Gigantic study reveals the healthiest foods are the most sustainable

You don't have to choose between health benefits and sustainability.

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glacier

Rising tides and receding glaciers may seem to have little to do with what you eat. But growing research suggests how you fill your plate directly influences environmental change. New research published in Proceedings of the National Academy of Sciences connects the dots between diet, health, and sustainability, and shows the healthiest foods are also the best for the earth.

The team found that just adding one serving of certain foods helps the environment and reduces the risk of some of the most common and devastating diseases.

“Overcoming current environmental and health challenges may seem overwhelming, but there is much that we as individuals can do,” Michael A. Clark Ph.D., tells Inverse. “Choosing to purchase and consume foods that are win-wins for health and environment will be key in reversing the growing health and environmental harms that societies globally are experiencing.”

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Connecting the dots

The study is a meta-meta-analysis— combining the findings of 19 meta-analyses. The statistical technique uses data from numerous individual studies to derive a more general relationship and reduce the risk of bias in any one study. The research team, led by David Tilman, Ph.D. and Michael A. Clark Ph.D., sifted through hundreds of studies tracking the dietary patterns and health outcomes of tens of millions of people. Most of the people in the study ate a “Westernized” diet, filled with high-calorie, processed foods, as well as lots of meat and sugar.

“We thought that this approach might be tangible to individuals because it examines the potential effect of small changes to current dietary patterns, even if larger dietary transitions will likely be necessary to meet health and environmental targets,” Clark tells Inverse.

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Agriculture takes up an estimated 80 percent of the United States water supply. 

The scientists explored how consuming fifteen different food groups is associated with five health outcomes — type 2 diabetes, stroke, coronary heart disease, colorectal cancer and mortality — and five aspects of environmental degradation: greenhouse gas emissions, land use, water use, acidification and eutrophication.

“It can be easy to focus on one outcome (e.g. health) at the detriment of others (e.g. environment),” Clark says. “Showing that there are foods that are win-wins for both outcomes and others that are lose-loses helps to link, synthesize, and clarify ongoing discussions focusing on diet-related health and environmental issues.”

Diet for the future

It turns out the foods that damage the earth and our bodies are the same.

The worst offenders? Unprocessed and processed red meat, which had the strongest association with heightened risk of mortality, type 2 diabetes, stroke and heart disease. Producing red meat was also ten to 100 times worse for the environment than producing plant-sourced foods due to greenhouse gas emissions, land use, acidification, and eutrophication. 

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Red meat leads to environmental degradation and higher risks of disease, the research showed.

Consuming sugar-sweetened beverages, like soda and fruit juice, were also terrible for your health, but surprisingly, had very low environmental costs.

Adding an extra serving of dairy products, eggs, or chicken was not associated with upping or lowering disease risk. These foods have moderate environmental impacts.

You may guess the foods you want to eat more of. Adding a serving of nuts, minimally processed whole grains, fruits, vegetables, legumes, olive oil, and fish every day reduces the risk of the five diseases in question. Excluding fish, these foods also had the lowest negative environmental impacts. These foods are present in plant-heavy diets like the Mediterranean diet, a doctor’s favorite.

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The researchers compared the environmental impact and risk of disease of fifteen food groups. 

The researchers note that certain nuances can make the environmental or health impacts stronger or weaker: leafy greens are better for reducing type 2 diabetes risk than some other vegetables while frying fish can negate its positive health effects. Wild-caught fish can be less resource intensive than farm-raised fish, using no irrigation water and resulting in less eutrophication, but still threatens the overall health of marine and freshwater ecosystems. Production of wild-caught fish can result in habitat disturbance through dredging and trawling, as well as bycatch production. Global fish stocks are dramatically overfished, so consuming both farm-raised fish and wild-caught fish can be unsustainable.

It’s all about choosing foods, mosly plants, as close to their natural state as possible. “Taste the rainbow,” is an accurate suggestion if you’re talking about eating a diverse range of colorful fruits and vegetables, not Skittles.

Adding servings instead of swapping them could impact long term health, and the researchers aren’t sure how. The extra calories could lead to weight gain, so the best approach may be switching out that single serving of short ribs for spaghetti squash.

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Under pressure

Agriculture’s impact on the earth isn’t a mystery: scientific evidence shows growing our food wreaks havoc on the soil, puts water and land resources under pressure, and causes nutrient pollution that profoundly alters ecosystems and water quality. Food production jeopardizes biodiversity through habitat destruction and nutrient pollution. Agriculture threatens over seventy percent of birds and mammals already on the brink of extinction.

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Clearing land for agriculture threatens species like the bald eagle.

Eating lots of plants, whole grains, and olive oil isn’t just good for you; it’s good for the planet. And you don’t have to go vegan to create a cascade of positive health and environmental effects. Swapping one serving a day makes a difference.

Ultimately, Clark says swapping a single serving is a good start, but dietary changes might have to be more extreme to mitigate environmental issues and the crisis of non-communicable diseases like stroke, heart disease, and diabetes.

“That does not mean that we need to give up red meat, processed foods, or sugars entirely, but meeting health and environmental goals will likely require larger than one serving changes to diets for many foods.”


Editor’s Note: Thanks to a reader for pointing out that wild-caught fish, while less resource-intensive, still can threaten the overall health of a marine or freshwater ecosystem. This story has been updated with that additional nuance.

Abstract:

Food choices are shifting globally in ways that are negatively affecting both human health and the environment. Here we consider how consuming an additional serving per day of each of 15 foods is associated with 5 health outcomes in adults and 5 aspects of agriculturally driven environmental degradation. We find that while there is substantial variation in the health outcomes of different foods, foods associated with a larger reduction in disease risk for one health outcome are often associated with larger reductions in disease risk for other health outcomes. Likewise, foods with lower impacts on one metric of environmental harm tend to have lower impacts on others. Additionally, of the foods associated with improved health (whole grain cereals, fruits, vegetables, legumes, nuts, olive oil, and fish), all except fish have among the lowest environmental impacts, and fish has markedly lower impacts than red meats and processed meats. Foods associated with the largest negative environmental impacts—unprocessed and processed red meat—are consistently associated with the largest increases in disease risk. Thus, dietary transitions toward greater consumption of healthier foods would generally improve environmental sustainability, although processed foods high in sugars harm health but can have relatively low environmental impacts. These findings could help consumers, policy makers, and food companies to better understand the multiple health and environmental implications of food choices.