by Brittany Patterson: U.K. researchers find changed diets could substantially cut greenhouse gas pollution and benefit health…
Cut back on the beef, dairy, sweets and savory snacks, but feel free to munch away on more fruits, vegetables and cereals, if you’d like a more climate-friendly and healthy diet, according to recent research conducted by the London School of Hygiene and Tropical Medicine.
The changes—which the authors note are ultimately “relatively minor” and “realistic”—could cut greenhouse gas emissions by 40 percent. It should be noted the studies were focused in the United Kingdom.
It may seem straightforward, but James Milner, a lecturer in the department of social and environmental health research at the London School of Hygiene and Tropical Medicine and one of the co-authors of the research, said the goal of this work was not to ask “what if” questions related to changes in diets and how that could affect emissions, but instead map current consumer behavior to determine where changes could be made that wouldn’t be radically different.
For example, a large body of research has found switching to an entirely vegetarian diet would make a huge difference on the carbon footprint of our food system—the Climate Change, Agriculture and Food Security research program reports that if the global population were to reduce or cut its meat intake, it would halve the cost of mitigation actions needed to stabilize carbon dioxide levels to 450 parts per million by midcentury—but for many people that is not in the cards.
“This is interesting but in reality most people somewhere like the U.K. simply don’t want to become vegetarian,” Milner said in an email.
Even if the average U.K. citizen were to fall in line with dietary guidelines set forth by the World Health Organization (which most do not), the study estimates there would be a 17 percent reduction in greenhouse gas emissions.
For those not concerned about the parts per million of CO2 produced by the food they buy, a second paper using the same data calculated the health impacts of altering diets and concluded a switch to WHO guidelines would save almost 7 million years of lives lost prematurely in the United Kingdom over the next three decades.
On an individual level, the average life expectancy would increase about 12 months for men and four months for women.
“We wanted to model the health impacts because this would help us to understand the trade-offs between benefits for public health, benefits for the environment, and the likely public acceptability of the modeled diets as we progressively reduced the emissions,” Milner said.
The researchers collected data from 1,571 food diaries completed by adults for four days in the United Kingdom to model the average diet and tweak it to still be appetizing but reduce emissions. On the health side, researchers modeled the outcomes from dietary changes on stroke, type 2 diabetes, heart disease, diet-related cancers and life expectancy.
Milner said the most surprising part of the research was how substantial the benefits to both health and emissions could be, without making radical changes to diets.
Healthier diets cut developed country CO2 emissions
While eating more fruits, vegetables and cereal is the main takeaway, the researchers did find some fruits and vegetables were more emissions-friendly than others. For example, tomatoes are fairly emissions-intensive, the study notes.
“One thing which was interesting was that to achieve really large GHG emission reductions, it’s better to make up your total fruit and vegetable consumption with a greater proportion of vegetables,” Milner said, but added that’s because most vegetables tend to be associated with lower emissions. “We also found a health benefit associated with this. However, it’s important to note that this results is only based on averages—there is a lot of variation within each group [fruits and vegetables]. I certainly wouldn’t want to suggest that people shouldn’t eat fruit!”
Another significant opportunity to effect change on food-system-related greenhouse gas emissions is to decrease food waste.
More than 30 percent of all food-related emissions in the United States are from uneaten food and spoiled food being tossed out, said Gregory Keoleian, director of the Center for Sustainable Systems at the University of Michigan.
In a study released last year in the Journal of Industrial Ecology, Keoleian and his colleague Martin Heller quantified the emissions of the American diet. They found the current American diet produces about 5 kilograms of CO2 per day, and 28 percent of that is due to wasted food.
“For food waste, it’s about our consumer behavior,” Keoleian said. “Don’t order more than you eat, prepare meals at home according to what your needs are, when you’re shopping don’t overbuy.”
Americans also eat too many calories, and if they are reduced, the emissions burden of our diets decreases, as well.
Keoleian and Heller found if Americans shifted to following the Agriculture Department’s dietary guidelines, they would consume less meat—good for emissions—but would drink more milk than they do currently—bad for emissions.
“Those kind of offset each other,” he added. The authors did find switching to a lacto-ovo vegetarian diet would result in a 33 percent decrease in emissions. Vegan diets are 53 percent more efficient.
‘Westernized’ diets in poor countries raise CO2 emissions
Also important to the food emissions sphere is the growing trend of “westernizing” diets in low- and middle-income countries. As incomes rise, people are spending more money on adding animal protein, sugars and processed foods into their diets, which are emissions-intensive.
A study released last November in the journal Nature estimated there will be an 80 percent increase in annual emissions globally just related to this shift in food production.
By 2050, the rise in disposable income will increase emissions from 2.27 gigatons today to 4.10 gigatons globally.
With climate change, food security and sustainability for a growing population is one of the most critical challenges facing the planet, Keoleian said, and an area where changes to the food system can have quantifiable emissions impacts.
“We need to be more efficient in how we manufacture products and grow food,” he said. “But consumers also have a role in terms of their choices.”
One challenge to changing dietary choices is finding effective ways to do it. Milner said it wasn’t a focus of the U.K. research, but an important area.
He said there are many mechanisms through which dietary changes can be garnered, like through public awareness campaigns, food processing regulations, portion size changes and tax policy, but he hopes by linking the health benefits to dietary changes, the public might take notice.
“Hopefully, research like ours demonstrates the benefits of linking public health and sustainability agendas, rather than considering each separately,” he said.