By Eleanor Ball
It is a common assumption that as humans eat healthier, the environment will be healthier, too. However, a paper recently published in Nutrition Journal argues that the link between diet quality and environmental sustainability may be more nuanced than previously thought.
In order to analyze this connection, the researchers got information on the diets of thousands of Americans by using data from the National Health and Nutrition Examination Survey (NHANES) 2005-2016. This is a continuous survey maintained by the National Center for Health Statistics (NCHS), wherein participants complete a 24-hour dietary recall about what they’ve eaten recently in order to provide an approximation of what they generally eat. This is the part of the NHANES data the researchers used. Using NHANES data means their conclusions are based on what people really eat, not hypothetical diets or standards, so their arguments should have more practical applications. To be clear, this paper is not a measure of the environmental impacts of vegetarianism vs eating meat. In this study, “higher diet quality” basically means eating healthier, such as consuming more fresh produce, whole grains, and nuts. “Lower diet quality” means consuming more foods such as saturated fats, sodium, and sugar-sweetened beverages.
The researchers broke down the meals reported by survey participants into their component foods and ingredients, then calculated different aspects of the carbon footprint of each meal by using a combination of statistical models and information from other Federal databases. Across the board, they found that higher diet quality was associated with greater total food demand, retail loss, and consumer waste. However, the impact on other environmental issues, such as the use of pesticides and irrigation water, seemed to vary with how they measured how healthy the NHANES diets were.
One of the tools used to measure diet quality was something called HEI-2015, which is an index that measures adherence to the Healthy Eating Patterns of the 2015-2020 Dietary Guidelines for Americans. The other tool used was AHEI-2010, which is based on a collection of epidemiological evidence linking specific foods to chronic disease. Greater diet quality according to the HEI-2015 score was associated with greater use of pesticides and irrigation water, and diet quality did not seem to impact fertilizer nutrients. However, when the same data was analyzed using AHEI-2010, greater diet quality was associated with lower use of fertilizer nutrients, and diet quality did not seem to have an impact on pesticides and irrigation water. In short, using AHEI-2010 indicated a correlation between healthier diets and decreased or similar use of agricultural resources, but using HEI-2015 associated healthier diets with environmental trade-offs.
This is not because the data or these tools are unreliable or wrong; it is simply because these tools were built with different approaches to measuring healthy diets. However, they have both proven accurate at predicting chronic disease risk based on diet, so they can both correctly assess the effects of diet on health. Comparatively, AHEI-2010 is stricter with fruit and meat consumption and less strict with dairy consumption than HEI-2015. This goes to show that when assessing headlines and news stories, it is important to think critically about the evidence being presented. Is the story simply picking out one fact from a web of complicated information and spinning that to be the whole truth? Is there more nuance being hidden here that could change the meaning of the story?
Of course, eating unhealthily is not the way to save the planet. Instead, this study indicates that when we approach diet and environmental policies, efforts to increase healthy eating may need to go hand-in-hand with efforts to decrease food waste. At GW, we’ve seen an example of this with the food service Last Call for Food. They’ve partnered with local restaurants such as Founding Farmers and Beefsteak to offer excess, unsold meals that would normally be thrown away at a heavily discounted price. They’re able to make eating healthily on campus affordable and reduce food waste at the same time—a goal that should be taken on by all groups when developing new food policy.
Eleanor Ball is a GW Scope staff writer and social sciences editor for the George Washington Undergraduate Review. She is a sophomore majoring in Public Health and double minoring in Sociocultural Anthropology and English. Her most recent research is a project conducted with her county health department during the summer of 2020 to study local racial disparities in the COVID-19 pandemic. At GW, she is also on the boards of the GW Shakespeare Company and the Student Theatre Council.
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