Diets that are better for the environment are also healthier

Based on the carbon footprint of what more than 16,000 Americans eat in a day, researchers have found that diets which are environmentally friendly are also healthier. The study is the first to compare the climate impact of foods to their nutritional value using real-world data about what Americans are eating.

“The good news here is that there are win-win solutions with diets that are healthier for people and planet,” said study co-author Martin Heller of the University of Michigan Center for Sustainable Systems.

“Big reductions in food-related emissions don’t require eliminating foods entirely: moderate shifts away from red meat and toward beans, eggs or chicken can lead to significant improvements in both health and our diet’s carbon footprint.”

Study lead author Diego Rose is a professor of Nutrition and Food Security at Tulane University‘s School of Public Health and Tropical Medicine.

“People whose diets had a lower carbon footprint were eating less red meat and dairy – which contribute to a larger share of greenhouse gas emissions and are high in saturated fat – and consuming more healthful foods like poultry, whole grains and plant-based proteins,” said Professor Rose.

The researchers developed an extensive database linking greenhouse gas emissions to the production of specific foods, and incorporated the results of a large national survey which revealed what the respondents were eating in a typical 24-hour period. Next, the team ranked diets by the amount of greenhouse gas emissions per 1,000 calories consumed and then divided them into five equal groups.

After assessing the nutritional value of foods using the U.S. Healthy Eating Index, the experts determined that Americans in the lowest-carbon footprint group ate a healthier diet. However, these diets also contained some low-emission items that are not healthy, such as added sugars and refined grains. Furthermore, the diets among this group had lower amounts of iron, calcium, and vitamin D.

The highest-impact diets had greater quantities of meat, dairy, and solid fats per 1,000 calories. Diets in this category were found to contribute to five times the amount of emissions compared to those in the lowest-impact group.

Heller concluded, “We hope these findings will help the public and policymakers recognize that improving diet quality can also help the environment.”

The study is published in the American Journal of Clinical Nutrition.

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By Chrissy Sexton, Earth.com Staff Writer