How minor dietary changes can help the environment

The food we eat on a daily basis keeps us alive, but it can also come at a high cost in terms of health and the environment—heart disease, carbon emissions, soil degradation, and so on. According to a recent study published in Nature Food, tiny changes in Americans' food choices could have large health and environmental effects.

Because many foods with a high health burden, such as processed meats or red meats, also have high environmental costs, the study claims that replacing just a few of them—roughly 10% of a person's daily calorie intake—can reduce a person's food-based environmental footprint by over 30%.

"The really wonderful thing is that foods that are better and more nutritious tend to be more environmentally sustainable, so it ends up being a win-win," says Michael Clark, a food systems researcher at Oxford who was not involved in the study.

Food production accounts for around one-fifth to one-third of all annual greenhouse gas emissions globally, thanks to growing, packaging, transporting, cooking, and often discarding it. Food accounts for roughly the same amount of greenhouse gas emissions as electricity in a typical American household. Food production causes substantial water quality and quantity issues, frequently necessitates the use of herbicides and pesticides that damage biodiversity, and results in the loss of forest and wildness when lands are converted to farmland.

"It has a big influence," says Olivier Jolliet, a University of Michigan environmental scientist and one of the study's authors. "It's like, Houston, we've got a problem, and we need to take it seriously." So yet, the US hasn't taken it seriously."

He emphasizes that solving national or global health and environmental concerns is not up to or the duty of any single person. However, insights like the ones he and his colleagues generated can assist individuals, institutions, and even governments find out where to focus their efforts in order to have the greatest impact as rapidly as possible.

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Looking at two objects at the same time

Researchers first analyzed food-related harms to discover how to lessen the harmful effects of food production and consumption on the earth and the body. However, as the global food chain changes, determining where an apple comes from, let alone its environmental impact, has become a more difficult task. Researchers at the Stockholm Environmental Institute, for example, have spent years unraveling the supply chains of products like cocoa and coffee, even when they come from the same country.

So, over the last few decades, scientists like Jolliet have developed methods for conducting "life cycle analyses" for specific items—for example, a head of broccoli or a box of corn flakes—that consider all of the steps from farm to store and assign the items a hard number indicating their environmental impact, such as an estimate of greenhouse gas emissions or water volume required for production.

Similarly, epidemiologists and public health professionals were analyzing human bodies at the same time. They looked at the linkages between food and health in great detail, figuring out how different diets and even specific foods might affect things like illness risk, overall health, and life expectancy, and assigning numerical figures to those risks.

For many years, researchers and governments separated the issues: health researchers worked on their goals, while environmental scientists focused on theirs (though as early as the 1970s, scientists were linking diet choices with planetary health). According to Sarah Reinhardt of the Union of Concerned Scientists, a specialist on food systems and health, "it has become increasingly evident that what we eat is intricately associated with planetary health."

Because of the rising demand for soy protein to feed cattle, enormous areas of the Amazon are deforested every year to make room for new soy farms and cattle, hastening the loss of carbon-absorbing and biodiverse forest.

"Agriculture is a critical piece of the climate jigsaw, and agriculture, food, and diet are all intertwined," adds Reinhardt.

As a result, Jolliet and his colleagues devised a system that addressed both issues by examining the health and environmental consequences of individual meals.

They had previously collaborated on a large database that quantified the health consequences of dietary choices such as eating too much processed meat or not enough whole grains; the University of Michigan team converted those dietary risks into an estimate of "disability-adjusted life years," or DALYs, which is a measure of how much life expectancy someone might lose or gain by changing their actions. The researchers looked at how specific items, not just categories like vegetables, could affect DALYs, highlighting the benefits of some foods and the drawbacks of others if someone's baseline diet changed. Consuming a lot of red meat, for example, has been linked to diabetes and heart disease, whereas eating a lot of vegetables reduces the risk of heart disease.

They do warn, however, that their findings apply to the entire population, not just an individual, because each person has their own set of health concerns that may alter their susceptibility to dietary modifications.

The Michigan researchers looked examined the nutritional content of roughly 6,000 meals, including hot dogs, chicken wings, peanut-butter-and-jelly sandwiches, and beets, to get to this conclusion. A hot dog would probably add 35 minutes to one's life; most fruits would probably add a few minutes; and sardines fried in tomato sauce would probably add 82 minutes. Apple pie comes out about even in the calculations—a little lift from the apples, a little loss from the butter, wheat, and sugar.

This investigation revealed nothing particularly unusual. Processed meats, red meats, and severely processed, high-sugar diets have long been related to an increased risk of several diseases, according to epidemiologists. Researchers may rank, order, and establish a precise grasp of how various habits might affect customers by breaking down the potential consequences of so many products.

At the same time, the team assessed the environmental impact of the thousands of food items. They looked at 15 various ways the ecosystem absorbed the impact of food production, from the effects on neighboring water systems to the rare minerals required to grow or package foodstuffs to the local air pollution created by processing.

When researchers looked at both difficulties at the same time, they discovered a promising trend. Many meals that were beneficial for people's health were also healthy for the environment. Beans, vegetables (save those cultivated in greenhouses) and some responsibly farmed seafood like catfish all fell into the "green" zone, which was not surprising. Foods from the "Amber" zone, such as milk and yogurt, egg-based foods, and greenhouse-grown vegetables, helped to keep health and environmental costs in check. Beef, processed meats, hog, and lamb were among the foods in the "red" zone, which had high health and environmental costs. They calculated that a serving of beef stew has the carbon footprint of driving 14 kilometers.

Except for water use, the pattern held for most environmental indices. Nuts and fruits have numerous health benefits, but they are frequently cultivated in water-scarce areas such as California. "There are enormous consequences for water use when you talk about the meals we're eating now vs the foods we "should" be eating like nuts and fruits," Reinhardt says. "That doesn't mean we shouldn't consume more of them; it just means we need to figure out how to fix the problem."

What should we do if we can't stop eating?

For some climate challenges, there are relatively straightforward fixes. For example, renewable energy sources can already replace much of the energy needed to power buildings, cars, and more.

There is no alternative for food, but we can change what we eat. The food system's greenhouse gas emissions might be reduced by more than half if everyone on the earth ate vegan; a world of vegetarians would reduce food emissions by 44%. According to a recent research that addressed the unique thought experiment, if humans stopped consuming "food" as we know it and lived exclusively off a nutritional slurry created in a lab instead of in soil or water, we could save around 1 degree Celsius (1.8 degrees Fahrenheit) of future warming.

"What this research suggests is that even if we don't make these really substantial changes in dietary composition, we may still have pretty big wins," Clark adds. "I think that's extremely compelling, because a lot of people, for a variety of reasons, don't want to make those really large dietary adjustments."

While vegetarian and vegan diets are becoming more popular in the United States and Europe, he believes it is "absolutely ludicrous" to believe that "everyone will be eating a vegetarian diet in 30 years."

Food choices are extremely personal, influenced by culture, religion, emotion, economic considerations, and a variety of other factors. Naglaa El-Abbadi, a food, nutrition, and environment researcher at Tufts University, believes that rather than dictating, "it's far better to attempt to give options." This strategy tries to educate individuals so they may make decisions that are in line with their needs and ideals. In the end, those decisions may benefit both human health and the environment.

She emphasizes that this would require collaboration with large-scale attempts to transform industrial food production.

But, as Clark points out, what people eat on a daily basis is far from unimportant. "We don't have to all go vegan right away," he says. "Small adjustments can have a significant impact."