By Sarah Reinhardt

Back in February 2015, a committee of leading health and nutrition experts published a scientific report intended to inform the development of the 2015-2020 Dietary Guidelines for Americans (Dietary Guidelines), the national nutrition recommendations that guide the food choices of millions of kids, adults, seniors, and veterans every day. For the first time, the report contained a significant and rigorous review of research on sustainable eating, including the ways that our food choices can impact our climate, natural resources, and ability to produce food in the future.

But within months, sustainable diets were a nonstarter — at least as far as federal nutrition policy was concerned.

By October that year, the Obama administration's secretaries of agriculture and health and human services announced their decision to reject sustainable diets on principle. In doing so, they sided with meat industry groups who claimed it was outside the scope of the Dietary Guidelines, and who had lobbied Congress to help make sure it didn't happen.

Fast forward to today, as a new committee prepares the scientific report underpinning the 2020-2025 Dietary Guidelines—under an administration that has been decidedly less interested in science-based policymaking and protecting public health and the environment. It might seem all but impossible that sustainability should make a triumphant return now. Indeed, the 2020 committee wasn't asked to review current literature on the topic in the first place.

But a lot can change in five years.

From Congress to Corporate America, Climate Change is Catching Up These last five years, in particular, were the hottest ever recorded, producing some of the worst wildfires in history in places like California and Australia. Family farm bankruptcies hit an eight-year high as farmers across the U.S. faced extreme weather events, rising debt, and the fallout from a trade war. And new Congressional resolutions, corporate alliances, and youth-led movements helped catapult issues like conservation and climate change to the center of national conversation. Meanwhile, the evidence connecting dietary patterns, sustainability, and food insecurity has become a lot harder to ignore. Between July 2015 and September 2019, nearly 100 new scholarly articles were published on this topic, including 22 focused specifically on U.S. diets. That's more than four times the number of articles published on the same topic between 2000 and 2015 — in about a quarter of the time. How do I know?

Rethinking Dietary Guidance: A New Review of Sustainable Diets Research These are the findings of a new peer-reviewed paper I authored with colleagues at the Union of Concerned Scientists (UCS) and the Tufts University Friedman School of Nutrition Science and Policy which updated the systematic review of evidence on sustainable diets, replicating the methodology used by the scientific committee and USDA. In other words, it's the systematic review that could (and should) have been the charge of the 2020 committee. In addition to revealing a rapidly expanding body of research, our results pointed to several key conclusions: New US research continues to support prior findings that diets higher in plant-based foods and lower in animal-based foods can provide greater benefits for human health and the environment, and that such diets can be achieved without excluding any food groups. However, recent U.S. research challenges prior findings that diets aligning with national dietary guidelines are consistently more sustainable than what we're already eating. Our results show that the healthy diet recommended by the Dietary Guidelines may actually result in similar or increased heat-trapping emissions, energy use, and water use compared with the current average U.S. diet. What that means is this: if the Dietary Guidelines continue to sideline sustainability research, the diet the U.S. government recommends today could put a healthy diet further out of reach tomorrow. What's more, by sidelining conversations about sustainability, this committee of experts will miss out on a critical opportunity to identify research gaps that can help inform directions for future studies. Though we now know much more about the environmental impacts of our eating patterns, we still have a lot to learn about the social and economic dimensions of sustainable diets. For example, what are the costs associated with more environmentally sustainable diets? What would dietary shifts mean for farmers, food producers, and families — particularly those who face food insecurity and the consequences of climate change firsthand? The better we understand the practical implications of our diets, the better we can leverage that knowledge to protect our food systems and the health of our children, and their children, and so on, for generations to come.

What Do We Have to Lose? Although the 2020 committee wasn't charged with reviewing current research on dietary patterns and sustainability, it has an obligation to review current scientific and medical knowledge, as well as public comments, to ensure its findings address the most pressing diet-related threats to public health. What's more, the committee has an opportunity to include additional recommendations in a discussion section within its scientific report, due to federal agencies in May 2020. A lot can change in five years. We're not waiting until 2025 to find out what's at risk if we don't start supporting sustainable food policies. If you're an advocate, scientist, or other member of the general public, you can submit a public comment to the scientific committee through the UCS website until May 2020. (Check out our comment guide for tips and talking points.) If your organization or institution can lend its support to sustainable dietary guidance, join more than 50 organizations and leading public health experts nationwide in signing our letter to the U.S. Department of Agriculture and the Department of Health and Human Services asking them to include sustainability research in the 2020-2025 Dietary Guidelines. For more information, take a look at our policy brief, In Support of Sustainable Eating, and see the public comment I delivered to the Committee at a recent public meeting in Houston, below.