Making diets more sustainable could be easier than we think

Replacing one serving of beef per day with a climate-friendly alternative would cut a diet’s carbon footprint by up to 48%, according to a new study. Researchers used real-world data to calculate the difference of swapping one high-impact food item for a more sustainable option, estimating emissions and water consumption of each. They found that this simple swap could make an important difference in our struggles against climate change. 

Image credit: Flickr / Sue Thomson.

Food systems are a big driver of the climate crisis, accounting for a third of global greenhouse gas emissions. Moreover, about 70% of the global freshwater consumption goes to agricultural production. Consumer demand is largely behind this trend, with big differences in emissions and water consumption between food types.

Previous studies showed that changing current diets could reduce emissions by up to 50%. Still, dietary change is difficult. Diets are complex and habits are hard to break, and people don’t like being told what they should or shouldn’t eat. But there are ways to convince people to shift towards more sustainable options. One strategy is taking simple steps that are easy to understand and implement — like for instance changing just one component of the diet instead of doing an altogether new diet.

With this in mind, researchers from Tulane University and the University of Michigan decided to study dietary shifts to improve sustainability with a simple strategy. The goal was to identify the foods with the biggest negative environmental impact, find substitutes that are culinary and calorically equivalent, and assess the differences if individuals change just one item of their diet. 

“We studied the potential impact of a simple substitution, one that does not reduce meat consumption, per se, but rather just beef consumption. Granted, there will be many consumers who would still resist such a dietary shift. But by keeping it simple, this approach will be easy for individuals who are motivated to change their diet,” the researchers wrote. 

Diets and the environment

Using data from a survey of what more than 16,000 US citizens eat in an average day, the researchers found that around 20% have at least one serving of beef in a day – the item with the highest environmental impact. If they swapped one serving of beef, for example for turkey, emissions would drop by 48% and water-use impact by 30%.

“People can make a significant difference in their carbon footprint with very simple changes—and the easiest one would be to substitute poultry for beef,” lead author Diego Rose. said in a statement. “The changes needed to address our climate problems are major. They are needed across all sectors and along all levels of human organization.”

Rose and the researchers also looked at how such change would alter the environmental impact of all food consumption in the US in a day. If just 20% of Americans who eat beef switched to something else just for one meal, this would cut the carbon footprint of all diets by 9.6% and reduce water-use impacts by 5.9%. Worldwide, around a third of our emissions are related to agriculture.

While replacing beef had the largest impact, the researchers also measured what would mean to change other food items. Swapping a serving of shrimp for cod would cut emissions by 24%, and replacing dairy milk for soy milk would bring down emissions by 8%. But not all the culprits are meat — the biggest reduction was for changing asparagus for peas, resulting in a 48% decrease. 

The study was published in the American Journal of Clinical Nutrition. 

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