Following government healthy eating guidelines could cut an individual's carbon emissions by almost a third, a new study has found
One objection to environmentally friendly diets is that by limiting specific sources of key nutritients, such as fish and dairy, people can risk undermining individual health even as they benefit the health of the planet.
This argument - long contested by those who espouse a more plant-based diet - was further undermined this week by a new study analysing the environmental impact of the government's official dietary advice, which concluded that it not only extends people's lifespans, but also helps curb greenhouse gas emissions across society.
Led by the London School of Hygiene and Tropical Medicine (LSHTM) in collaboration with the University of Oxford, the research found that the more the average person adopts the government-backed Eatwell guidelines, the more they reduced their diet's environmental impact.
Analysing nine of the government guidelines, experts found someone who followed all of them would reduce their carbon dioxide emissions by almost a third compared to someone who followed just two.
The environmental gains mirror the benefits to human health, with those following the guidelines potentially reducing their chance of premature death by seven per cent, the study found.
The most significant benefits for both individual and planetary health accrued from the same change in behaviour, the study found: switching meat for vegetables.
The Eatwell guidelines state that "most of us still are not eating enough fruit and vegetables. They should make up over a third of the food we eat each day". As such they urge people to "eat less red and processed meat like bacon, ham and sausages", advising that "pulses, such as beans, peas and lentils, are good alternatives to meat because they're lower in fat and higher in fibre and protein, too."
The guidance chimes with the advice of the world's climate bodies, which warn that - due to a range of factors including changes to land use, methane emissions, and resource inefficiency - it is unsustainable for people to continue eating the quantity of meat they currently do in the world's richest countries.
The UK's Committee on Climate Change suggested earlier this year the UK would need to cut meat and dairy consumption by a fifth if the country is to meet its net zero emissions targets, pointing out that the land used for livestock at the moment will be needed for reforestation and other carbon-storing schemes.
Another recent study concluded UK greenhouse gas emissions could be cut by more than eight per cent if everyone in the country swapped just one red meat meal for a plant-based dish every week.
The LSHTM study reinforces these conclusison, suggesting that simply following NHS guidelines for healthy eating would make a significant difference to people's carbon footprints.
"Our study demonstrates that the Eatwell Guide forms an effective first step towards more healthy and sustainable diets in the UK," said Dr Pauline Scheelbeek, assistant professor in nutritional and environmental epidemiology at the London School of Hygiene & Tropical Medicine (LSHTM) and the study's lead author.
"Further adherence to the guidelines would not only result in population health benefits, but is also associated with lower environmental footprint due to reduced greenhouse gas emission."
The government guidelines were first published in 2016. They recommend people eat at least five portions of fruit and veg a day, base meals on starchy carbohydrates such as potato, bread, rice or pasta, and drink between six and eight glasses of water everyday.
The advice also recommends small amounts of dairy alongside sources of protein, including at least two portions of fish a week - advice that contradicts the conclusions of some ocean campaigners, who have argued for a "radical reduction" in the amount of seafood that is currently consumed.
The Eatwell guidelines were not specifically designed with sustainability considerations in mind and as such Scheelbeek noted that "more transformational dietary shifts than those recommended in the Eatwell Guide will be necessary if we want to meet the Paris Agreement targets".
"The Eatwell Guide does not specifically target environmental sustainability of diets," she said. "We therefore need to investigate ways to further reduce environmental footprints of our diets in ways that would be culturally acceptable and could be implemented by the UK population."