Small diet swaps can improve quality and reduce carbon footprint, researchers flag

01 Nov 2023 --- Substituting beef with chicken or cow milk with plant-based milk could reduce the carbon footprint from food of the average US citizen by 35% and boost the quality of diets, according to a new study by scientists at the Stanford University and the Tulane University, US.

“Many people are concerned about climate change and want to know what they can do to reduce their personal carbon emissions,” Dr. Anna H Grummon, assistant professor of pediatrics at the University of Stanford, US and one of the study’s co-authors, tells Nutrition Insight.

“One place to start is with the foods we eat. Our findings suggest that small changes to what we eat can have big benefits.”

The study published in Nature Food used dietary data from a nationally representative sample of 7,753 US children and adults to identify easy and actionable dietary substitutes and simulate their impact on dietary carbon emissions and quality.  According to Grummon these changes are about replacing similar foods with one another, rather than giving up anything entirely.

Environmentally-friendly substitutes 
The study identifies four food groups: protein, milk and dairy, mixed dishes and beverages. The authors identified a range of possible substitutes for each group, from 79 in beverages to 180 in mixed dishes. They set out to determine whether simple dietary swaps systematically identified across a range of food groups could yield environmental and health benefits. 

Grummon highlights three simple types of substitutions anyone can do that would make a notable impact on carbon footprint.  

“First, replace beef with chicken or vegetarian options when choosing an entrée or main dish. For example, choosing a chicken or bean taco instead of a beef taco.”

The second swap she outlines is replacing juice with whole fruit, suggesting opting for an apple instead of apple juice.

The third is replacing dairy products with non-dairy alternatives, such as substituting cow’s milk with soy or almond milk.

The case against red meat 
The study finds that a person who makes protein substitutions would lower their food-related carbon footprint by 3.79 kg of CO2 on average, a 50.2% reduction and someone who would make a mixed-dish substitution would reduce it by 3.5 kg of CO2 or 52.6%. 

“The replacement of beef with poultry would have the greatest impact, by far and away,” highlights co-author Dr. Diego Rose, professor and director of nutrition at Tulane University, New Orleans, US. 

At the same time, Grummon underscores: “These changes are about replacing similar foods with one another – you don’t have to give up red meat entirely, for example, but you can make a difference by swapping out red meat for chicken or plant-based protein as much as possible.” 

Meanwhile Rose argues: “While the small changes approach implies that you don’t have to give up foods entirely, you only make a difference in your dietary carbon footprint when you make the substitution.”

Balanced diets with reduced consumption of meat were outlined as one of the key elements to slowing down carbon emissions and slowing the rise of global temperatures, according to the Intergovernmental Panel on Climate Change. 

Improving personal nutrition 
The environmentally conscious swaps explored in the study could improve the general population’s dietary quality by four to 10%, with some benefits being projected regardless of demographic characteristics such as age, gender or ethnicity. 

“In general, we saw that the substitutions would improve our consumption of seafood, plant protein and healthy fatty acids and decrease our consumption of saturated fat. We also saw improved fiber, folate and potassium,” says Grummon. The environmentally conscious swaps explored in the study could improve the overall dietary quality of Americans by four to 10%.

She underscores the importance of including dietary data for children in the study, since “the foods we eat in childhood often become foods we eat throughout our lives — that is, our food choices ‘track’ from childhood to adolescence and into adulthood.”

“This means that encouraging healthy eating among children can have extra benefits, since those who have healthy diets as children are also more likely to have healthy diets as adults.”

Another recent study by the University of California, US, also linked healthier food consumption to a lower carbon footprint. This research compared the carbon footprint of six popular diets: the standard American, keto, paleo, Mediterranean and climatarian diets. 

Industry impact 
Grummon further argues that the easy swaps identified in the study should be taken on board by the food industry. “Restaurants and food manufacturers can consider making ingredient swaps —  like replacing beef with chicken in an entrée, or trying more plant-based proteins.”

“Another option is to make lower-carbon foods more accessible to people, so it’s easy for consumers who want those foods to find them,” she says. 

Rose concludes: “The food industry is sensitive to consumer demands, so if consumers eat less food, those signals will work their way back through the supply chain, and eventually producers will produce less of a food. That is how impacts will be reduced — less production of high-impact foods.”  

By Milana Nikolova