Is A Healthy Diet Good For The Planet?


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While there has been an explosion of public interest in the topics of gut health, gut healthy foods and supplements in the past couple of years, the intricate link between food, human health, and the health of the planet, the so called One Health concept has received considerably less attention.

In 2019, one of the most comprehensive reports based on the One Health concept—exploring the intricate connections among a healthy diet, sustainable food systems, and planetary health—was published in the Lancet by the EAT-Lancet Commission, a group of thirty-seven leading scientists from various disciplines and sixteen countries, co-chaired by Johan Rockstroem, from the Potsdam Institute for Climate Impact Research, and Walter C. Willett from the Harvard T. H. Chan School of Public Health. When I interviewed Willett for my book, The Gut Immune Connection, he explained “This commission was put together . . . to look at the issue of whether and how we would be able to feed a diet that is both healthy and sustainable to about ten billion people by 2050.” The findings, according to its authors, “provide the first ever scientific target” for reaching this goal.

The commission reported that the production and consumption of food in the Anthropocene—our current age, in which human activity has been the primary influence on climate and the environment—represents one of the greatest health and environmental challenges of the twenty-first century. This is not only because the world is dealing with an epidemic of chronic noncommunicable diseases related to obesity, metabolic disorders, cardiovascular diseases, and chronic brain disorder, but also because many environmental systems and processes have been pushed beyond safe boundaries.

Disturbances in food supply and consumption have resulted in 2.1 billion adults being overweight or obese and in a doubling of the global prevalence of diabetes in the past thirty years—while at the same time more than 820 million people are undernourished, 151 million children are stunted, 51 million children suffer acute malnutrition, and more than 2 billion people are micronutrient deficient.

Meanwhile, food production is the largest cause of global environmental change. Agriculture occupies about 40 percent of land around the world, and food production is responsible for up to 30 percent of greenhouse-gas emissions. It also absorbs 70 percent of our freshwater use. Experiencing the historic drought conditions in California combined with continuously rising temperatures in real time, turns these statistical numbers into daily experiences for millions of people.

To eat both healthily and sustainably, the EAT-Lancet Commission recommended a “win-win” diet, meaning there must be a safe “operating space” for food systems, defined by how much we need of specific food groups daily in order to both maintain human health and the environment—for example, one hundred to three hundred grams (three and a half to seven ounces) of fruit per day. Willett explained: “We have a lot of evidence for what a healthy diet is. If we look just at health, it points us in the direction of being largely plant-based— not necessarily all vegetarian or vegan but predominantly plant-based. Remarkably, the convergence of scientific advances in a wide range of disciplines, ranging from epidemiology, the microbiome field, metabolism, neuroscience, all the way to plant and soil science, all support the benefits of [this] diet as well.”

A recent study, published in the prestigious journal Proceedings of the National Academcy of Sciences (PNAS) a group of investigators from the University of Oxford, UK, under the leadership of Michael Clark aimed to increase the understanding of the environmental impacts of commercially available food products in order to support transitions to environmentally sustainable food systems. Using ingredient lists to infer the composition of each ingredient in commercially available foods and pairing them with environmental databases containing information about environmental impact they derived estimates of a food product’s environmental impact across four indicators: greenhouse gas emissions, land use, water stress, and eutrophication potential (harmful algal blooms, dead zones, and fish kills secondary to agricultural run off into rivers and coastal waters).

Using this approach on 57,000 (!) food products commercially available online from eight online stores, including the UK based company called Tesco showed that certain food categories can be identified that have low (e.g., sugary beverages, fruits, breads), to intermediate (e.g., many desserts, pastries), to high environmental impacts (e.g., red meat, fish, cheese). They could also show that more nutritious products are often but not always more environmentally sustainable. They identified exceptions to this trend, with foods consumers may view as substitutable can have markedly different impacts.

The authors reported that “…many Aisles at Tesco were win-wins (good for the environment and good for human health) and were more nutritious and sustainable than most other Aisles (e.g., an estimated environmental and nutritional impact below the median of all of the Aisles examined). These Aisles included, for instance, fruits, vegetables, salad, breakfast cereals, some breads, and meat alternatives (e.g., tofu, vegan sausages). Conversely, there were numerous lose-lose foods (bad for the environment and bad for human health) with nutrition and environmental impacts above the median. These foods included cheese, chocolate, savory pies, and quiches. Win-lose foods (good nutrition composition but above median estimated environmental impact) included fish and seafood, (threatened by overfishing) nuts (excessive water use), and some ready meals. Interestingly, beef and lamb also fell into the win-lose category. According to the authors (not necessarily shared by myself), “…evidence suggests that the health and nutrition impacts of beef can range from detrimental to beneficial, depending on the context in which it is consumed: studies in high-income and high-consuming contexts indicate that increasing consumption of red meat would negatively affect health outcomes, whereas red meat consumption (and, more broadly, animal-based foods) in food-insecure contexts can be integral to nutrition security. Lose-win categories (poor nutrition quality but below median environmental impacts) included sweet cakes and pies, sugary drinks (colas, squash, cordials, fruit juices), frozen desserts, and table sauces. Many of these lose-win categories included processed food products that contain ingredients with low environmental impacts but that are also
known to contribute to poor health outcomes (e.g., sugar, salt, added fats, refined grain flours).

In summary, the Clark study using a more granular analysis supported many of the conclusions reached by the EAT Lancet commission 3 years ago, pointing out the complexity of dietary recommendations. By estimating the environmental impacts of food products in a standardized way, the authors aimed to enable informed decision making by end users such as consumers and policy makers. For the average consumer, the message is clear for the win-win category of foods, which corresponds with the general recommendations of a largely plant-based diet, and for the win-lose category which highlights the negative environmental impact of several healthy foods. The question remains if the findings of these amazing research efforts will be able to transform dietary habits of consumers in industrialized countries, in particular in the US soon enough to slow or prevent the detrimental effects on the health of humans and the planet.

Parts of this post were taken from chapter 9, The One Health Concept of The Gut Immune Connection.

Emeran Mayer, MD is a Distinguished Research Professor in the Departments of Medicine, Physiology and Psychiatry at the David Geffen School of Medicine at UCLA, the Executive Director of the G. Oppenheimer Center for Neurobiology of Stress and Resilience and the Founding Director of the Goodman-Luskin Microbiome Center at UCLA.