Eating healthy can save money and also cause less greenhouse gas emissions than most people's current food choices, according to a new global study that examined food costs, nutrition, and climate impact around the world.
Led by researchers from the Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy at Tufts University , the study identified the locally available food items that would meet basic nutritional needs with the absolute lowest possible level of greenhouse gas emission and the lowest monetary cost, and compared those diets with foods actually consumed. The findings, which were recently published in Nature Food, challenge the widespread assumption that climate-friendly healthy eating requires paying more for premium products.
"People can't see or taste the emissions caused by each food, but everyone can see the item's price—and within each food group, less expensive options generally cause less emissions," said Wiliam A. Masters , senior author and a professor at the Friedman School.
As governments and international organizations explore how to cut food system emissions without worsening food insecurity, the findings address a potential win-win: healthy diets that are both cheaper and more climate friendly.
For the study, Masters and his co-investigators sought to identify which foods would be the most sustainable way to meet nutritional requirements, based on the Healthy Diet Basket targets used for global monitoring by U.N. agencies and national governments around the world.
The team analyzed three kinds of data about each food item: its availability and price in each country, how much of each country's food supply it accounted for, and the global average greenhouse gas emissions associated with that product. For each country, they modeled five diets: the healthiest diet with the lowest emissions, the healthiest diet at the lowest cost, and three versions of diets based on the most commonly consumed foods.
"In general, choosing less expensive options in each food group is a reliable way to lower the climate footprint of one's diet," said Elena M. Martinez, one of the study's lead authors, who completed the work as a doctoral student and postdoc at the Friedman School. "This new study extends that to the extremes, asking which items could meet health needs with the smallest possible climate footprint," she added.
In the reference year of 2021, a healthy diet using the most commonly consumed products in each food group emitted 2.44 kilograms of CO₂-equivalent emissions per person per day and cost a global average of $9.96. In contrast, the benchmark diet to minimize climate harms would have emitted only 0.67 kilograms and cost $6.95. A healthy diet designed to minimize monetary cost would have emitted 1.65 kilograms and cost $3.68. A third scenario that blended the most commonly consumed products with lower-cost healthy choices fell in between, costing about $6.33 per day and producing 1.86 kilograms of emissions—still well below typical diets, though not as low as the cheapest or lowest-emission options.
In most food groups, the lowest cost options are also least emitting because they generally use less fossil fuels and cause less land-use change. But at the extreme end of low costs and low emissions there are tradeoffs in two important food groups: animal-source foods and starchy staples.
Among animal-source foods the most inexpensive option is often milk, for which CO₂-equivalent emissions are much lower than beef and other meats. But fish such as sardines and mackerel have even lower emissions at an intermediate level of cost per calorie.
Among starchy staples, rice is often the least expensive option in countries where wheat or corn would be the lowest-emission products. However, emissions for rice are higher than the slightly more expensive wheat or corn, researchers said, primarily because of the methane emitted in flooded rice paddies. That microbial methane causes rice to have higher emissions even though the food is less expensive.
Researchers hope these findings help consumers, food companies, and governments shift priorities toward foods that meet health needs in more sustainable and affordable ways.
"There are situations where reducing emissions costs money, because it involves investment in new equipment and power sources," said Masters. "But at the grocery store, frugality is a helpful guide to sustainability. Most people can reduce emissions by choosing less expensive options from each food group, with important exceptions at the extremes of low-cost diets due to methane from dairy and rice."
Citation: Research reported in this article was conducted as part of the Food Prices for Nutrition project and the Innovative Methods and Metrics for Agriculture and Nutrition Actions project, both funded by the Bill & Melinda Gates Foundation and the United Kingdom government. Complete information on authors, methodology, limitations, and conflicts of interest is available in the published paper.
Disclaimer: The content is solely the responsibility of the authors and does not necessarily represent the official views of the funders and their institutions.
