- Humans’ food systems account for around a third of global greenhouse gas emissions.
- Consequently, if a person changes the foods they eat, they could reduce their carbon footprint.
- However, wholesale dietary changes may be one step too far for some people.
- In the present study, researchers found that substituting particular food items — rather than whole diets — can still significantly reduce an individual’s carbon footprint.
In a new study, researchers have found that a person can potentially reduce their carbon footprint significantly by substituting particular food items — in particular, beef.
The research, which appears in the American Journal of Clinical Nutrition, may motivate people to adapt their diet since it does not indicate a need to make wholesale changes to what they cook and eat.
Researchers have found that human food systems cause around one-third of global greenhouse gas emissions. Greenhouse gases are a key driver of global heating, which threatens ecosystems and biodiversity, as well as human health.
Individuals can reduce their contributions to greenhouse gas emissions and global heating by changing the types of food they consume.
However, some people may find changing to an entirely new diet challenging, particularly if they have never prepared or eaten the foods the new diet requires.
The researchers behind the present study wanted to see if making a minor change — for example, substituting a single food item in a person’s diet — could also significantly reduce their carbon footprint. If so, this might be a more feasible approach than a person changing their diet completely.
Dr. Diego Rose spoke to Medical News Today. Dr. Rose is the study’s lead author and is Professor and Director of Nutrition at the School of Public Health & Tropical Medicine, Tulane University, New Orleans.
“Previously, we developed techniques to assess the carbon footprints of self-selected American diets for large samples of individuals. When we ranked these individuals’ 1-day diets by their carbon footprints, we found that the top 20% of individuals accounted for an outsized share (46%) of the total impact.”
“We wanted to know what was driving these higher impact diets, so we drilled down into the individual diets, looking at each item they ate on a given day. In many cases, we saw that just one item in the diet turned an otherwise average diet into a high-impact diet.”
“This item was typically a beef item, and we noticed that by substituting it for a less impactful animal food — say, chicken — the overall impact of the diet would be much less.”
– Dr. Diego Rose
“That’s when we decided to study this more rigorously,” added Dr. Rose.
To do this, Dr. Rose and his colleagues drew on data from the National Health and Nutrition Examination Survey (NHANES)Trusted Source between 2005–2010. They included data from 16,800 18 years or older participants who had given information on a 24-hour dietary recall to interviewers.
The researchers then looked at the daily reported greenhouse gas emissions and water scarcity footprint.
With this information, the researchers could then identify food items that contributed the most to the adverse effects of a person’s diet and propose substitute items that might substantially reduce these adverse effects.
The researchers found that beef had the most significant adverse environmental effect. Approximately 20% of the participants ate beef at least once a day.
If the participants placed their beef consumption for another type of meat, such as turkey, they would reduce the greenhouse gas emissions associated with their diet by 48%. This change would also reduce the participants’ water scarcity footprint by 30%.
MNT spoke to Dr. Rosalind Fallaize, a lecturer in Nutrition and Dietetics at the University of Hertfordshire, Hatfield, United Kingdom. Dr. Faillaize said it was important to consider both climate change and health impacts, as the study does. However, she also highlighted that it is also important to consider the costs of switching food items.
“The analysis shows us that small dietary substitutions — [that is,] swapping beef [for] pork [or] poultry products — can reduce the environmental impact of our diets while maintaining overall diet quality. This study uses a large [United States] dataset and robust methods. It is great to see the combined consideration of the environmental impact and diet quality.”
“The paper considers a measure of diet quality — the Healthy Eating Index — to evaluate the dietary impact of the changes, ensuring that substitutions do not negatively impact this. [However,] it would be interesting to explore the impact of these changes at the micronutrient level, that is, vitamins and minerals — for example, beef contains more vitamins B12 and folate than poultry.”
“An aspect which is sometimes overlooked in this area of research is the material cost of making dietary changes — for those experiencing food poverty, cost is a key barrier. It’s important that [we consider this] when promoting more sustainable diets so that we do not exacerbate health inequalities.”
– Dr. Rosalind Fallaize
For Dr. Rose, a strength of the findings is that they increase a person’s chances of reducing their adverse climate effects. This is because substituting a single, high-impact food item is less of a change than switching an entire diet and so more likely to happen.
“It’s pretty clear from [the] research that people will not make changes if they don’t feel they are able to make changes. This ‘self-efficacy,’ or belief in one’s ability to succeed, is at the core of behavioral change theories.”
“A simple change, especially when you’re not giving up much, is obviously easier to remember and to enact [than] complex changes. Once made, the change reinforces one’s ability to succeed, and a positive feedback loop can be created for additional changes,” said Dr. Rose.
Dr. Fallaize agreed.
“The authors cite a very important aspect of changing behavior in their paper: self-efficacy, or the belief in our own ability to perform a behavior, for example, swapping beef for pork at dinner.”
“Small substitutions are often much easier to adopt than whole diet changes [or] overhauls — [for example,] swapping from a meat-based to a strict vegan diet — so we may feel more confident in our ability to do this.”
“Substitution of beef with poultry [or] pork is also more likely to draw on the same cooking skills, removing the frequently-faced barrier of not knowing how to prepare [or] cook or incorporate new or different foods in your diet. Once this small substitution has embedded into our diet [or] lifestyle, we can then try another.”
“Ultimately, small substitutions are more likely to become lasting changes, which is the goal when trying to adopt a more sustainable and or healthier diet,” said Dr. Fallaize.
Dr. Rose said that it was getting easier for consumers to identify the adverse climate effects of their food purchases.
“This is a relatively new field, which lags quite a bit behind nutrition labeling. That said, there are new tools that are constantly being developed.”
“In France, they are developing Eco-Score, a front-of-package labeling tool that assesses [the] overall environmental impact of a food. There are some apps that can provide information on this as well, for example, GreenChoice.”
“But the overall availability of resources on this front is pretty thin. We’re in the process of developing something ourselves.”
Dr. Rose said governments had an essential role in helping consumers identify lower-impact food items.
“Governments need to prioritize research in this area, specifically the life cycle assessments of food products that are at the root of this work. They also need to support the collation of all the different studies that are done in this area into usable databases that can then be disseminated.”
“Here in the U.S., the Department of Agriculture has a long history of doing research and supporting database development on the nutrient composition of foods. This has allowed third-party developers to create diet assessment apps, which the public can then use to assess their own food choices based on nutrition.”
“There really is no reason why the same approach couldn’t be taken for assessing [the] environmental impacts of diets, other than perhaps a lack of awareness or a lack of political will,” said Dr. Rose.
In the U.K., Dr. Fallaize highlighted the One Blue Dot toolkit developed by the Association of UK Dietitians as a valuable resource for consumers interested in lowering the adverse environmental effects of their diet.
Article by: Written by Timothy Huzar on January 19, 2022
— Fact checked by Alexandra Sanfins, Ph.D.