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Here’s the paradox: the most influential rules for the food we eat are the ones most of us ignore. But they are still important to millions of Americans.
The Dietary Guidelines for Americans, which are revised and issued by the federal government every five years, have a broad impact on what’s included in federal nutrition assistance programs, from WIC for women and young children to school lunches and meals for veterans or seniors. Yet, depending on the nutrient, 63% to 90% of people in the United States exceed recommended levels for added sugars, saturated fats and sodium; 75% falls under the standards for vegetables, fruit and dairy products.
Last week, an advisory panel made up of academic researchers met for two days of public discussion about what the next set of dietary guidelines should include. Their draft recommendations will go to the U.S. Department of Health and Human Services and the U.S. Department of Agriculture, with final guidance released late this year.
On Monday, the committee, or DGAC, said alcoholic beverages are not covered because a group within HHS and the National Academies of Sciences, Engineering and Medicine are already working on that issue. Ultra-processed foods are not part of the 2025-2030 guidelines proposals for another reason: the committee found too little high-quality evidence to support any guidance.
It may seem like two days of presentations have yielded few concrete changes after nearly two years of reviewing the scientific literature, so STAT asked three experts for their opinions.
How important are these recommendations?
Grace Chamberlin, policy officer, Center for Science in the Public Interest: The Dietary Guidelines are one of the biggest tools we have in this country to improve diets, health and the food system, so they are very important. I mean, the dietary guidelines have been called kind of the north star of the federal nutrition programs.
Marion Nestle, professor emeritus of nutrition and public health at New York University: In practice, no one pays much attention to it. Moreover, they never actually change. In 1980 they said: eat more vegetables and eat less food high in fat, sugar and salt. They still do that.
Will it just take a while for answers to things like ultra-processed foods?
Nesting: We now have two controlled clinical trials of ultra-processed foods that both show that people who eat diets based on these foods consume tons more calories than people who eat relatively unprocessed diets. What else do you need to know? The DGAC ignores these investigations because their duration was short.
When I was at the DGAC in 1995, we were charged with reviewing the science and doing our best to interpret its significance for nutritional advice for the American public. This assumed that the evidence would be difficult to interpret and incomplete. That changed with the 2005 guidelines. Since then, committees have been tasked with making evidence-based recommendations, and that’s all they’re doing. This is an impossible limitation, as the situation with ultra-processed foods shows.
JoAnn Manson, professor of medicine at Harvard Medical School and Brigham and Women’s Hospital: I think it’s important to have rigorous evidence before giving guidance on it. And I think one of them our findings was the diversity of ultra-processed foods: it was certainly not one size fits all. I suspect ultra-processed foods will be in the 2030 dietary guidelines. I think it will probably take a number of years before there is enough evidence, but I think it is moving in that direction.
Chamberlin: Overall, we agree with the DGAC’s draft conclusions on this issue. More research is needed to clarify what exactly causes the link between ultra-processed foods and weight gain or other health effects. And so I think this is certainly a research gap that needs to be addressed. Consumption of ultra-processed foods has been linked to an increased risk of cardiovascular disease, mortality and type 2 diabetes. But it is unclear which aspects of ultra-processed foods cause these health effects.
What can be done about limited evidence?
Nesting: Everyone underestimates how difficult nutritional research is. Just think about it. You can’t lock people up for decades to study what they eat under controlled conditions. You have to trust people to tell you what they are eating (everyone lies or, more politely, doesn’t remember). The studies are necessarily observational and cannot prove causality.
Chamberlin: As long as we rely on these clinical studies, it will be difficult to reach strong conclusions given the scientific rigor and standards to which the DGAC adheres to making recommendations based solely on the existing research. And current research lacks evidence on pregnancy and postpartum, children and adolescents and, crucially, many racial and ethnic subgroups. I think what they’re putting out in these public meetings, whether intentional or not, is a huge call to the research community to make sure that the next time we do this, there is research that is needed to build strong conclusions to be drawn.
What do you think the committee has added to the discussion?
Chamberlin: This Dietary Guidelines Advisory Committee has done a truly remarkable job integrating health equity into this process. To the best of their ability, they presented truly incredible progress in integrating more diverse research samples and protocols and conducting specific test food patterns. They are modeling food patterns of specific diets such as American Indian diets and Alaska Native diets.
Manson: I think the research on dietary patterns has been very useful. Identifying certain patterns that allow for flexibility, including some cultural influences and cultural differences, can really make a difference in not forcing people into these very restrictive types of recommendations. People really want to have room to play. They may understand that certain foods should be consumed less or less frequently, but they don’t want this to become a total taboo.
What is missing?
Chamberlin: [The committee is] limited by the existing research to ensure they have nationally representative data. There must be sufficient financial resources and time to collect diverse populations. That’s really important so that we can get more information about culturally inclusive diets and about actually breaking down all these different conclusions by race and ethnicity so that we can make sure that we don’t increase health disparities.
We are disappointed that the DGAC has not clarified or reaffirmed the quantitative limits for saturated fat and added sugars. And that’s not because of a lack of research or evidence-based basis. They failed to bring this up during the meeting. So we’re certainly interested in what their recommendations will be for quantitative limits on that.
STAT’s coverage of chronic health conditions is supported by a grant from Bloomberg Philanthropies. Us financial supporters are not involved in decisions about our journalism.