• Posted October 26, 2023

Even Small Dietary Changes Bring Big Benefit to the Planet

Fighting climate change could come down to choosing chicken for your burrito or using soy milk for coffee creamer, a new study suggests.

Making simple substitutions to an everyday diet can reduce the average American's food-based carbon footprint by more than 35%, according to an article published online Oct. 26 in the journal Nature Food.

"What we're looking at here is a small changes approach. What happens if somebody just changes one thing in their diet?"said senior researcher Diego Rose, nutrition program director at Tulane University School of Public Health and Tropical Medicine in New Orleans.

"What we found was that if you just made one change -- if everybody that was eating a high-carbon footprint food in those categories just made one change on a given day -- that you could really lower the overall carbon footprint,"Rose continued.

What's more, these substitutions also tended to improve the quality of a person's diet, the researchers noted.

A person might scoff at the thought of their bacon cheeseburger contributing to global climate catastrophe, but they would be wrong, Rose said.

"What a lot of people don't realize is that human food systems globally account for a third of greenhouse gas emissions,"he said.

To assess how small substitutions might help the climate, Rose's team analyzed diet data from more than 7,700 adults and children who participated in a federal health and nutrition survey.

The researchers looked at four broad food groups -- protein foods, mixed dishes, milk and dairy products, and non-alcoholic beverages -- and estimated the impact of a person substituting a high-carbon-impact food with a more environmentally friendly alternative.

Potential substitutions ranged from 79 possibilities in the beverage group to 180 in the mixed-dish group, which included meals like burritos, pastas, stir-frys and sandwiches.

The biggest improvements came from substitutions in mixed-dish and protein foods, the investigators found.

Substituting chicken or tofu for beef in a mixed dish could reduce a person's daily food-based carbon footprint by 53%, while substituting a chicken breast for a steak on the grill could reduce the footprint by 50%, the study results showed.

"If you're ordering burritos or tacos, there's so much other stuff in that dish that if you swap out the ground beef and instead put ground turkey or put chicken in there, you probably won't notice the difference, but you're definitely going to lower the carbon footprint of your diet,"Rose said.

Substitutions in milk and dairy or beverages also helped, but to a lesser extent, reducing carbon footprint by about 8%.

Those substitutions also could improve a person's overall diet, the researchers added.

"We looked at the Healthy Eating Index, which is a measure used to evaluate the overall nutritional quality of a diet, and we found that diets improved with these changes anywhere from 4% to 10%,"Rose said.

Nutrition and environmental experts agreed that moving away from beef is the dietary change that could produce the most benefits for the planet.

Grazing animals like cattle or lamb, in particular, have a large carbon footprint, Rose said.

"Those animals are amazing because they are able to eat grass and turn it into calories,"he said. "But in the process of doing that, the fermentation in their gut turns out methane gases. What that means in popular terms is that the impact of beef is 8 to 10 times that of chicken."

Producing feed for cattle also produces a lot of emissions, most notably nitrous oxide emissions from fertilizer, added Geoff Horsfield, a government affairs manager with the Environmental Working Group.

Loading your plate with fruits and veggies also will help both your health and the planet, the experts said.

"I think it starts with plants. If you want to make less of an environmental impact or less of a climate impact with your foods, make plants the star of your plate,"said Horsfield, who did not participate in the study.

"Tofu has been around for tens of thousands of years and has lower emissions than animal products,"he added. "We know things like oat milk and almond milk and soy milk are all better than their cow-based dairy counterparts for climate."

Emma Laing, a national spokeswoman for the Academy of Nutrition and Dietetics, agreed.

She noted that a majority of Americans do not meet Dietary Guidelines recommendations for fruit and vegetable intake.

"For those not meeting these recommendations, incorporating more plant-based or plant-forward practices into an otherwise varied eating pattern would be beneficial,"said Liang, director of dietetics at the University of Georgia.

"Eating a varied diet not only supports health but it also benefits the environment,"she added. "Having access to safe, nutritious and affordable foods within our food system -- while conserving resources involved in production, distribution, and consumption of foods -- are important for both our health and the planet."

More information

The World Economic Forum has more about food and climate change.

SOURCES: Diego Rose, PhD, MPH, RD, nutrition program director, Tulane University School of Public Health and Tropical Medicine, New Orleans, La.; Geoff Horsfield, BA, MPP, government affairs manager, Environmental Working Group, Washington, D.C.; Emma Liang, PhD, RDN, director, dietetics, University of Georgia, Athens, Ga.; Nature Food, Oct. 26, 2023