In a new study, researchers found eating a low-carbon diet is good both for people’s health and the planet.
They examined the carbon footprint of what more than 16,000 Americans eat in a day and found diets that are more climate-friendly are also healthier.
The research was conducted by a team from Tulane University and the University of Michigan.
Food production is a major contributor to climate change, and scientists sought to learn more about the impacts of Americans’ daily dietary choices.
In the study, the team built an extensive database of the greenhouse gas emissions related to the production of foods and linked it to a large federal survey that asked people what they ate over a 24-hour period.
The researchers ranked diets by the amount of greenhouse gas emissions per 1,000 calories consumed and divided them into five equal groups.
Then they rated the nutritional value of foods consumed in each diet using the U.S. Healthy Eating Index, a federal measure of diet quality, and compared the lowest to the highest-impact groups on this and other measures.
They found Americans in the lowest carbon footprint group ate a healthier diet, as measured by this index.
People whose diets had a lower carbon footprint were eating less red meat and dairy, and consuming more healthful foods like poultry, whole grains, and plant-based proteins.
Red meat and dairy contribute to a larger share of greenhouse gas emissions and are high in saturated fat.
Overall, diets in the lowest impact group were healthier, but not on all measures.
These low-carbon diets contained more of some low-emission items that aren’t healthy, namely added sugars and refined grains.
They also had lower amounts of nutrients because of the lower intakes of meat and dairy.
The team also found diets in the highest-impact group accounted for five times the emissions of those in the lowest impact group.
The high-carbon diets had greater quantities of meat (beef, veal, pork, and game), dairy and solid fats per 1000 calories than the low-impact diets.
Overall, the high-carbon diets were more concentrated in total proteins and animal protein foods.
One early study found that 20% of Americans accounted for almost half of U.S. diet-related greenhouse gas emissions.
The team hopes the research will help the public and policymakers recognize that improving diet quality can also help the environment.
If people reduce the amount of red meat in our diets and replace it with other protein foods such as chicken, eggs, or beans, they could reduce carbon footprint and improve their health at the same time.
The research is the first to compare the climate impact and nutritional value of U.S. diets using real-world data about what Americans say they are eating.
The lead author of the study is Diego Rose, a professor of nutrition and food security at Tulane University’s School of Public Health and Tropical Medicine.
The study is published in the American Journal of Clinical Nutrition.
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