Hardly a day passes without a new study, and an ensuing round of headlines, sounding the alarm on ultraprocessed foods.
This wide-ranging category — including sodas, processed meats and many breakfast cereals, snack foods, frozen meals and flavored yogurts — has been linked to a range of health issues such as obesity, Type 2 diabetes, heart disease, gut conditions and depression.
So it may come as a surprise that when a committee of 20 of the country’s leading nutrition scientists met in late October to preview their recommendations for the next edition of the Dietary Guidelines for Americans, they said that there was not enough evidence to steer people away from the foods.
New limits on ultraprocessed foods, which make up a large share of what U.S. children and adults eat, could dramatically shift Americans’ diets, experts say. The dietary guidelines are used to set standards for federal food programs and inform how doctors counsel their patients about nutrition.
The U.S. Department of Agriculture and the Department of Health and Human Services will ultimately issue the guidelines, which are slated for release by the end of 2025. It’s unclear how Donald Trump’s return to the White House may affect them.
But the conclusions presented last month suggest such a policy could be unlikely.
Why didn’t the committee make a recommendation?
Part of the committee’s job was to review the research on ultraprocessed foods and then summarize those findings in a report they will submit to the federal agencies by December.
The expert committee was specifically tasked with evaluating whether ultraprocessed foods had any influence on body composition (like fat mass or waist circumference) or on the risk for obesity in children and adults.
In the 41 studies they reviewed — more than half of which were on children and adolescents — the experts found a relatively consistent link between ultraprocessed food consumption and a greater risk of becoming overweight or developing obesity.
But the committee cited a few serious concerns about the quality of the research, including that many studies were conducted outside of the United States, where ultraprocessed foods might be formulated differently.
Another issue was that many of the studies were based on diet records that were collected from participants decades ago, so the researchers conducting those studies had to make educated guesses about which foods were ultraprocessed and which were not.
Most of the studies included in the review were also observational, meaning they couldn’t prove cause and effect in the way that clinical trials can.
These concerns with the research led the committee to conclude that the evidence linking ultraprocessed foods to obesity was too limited to make a recommendation on them.
Instead, the committee focused their recommendations on those that had more robust research to back them, such as emphasizing diets centered on vegetables, fruits, legumes, whole grains, low-fat or non-fat dairy products, and fish or seafood. They did say that people should limit their consumption of processed meats and sugar-sweetened beverages — two products that are included in the ultraprocessed category, and have clear links to chronic disease.
Why are some experts frustrated with the committee’s conclusions?
Marion Nestle, a professor emerita of nutrition, food studies and public health at New York University, said that in her view, the committee set too high a bar for the studies they included in their review and left out important evidence on ultraprocessed foods.
They excluded the one randomized controlled trial from the United States that directly linked ultraprocessed food consumption with weight gain and overeating because of its small size and short duration — it included just 20 participants and lasted one month.
That was a mistake, Dr. Nestle said. That study was tightly controlled and clearly showed that ultraprocessed foods caused people to overeat and gain weight, she said. It’s difficult and expensive to conduct larger and longer-term trials in nutrition, she added, so rather than wait for more evidence, she thinks the existing research is sufficient to recommend that people eat fewer ultraprocessed foods.
Dr. Dariush Mozaffarian, a cardiologist and the director of the Food is Medicine Institute at Tufts University, agreed — adding that the evidence linking ultraprocessed foods to poor health is most consistent for those that are high in certain ingredients, like refined carbohydrates, added sugars and sodium.
If the next version of the dietary guidelines fails to include guidance on limiting ultraprocessed foods, it’s “a missed opportunity” to help steer Americans toward healthier diets, he added.
Because the dietary guidelines set nutrition standards for federal services, including by influencing what foods are available in schools and child care centers and through low income food programs like WIC, it’s also a missed opportunity for improving the health of the one in four Americans who are served by such programs, said Jerold Mande, an adjunct professor of nutrition at the Harvard School of Public Health and a former senior policy official at several federal food agencies.
“You’ve now left our kids with at least another decade of Lunchables as healthy foods in their school meals,” said Mr. Mande, who is also the chief executive of Nourish Science, a nonprofit focused on improving nutrition policy and research in the United States.
Why is there a disconnect?
It’s challenging for health experts to make recommendations on ultraprocessed foods when the science is still emerging, said Maya Vadiveloo, an associate professor of nutrition at the University of Rhode Island.
The ultraprocessed food category is broad, and if you recommend avoiding all of them, you might be cutting out some foods that are actually beneficial, she added. Breakfast cereals and yogurts, for instance, have been associated with lower risks of cardiovascular disease and Type 2 diabetes.
We need more research to tease out these nuances, several experts agreed. But some said that it’s not too soon to start incorporating some of this guidance into federal recommendations.
“Policymaking is always about having to make decisions with imperfect science,” Mr. Mande said. Just as the government took quick action on producing Covid vaccines while the science was still evolving, he said, it should respond with similar urgency to the high rates of chronic disease and obesity in the United States.
It doesn’t help, he added, that nutrition research is chronically underfunded in the United States. Just over 4 percent of the National Institutes of Health’s budget funds nutrition research, despite evidence that poor diets contribute to many chronic conditions. The dietary guidelines advisory committee “can’t really do their job, because they don’t have the research,” Mr. Mande said.
Dr. Mozaffarian empathized with the committee members, noting that they volunteer their time and expertise for two years and are often unfairly criticized for their work.
“Industry can do almost anything to food without proving it’s safe,” such as combining nutrients and flavors to make foods irresistible and incorporating additives with limited understanding of how they affect us, he said.
Yet the dietary guidelines advisory committee can only recommend that people avoid certain foods when there’s convincing evidence that they’re harmful, Dr. Mozaffarian said. “It’s just an unfair fight from the start.”
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