Small Change Can Make Diet More Planet Friendly
Food production often is singled out as an important contributor to climate change, with some estimates placing it at about one-quarter of carbon emissions globally. According to a study examining the real-world diets of thousands of people in the United States, the substitution of one food each day could greatly reduce the carbon footprint.
“We found that making one substitution of poultry for beef resulted in an average reduction of dietary greenhouse gases by about a half,” says lead study author Diego Rose, PhD, a professor and director of nutrition at Tulane University.
Rose presented the research at Nutrition 2019, the American Society for Nutrition annual meeting, recently held in Baltimore.
“To our knowledge, this is the only nationally representative study of the carbon footprint of individually chosen diets in the US,” Rose says. “We hope this research will raise awareness about the role of the food sector in climate change and the sizable impact of a simple dietary change.”
The new study is based on diet information from more than 16,000 participants in the 2005–2010 National Health and Nutrition Examination Survey. A portion of this survey asked participants to recall all the foods they consumed in the previous 24 hours. The researchers used this information to determine which foods had the highest greenhouse gas emissions and to calculate a carbon footprint for each individual diet.
They found that the 10 foods with the highest impacts on the environment were all cuts of beef and that about 20% of participants reported consuming one of these high-carbon foods. Using simulation, the researchers calculated a new carbon footprint for each diet by replacing beef with the closest related poultry product. For example, a broiled beef steak was replaced with broiled chicken and ground beef with ground turkey. Each substitution was performed only one time for each person who consumed one of the high-carbon foods.
Animal foods are known to contribute more to greenhouse gas emissions than plant foods. Ruminant animal foods such as beef and lamb have particularly high carbon footprints because cows and sheep also release methane gas.
“Our simulation showed that you don’t have to give up animal products to improve your carbon footprint,” Rose says. “Just one food substitution brought close to a 50% reduction, on average, in a person’s carbon footprint.”
The researchers plan to expand this research, which focused on dietary greenhouse gas emissions, to include other environmental impacts such as water use.
Although not the subject of this study, they point out that food waste and overeating also increase the carbon footprint of our diet. Thus, in addition to eating low-carbon foods, better meal planning and eating of leftovers can also help reduce the carbon footprint.— Source: American Society for Nutrition