Agriculture is a major contributor to climate change, representing 30-40% of greenhouse gas emissions (GHGE) globally, and about 10% in the US. Individual dietary choices contribute to this problem by influencing what gets produced. Our research addresses the environmental impacts of individual food choices in the US and their implications for diet quality. We developed an approach to link environmental impacts of foods to 24-hour recall data on adult diets reported in the 2005-2010 National Health and Nutrition Examination Survey (NHANES). We constructed a distribution of the carbon footprint of 1-day diets by ranking diets from low to high impact. Those in the top quintile (i.e. high impact diets) had a carbon footprint close to eight times that of the bottom quintile. Shifting the top quintile diets to the mean resulted in a significant overall reduction in national GHGE. After scaling for energy intake, we examined the differences in food and nutrient content, and overall diet quality of these high and low-impact diets. The bottom quintile (i.e. low impact) diets scored better on vitamin E, fiber and saturated fat, but not on calcium, vitamin D, and potassium. Overall diet quality as measured by the Healthy Eating Index was better in the low impact group. These results suggest that food patterns with lower carbon footprints have a better overall diet quality and are more nutritious on several key dimensions. Our analyses highlight the importance of utilizing individual dietary behaviors rather than just population means when considering diet shift scenarios and set the stage for further policy and scenario simulations aimed at aligning environmental and nutritional outcomes.
Explain what is meant by a carbon footprint and how to calculate it for specific foods.
Describe the relationship between dietary choices and greenhouse gas emissions from food in the US context.
Explain the link between the GHGE of a diet and its overall nutritional quality.
Diego Rose, PhD - Professor, Tulane University, School of Public Health and Tropical Medicine
Diego Rose is Professor and Head of the Nutrition Section at Tulane University's School of Public Health & Tropical Medicine. His research explores the social and economic side of nutrition problems, focusing on nutrition assistance programs, food security, and the food environment. He has studied disparities in access to healthy food in New Orleans and the influences of the neighborhood retail food environment on dietary choices and obesity. His latest research project examines the environmental and health impacts of US dietary choices. Prior to joining the faculty at Tulane, he worked for USDA’s Economic Research Service on domestic food assistance policy and in Mozambique and South Africa on food security and nutrition. He began his nutrition career as the director of a local agency WIC nutrition program in a farmworker clinic in rural California. Dr. Rose holds degrees from UC Berkeley in nutritional sciences (BS), public health nutrition (MPH), and agricultural economics (PhD).
Martin Heller, PhD - Senior Research Specialist, University of Michigan, School for Environment and Sustainability
Martin Heller is a senior research specialist with the Center for Sustainable Systems (CSS) at University of Michigan. His most recent research interests involve evaluating the environmental impact of dietary choices and food waste, and combining nutritional information with environmental assessments of food and diet. A project with nutritionists at Tulane University will provide the first linkage between food environmental impacts and NHANES datasets. He has conducted life cycle assessment studies of short rotation woody biomass energy crops, a plant-based meat alternative “burger”, a large-scale vertically integrated US organic dairy, and as part of an international team, spatially-explicit study of US dairy production. He also developed a seminal report on Life Cycle-Based Sustainability Indicators for Assessment of the U. S. Food System. He received a BS in chemical engineering from Michigan State and a PhD, also in chemical engineering, at the University of Colorado at Boulder.