Are more sustainable diets actually healthier?
Travelling by train. Buying pre-loved. Switching banks so you're no longer supporting one that finances fossil fuel projects.
All commendable ways of showing up in the fight against climate change.
But if you're in the market for a method of effecting change you can engage with every day, your diet is a good place to start.
Climate scientists agree, flagging that food systems contribute over a quarter of the world's planet-heating greenhouse gas emissions, thanks to the changing land use involved in meeting global food demand, as we as the emissions involved in food production.
The message is sinking in, with more than 75% of those polled by Ipsos Mori and the Food Standards Agency agreeing that it's important to buy food with a low environmental impact. But is what's good for the planet good for your health?
Do diets that support the planet's health also support yours?
That meat production (especially red meat) is a significant contributor to climate change is unlikely to come as a surprise. It's the biggest source of methane – a potent greenhouse gas (GHG) emitted via belching cows (charming), along with manure.
It drains an eye-watering amount of land and water too; 1,695 litres of water goes into making the average quarter-pounder, according to the UN Environment Programme.
It means whatever way you cut it, the environmental impact of animal foods is greater than plant-based foods. A recent Oxford University study comparing the environmental effects of the diets of over 50,000 people showed vegan diets had 30% of the environmental impact of high-meat diets. Even among carnivores, there was a 30% difference between low-meat eaters (zero to 50g a day) and high-meat eaters (100g or more a day) for most environmental indicators.
What does a sustainable diet actually look like?
And yet defining what a sustainable diet looks like is messier than a cow-filled field at lunchtime, with factors such as water and land use weighed up against cost, nutrition and accessibility.
Determining the impact of dietary changes isn't straightforward, either. Advice to eat local is misguided, with food miles a small contributor to GHG emissions.
According to Dr Hannah Ritchie, geoscientist and senior researcher at Our World in Data, what we eat matters more than food miles and packaging (the exception being air-freighted fruit and veg). With that in mind, plant foods generally have a smaller environmental footprint than animal products, with beans, tofu and nuts boasting the lowest protein carbon footprint. Other sustainable choices include reducing dairy and loading up on whole grains and greens.
An analysis by The Carbon Trust found that if everyone in the UK ate according to the Eatwell Guide (five portions of fruit and vegetables a day, prioritising whole grains and getting most of their protein from plants and sustainably sourced fish), we'd cut our GHG emissions by 45% and land use by half.
Eating this way would also reduce the risk of type 2 diabetes, heart disease and colon cancer.
As with most things, it's not all or nothing: even partly replacing meat and dairy with plants can slash emissions by 30%. So if you want a dairy latte to fuel your ethical bank search, crack on.
Three ways to improve the planet's health – and yours
1) Eat plant-based meals
Aim to have more meat-free days by swapping it for plant-based proteins such as tofu, nuts and beans.
2) Reduce your food waste
To limit waste, do an inventory before you shop, plan your meals in advance and freeze leftovers for later.
3) Moderate your dairy intake
If you choose to reduce or eliminate your dairy intake, make sure that your plant-based milk is fortified with calcium and iodine.
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