A study of the diets of more than 16,000 Americans, published today in the American Journal of Clinical Nutrition, revealed that low-carbon diets are not only good for the planet, they're also healthier.
smolaw | Shutterstock
Food production is a major contributor to climate change and it was recently estimated that the environmental pressures of food production could increase by up to 90% by 2050. The estimates are based on current population growth and increased consumption of Western diets high in red meats and processed foods,
A study published last year reported that 20% of Americans accounted for almost half of total US diet-related greenhouse gas emissions.
To scientifically assess the environmental impact of diet, researchers at the University of Michigan and Tulane University created an extensive database of the greenhouse gas emissions related to the production of different foods.
They then surveyed over 16,000 individuals of the general population in the US, asking them what they ate over a typical 24-hour period.
The scientists used the database to determine the carbon-footprint of each diet and split them into five equal groups according to the level of greenhouse gas emissions per 1,000 calories consumed.
Emission levels for the diets in the highest-impact group were five times greater than those in the lowest-impact group.
The nutritional value of each diet was also determined using the US Healthy Eating Index, a federal measure of diet quality. Nutritional value was then compared across the five environmental impact groups.
The highest-impact diets included moremeat (beef, veal, pork and game), dairy and solid fats per 1,000 calories than the low-impact diets. Overall, the high-impact diets were more concentrated in total proteins and animal protein foods.
The group with the lowest-carbon footprint was shown to have the healthiest diet, being more plant-based, which has health benefits through lowering the risks for obesity, heart disease and Type 2 diabetes. However, some of the individuals in this group ate more of some low-emission items that aren't healthy, such as added sugars and refined grains.
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,"
Dr. Diego Rose, Lead Author
Study co-author Martin Heller remarked "The good news here is that there are win-win solutions with diets that are healthier for people and the planet. 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."
Due to the complex nature of nutrition, the low-carbon diet was not healthier in all aspects. Individuals in this groups had lower intakes of important nutrients, such as iron, calcium and vitamin D, which are typically obtained from meat and dairy products.
This study is the first to compare the climate impact and nutritional value of US diets using real-world data about what Americans say they are eating.
It is hoped that the findings will help the general public and policymakers recognize that improving diet quality can also help the environment.