Need another reason to eat healthy? As most vegans already know, healthy eating isn’t just good for your body, it’s good for the environment, and a new study has broadly quantified how our diets effect our planet.
Paul Behrens, a researcher at the University of Leiden, in the Netherlands, just published his analysis in the Proceedings of the National Academy of Sciences (http://www.pnas.org/cgi/doi/10.1073/pnas.1711889114). He wanted to study what could happen if people in 37 different countries followed the dietary recommendations of their own governments, and to determine how following this advice might affect the environment. Producing foods, after all, has profoundly altered the planet, and those impacts can vary a lot, depending on which foods people demand.
Specifically, he looked at three ways the environment is affected by our diets — greenhouse gas emissions, land use and eutrofication, which is the addition of nutrients to water sources that can lead to toxic algae blooms and lack of oxygen in the water. Eutrofication is usually caused by the discharge of animal waste and plant fertilizer. In general, he says, following your country’s dietary guidelines would be good for the planet. Greenhouse gas emissions would fall, waterways would suffer less pollution from fertilizer, and less land would be required to feed people.
To come to this conclusion, Behrens turned to Exiobase, a massive input-output database that represents the entire world economy. It allowed him to track not only the environmental cost of growing and raising the various types of food we consume, but also the cost of the machinery involved in the production of that food, and the cost of getting it into our supermarkets and eventually onto our plates.
The database also takes into account that some countries are more efficient at producing food than others. For example, growing tomatoes in England takes more energy than growing them in Spain, where it is warmer. Similarly, a steak from a grain-fed cow in England has a smaller environmental footprint than one from a grass-fed cow in Australia.
In broad strokes, he found that the wealthiest countries would lower their environmental impact if their citizens followed nationally recommended diets, primarily because most of these recommendations call for a significant reduction in the amount of meat citizens consume.
The study found that if citizens in 28 high-income nations like the United States, Germany and Japan actually followed the dietary recommendations of their respective governments, greenhouse gases related to the production of the food they eat would fall by 13% to 25%.
At the same time, the amount of land it takes to produce that food could drop by as much as 17%.
Although in poorer countries like India and Indonesia the environmental impact would go up (mostly because the nationally recommended diets call for more calories than many citizens consume in those countries), the overall effect of everyone following their nationally recommended diets, would be a decrease in greenhouse gases, eutrofication and land use.
In most countries, shifting to the recommended diet would mean eating less meat, poultry and eggs. That means, in turn, less land required to grow the feed for animals, lower greenhouse gas emissions, and less water pollution. This is especially true of Brazil and Australia, where people eat lots of beef.
“In general, meat is worse than other types of food because every time something eats something else, you get a loss of energy,” Behrens said. “Eating any animal is going to have more of an impact compared to other food groups.”
In the United States, the official dietary guidelines do not explicitly call for a reduction in meat consumption. The amount of meat, poultry and eggs that the guidelines recommend, however, is generally lower than what Americans — at least adult men — currently consume. The guidelines call for an even bigger reduction in sugar consumption. All of this would mean less pollution, and more land available for nature.
Behrens says only a handful of countries even mention the potential environmental benefits of following their dietary recommendations. He thinks that’s a mistake. “It’s another reason to shift to a healthier diet,” he says.
The last time the U.S. revised its dietary guidelines, several of the scientists involved in the effort tried to do exactly that, but ran into fierce criticism from Congress. Lawmakers attached a “directive” to a spending bill instructing the Department of Health and Human Services to disregard environmental considerations when drafting its dietary advice, and the HHS complied.
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