A comprehensive study that examined the environmental impact of vegan diets compared with vegetarianism, fish eating, and meat-eating, found clear advantages for veganism.
The study, published in the journal Nature, looked at the dietary consumption of 55,504 people in the U.K. and foods from 38,000 farms in 119 different countries, and sought to account for variations in sourcing and other factors that impact the environment. It found that the environmental impact of the diets of vegans in the survey was about 75 percent less than that of heavy meat eaters for some key environmental factors, including greenhouse gas emissions and land use.
While other studies have indicated the environmental benefits of a plant-based diet using more theoretical models and averages around the impacts of food production, this report sought to incorporate the actual dietary consumption of the participants as well as differences among various agricultural production methods and locations around the world. It also drew clear distinctions between each of the different dietary regimens.
“Despite substantial variation due to where and how food is produced, the relationship between environmental impact and animal-based food consumption is clear and should prompt the reduction of the latter,” the report concluded.
Reducing food waste and making agriculture more efficient through technological advances will not be enough to reduce the impact of the global food system on the environment, according to the report, which called for “major dietary changes.”
In addition to greenhouse gas emissions and land use, other factors, including water use, biodiversity, and eutrophication were also analyzed. (Eutrophication occurs when a body of water becomes overly enriched with nutrients, often due to intensive agriculture, resulting in effects such as algae blooms and harm to marine life.) The report found that each of these areas were also significantly less impacted by vegan diets than by diets high in meat consumption.
In addition, the impact on the environment generally increased based on the amount of meat products consumed. Heavy meat eaters (100 or more grams per day) had a bigger environmental impact than moderate meat eaters, and those who consumed relatively little meat (less than 50 grams per day) had an environmental impact that was at least 30 percent less than that of heavy meat eaters for most indicators.
Vegetarian and fish-eating diets (without meat consumption, but potentially including some animal-based products) were both more harmful to the environment than vegan diets, but overall less harmful than eating meat.
The research followed reports last year from the Harvard T.H. Chan School of Public Health and Brigham and Women’s Hospital, which showed that a healthy plant-based diet was better for the environment than a less healthy plant-based diet that includes foods such as refined grains and sweetened beverages. That research also found that red and processed meat had the highest environmental impact out of all food groups in participants’ diets. These foods caused the largest share of greenhouse gas emissions and required the most irrigation water, cropland and fertilizer.
“The differences between plant-based diets was surprising because they’re often portrayed as universally healthy and good for the environment, but it’s more nuanced than that,” said Aviva Musicus, postdoctoral research fellow in the Department of Nutrition at Harvard Chan School and corresponding author of the study.
That study, which claims to be one of the first to look at both the health and environmental impacts of various plant-based diets, was published in the November 2022 edition of The Lancet Planetary Health.
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