianism isn’t all it’s cracked up to be.
Other research has suggested that at least some degree of carnivory could be beneficial. A recent analysis of 10 distinct diets, each with a different ratio of meat and animal products, saw veganism relegated to fifth position when it came to maximising sustainable land use, below different degrees of vegetarianism and omnivory. This comes as a blow to vegans who tend to assume, understandably, that due to the well-documented problems with livestock farming, their diet plan automatically places them in the top spot.
THE DEVIL IN THE DETAIL
How can researchers come to such different
conclusions? Well, the short answer is because they’re trying to answer a complicated question. To work out the best diet for the planet, scientists tally up the environmental costs of the production, transportation and marketing of foods, and then compare the options. Yet there are many such costs involved, and therefore many potential metrics. Some researchers completely ignore certain aspects, such as the amount of food that is wasted, while others place more emphasis on aspects that they deem to be most relevant.
For example, there is no question that red meat produces far more emissions than vegetable protein sources like lentils and beans – around 13 times more, in fact. But if you’re focusing on land use, then cows and sheep start to make a lot of sense. Livestock, and food for livestock, can be farmed on land that’s unsuitable for human crops, so if that land can be put to good use it will improve the efficiency of food production in a given area.
As for the idea that lettuce is worse for the environment than bacon, the researchers had opted to analyse emissions on a per calorie basis. This seems an unfair comparison. After all, no one is suggesting that vegetarians replace two rashers of bacon at breakfast with the 3.3kg of lettuce it would take to match them, calorie-wise. But what Fischbeck and his colleagues wanted to emphasise was the need to consider foods on their individual merit, rather than assuming that just because you have chosen diet A or diet B, you are automatically saving the world.
VARIETY IS THE SPICE OF LIFE
This is a good point. There is an awful lot of variety in green credentials, even within food groups. Beef
and lamb produce far more emissions than pork, which in turn produces more than chicken. As for fish, the variation in impact is enormous, so diverse are the means by which different species are caught or farmed and the levels of threat they are all under in different parts of the world.
Fruits and vegetables are even more complicated. Robust produce that can be grown in fields, such as cabbage and potatoes, result in relatively low greenhouse gas production, but if a plant requires intense refrigeration, or has to be grown in a hot house, alarm bells begin to ring. Similarly, vegetables which must be flown great distances before they arrive on your plate come with a sizeable emissions price tag. That’s before you even consider the huge quantities of water needed to grow citrus fruits, or the pesticides that are pumped into banana plantations. Greenhouse gases, though the most widely used measure of impact, only tell one side of a far more complicated story, and those who opt for more plant-based diets must be wary of replacing the animal parts of their diet with plants that cause harm in other ways.
The fact is, whichever label you choose to define yourself – vegan, vegetarian, pescetarian or omnivore – there’s no room for complacency. Ultimately, the choices you make about your food are just as important as the diet tribe you belong to.
Another layer of complexity is the variety of farming strategies in use. Rather than demonising meat, some argue, policies could ensure that livestock farming is more efficient and produces fewer greenhouse gases. This may sound a little too good to be true, but scientists have suggested that by simply supplementing the grazing diets of cattle and sheep with higher quality feeds, emissions from livestock farming could be reduced by nearly a quarter in the next two decades. So relatively simple changes can make a difference, but when considering the scale of our food system’s impact on the planet, something bigger might be necessary. Industrial agriculture has been our go-to system for some time, but the overuse of powerful chemical pesticides and fertilisers is resulting in degraded ecosystems that are ultimately unsustainable.
The solution to this could be agroecology, which operates under the mantra of ‘working with nature, rather than against it’, restoring biodiversity and ecosystem functions in order to ensure productivity. These principles are already being put into action. As
“Ultimately, the choices you make about your food are just as important as the diet tribe you belong to”
it stands, rice accounts for up to a third of our annual water use, but a low-water agroecological method known as System of Rice Intensification (SRI) is increasingly being used to produce rice yields up to 50 per cent larger. Water is only applied to the rice when needed, compost is used instead of chemical fertilisers, and farmers weed by hand, instead of using herbicides. Using this method, Sumant Kumar, a farmer from the Indian state of Tamil Nadu, has smashed the previous annual rice-growing record by an astonishing three tonnes. Whether it involves rice, pigs, fish or apples, agroecology is about dismantling the current system and placing power into the hands of small-scale producers and family farms. If this is starting to sound a bit too ‘eco-warrior’ for your taste, it’s worth noting that even the UN is behind this trend. “Modern agriculture, which began in the 1950s, is more resource intensive, very fossil fuel dependent, using fertilisers, and based on massive production. This policy has to change,” declared UN representative Prof Hilal Elver back in 2014, explaining that it is agroecology that holds the key to a sustainable future.
A truly environmentally friendly diet relies on major systemic changes, but individual diets also need to change. The variety of data on offer can give the impression of flip-flopping within the scientific community, but it’s more indicative of the sheer complexity of the subject – not to mention the competing interests of stakeholders in the food industry. In fact, certain trends are clear.
Headlines about the evils of lettuce and veganism
“A truly environmentally friendly diet relies on major systemic changes, but individual diets also need to change”
saving the world may seem misleading, but it would be disingenuous to pretend that farming animals isn’t a problem. People in the West are eating too much meat, and as countries like China and India become wealthier, their demand for it is increasing. Dr Rajendra Pachauri, ex-chairman of the UN’s Intergovernmental Panel on Climate Change called for one meat-free day a week as a way of personally making a difference, and this seems like a good place to start. Other sensible suggestions include choosing fish from sustainable or certified stocks, buying vegetables that store well, and avoiding food waste. The kind of mass switch to veganism envisaged by some studies is probably unrealistic, but relatively small changes in the way we eat can produce sizeable effects. We should be at a stage where suggestions like Pachauri’s are not controversial, because while we may not have all the information, we certainly have enough to make a difference.
BELOW: Agroecology involves working with nature and putting control back in the hands of small-scale farmers
BELOW: Recently, ‘dumpster divers’ have put food waste in the spotlight by salvaging edible food from skips
ABOVE: Shelves groan with food at a Tesco distribution plant in Reading, UK RIGHT: Modern Western diets still contain too much meat
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BELOW: People who follow vegetarian diets should still be aware of how their favourite foods affect the planet
RIGHT: Red meats, like beef and lamb, have a greater impact on the planet than chicken