Last week in Houston, a federal advisory committee convened for the fourth time to deliberate the science that will shape the 2020-2025 Dietary Guidelines for Americans. Revised every five years to reflect current science, these guidelines are the nation’s leading set of evidence-based nutrition recommendations, and they influence the food choices made by millions of people every day.
As one would hope, the medical doctors, public health professionals, and nutrition scientists sitting around the table last week are experts in their fields. But they’re also people, and in addition to their respective expertise, they brought perspective, frustration, and even a little bit of humor to the table. After spending a day and a half listening and taking notes, I came out with five quotes that seemed to define the discussion at the fourth meeting of the 2020 Dietary Guidelines Advisory Committee.
“Burgers and sandwiches.”
Dr. Regan Bailey was the first to bring up burgers and sandwiches, but the phrase was repeated often (sometimes in unison) thereafter. The subcommittee chaired by Dr. Bailey, charged with evaluating current dietary patterns, found that a substantial amount of the protein, grains, dairy, and even vegetables in the average US diet is eaten in the form of burgers and sandwiches.
These data points speak to our culture as much as our diet quality, but they probably help explain why US adults only consume about half as many fruits and vegetables as we should.
Dr. Joan Sabaté took the news with a healthy dose of optimism, pointing out that our predictable preferences may present an opportunity to leverage these foods to improve both health and other social values, including environmental sustainability—demonstrated, for example, by the recent surge of interest in plant-based burgers and other meat substitutes. (Though there’s no guarantee that current plant-based products will accomplish either aim.)
“It’s so disheartening.”
These words uttered by Dr. Rick Mattes were (somehow) not in reference to the state of our diets, but instead to the state of available science. Specifically, Dr. Mattes was lamenting the low number of studies available to answer many of the committee’s research questions. A lack of high-quality, relevant research was a persistent theme throughout the meeting, as the committee determined that there was insufficient evidence to draw conclusions on a number of topics.
Why?
One explanation is that the Dietary Guidelines use a rigorous process for screening studies to decide if their methods and results are reliable and relevant to the US population. That means that a lot of studies get filtered out along the way.
But, maybe more importantly, there also just isn’t enough public funding for nutrition research. As reported by Politico last year, two of the leading federal agencies funding nutrition research—the National Institutes of Health and the Agricultural Research Service—dedicated less than 5 percent and just over 7 percent of their budgets, respectively, to human nutrition.
“We hope no one ever does a randomized controlled trial where the endpoint is death.”
We owe this science joke to Dr. Carol Boushey, chair of the subcommittee examining the relationship between our overall diets and rates of disease and death. She’s referring to the fact that the subcommittee’s review relied on observational studies—nonexperimental studies that require watching or tracking groups of people over time—as opposed to randomized controlled trials, which are experiments that assign certain treatments to different groups. While randomized controlled trials are the gold standard in clinical research, they’re often impractical in long-term nutrition studies, as it is generally considered unethical to enroll people in a trial to test which diet will kill them more quickly (hence the joke).
But this offhanded remark sheds light on a controversy in nutrition science that came to a head in recent months. Late last year, a series of articles published in the Annals of Nutrition refuted current recommendations on red and processed meat, declaring that advice to limit these foods is based on low-quality evidence (read: observational studies).
While the study authors were swiftly and sharply criticized for their conclusions, as well as the lead author’s failure to report a key conflict of interest, it was clear that their critique of current research methods struck a nerve.
“All carbohydrates are not equal.”
If you only attended the second day of the meeting, during which various representatives of various advocacy groups and members of the general public provided oral comments to the committee, you might think the low-carb diet is being grossly neglected in current dietary guidance. That’s because eight out of 51 commenters expressed support for the low-carb diet in their comments. (Called it.)
And while stakeholders like the Low-Carb Action Network and Low Carb USA are clearly excellent organizers, their case remains unsubstantiated by science.
In its review of low-carb diets, Dr. Boushey’s subcommittee found that there was very little evidence supporting their effectiveness, and furthermore suggested that the quality of nutrients in the diet is more important than the quantity. Or, as Dr. Jamy Ard put it, “All carbohydrates are not equal.”
“We need to address the inequitable access to healthy diets in the US.”
Dr. Kay Dewey’s remark was made in response to another committee member who commented that we live in a country where we spend a relatively low percent of our income on diets.
Though seemingly incongruous, both statements are true.
There are vast disparities in healthy food access in communities across the US, particularly when it comes to low-income populations and people of color, who generally have fewer supermarkets and more convenience stores and fast-food restaurants in their neighborhoods.
And, broadly speaking, the US does spend relatively less on food than other countries. In 2015, US households spent an average of 12.5% of their total income on food, about half of which is eaten at home. This level of spending is among the lowest in the world.
But improving access to healthy diets won’t be achieved by building more grocery stores, and it certainly won’t be achieved by making food cheaper, which would only put greater strain on a labor force that already sees some of the lowest wages and poorest working conditions of any US industry. Addressing the underlying drivers of diet-related health disparities, including a history of state-sanctioned policies designed to perpetuate social and economic inequities, will require more complex and multifaceted solutions.
Will the Dietary Guidelines be able to deliver these kinds of solutions? Probably not—or at least not yet.
Will the committee continue to recognize the critical context behind dietary choices and diet-related health disparities? Let’s help make sure they do.
The fifth and final meeting of the committee will take place March 12-13, and the committee will accept written public comments through May 2020. For more information on submitting a public comment, including helpful tips and talking points, check out our Dietary Guidelines comment guide.