Study details
The serial cross-sectional analysis used 24-hour dietary recall data from a nationally representative sample from 10 NHANES cycles for the range of 1999-2000 to 2017-2018. The weighted mean age of the cohort was 10.7 years and 49.1% were girls.
Among the subgroups of ultraprocessed foods, the estimated percentage of energy from ready-to-heat and ready-to-eat mixed dishes increased from 2.2% to 11.2% (difference 8.9%; 95%, CI, 7.7-10.2).
Energy from sweets and sweet snacks increased from 10.7% to 12.9% (difference 2.3%; 95% CI, 1.0-3.6), but the estimated percentage of energy decreased for sugar-sweetened beverages from 10.8% to 5.3% (difference −5.5%; 95% CI, −6.5 to −4.5).
In other categories, estimated energy intake from processed fats and oils, condiments, and sauces fell from 7.1% to 4.0% (difference −3.1%; 95% CI, −3.7 to −2.6, all P < .05 for trend).
Not surprisingly, ultraprocessed foods had an overall poorer nutrient profile than that of nonultraprocessed, although they often contained less saturated fat, and they also contained more carbohydrates, mostly from low-quality sources with added sugars and low levels of dietary fiber and protein.
And despite a higher total folate content in ultraprocessed foods because of fortification, higher-level consumers took in less total folate owing to their lower consumption of whole foods.
The authors cautioned that in addition to poor nutrient profiles, processing itself may harm health by changing the physical structure and chemical composition of food, which could lead to elevated glycemic response and reduced satiety. Furthermore, recent research has linked food additives such as emulsifiers, stabilizers, and artificial sweeteners to adverse metabolomic effects and obesity risk. Pointing to the recent success of efforts to reduce consumption of sugary beverages, Dr. Zhang said, “We need to mobilize the same energy and level of commitment when it comes to other unhealthy ultraprocessed foods such as cakes, cookies, doughnuts, and brownies.”
The trends identified by the Tufts study “are concerning and potentially have major public health significance,” according to an accompanying JAMA editorial.
“Better dietary assessment methods are needed to document trends and understand the unique role of ultraprocessed foods to inform future evidence-based policy and dietary recommendations,” wrote Katie A. Meyer, ScD, and Lindsey Smith Taillie, PhD, of the Gillings School of Global Public Health at the University of North Carolina in Chapel Hill.
The editorialists share the authors’ view that “a conceptual advancement would be to consider the level and characteristics of processing as just one of multiple dimensions (including nutrients and food groups) used to classify foods as healthy or unhealthy.” They pointed out that the Pan American Health Organization already recommends targeting products that are ultraprocessed and high in concerning add-in nutrients.
They cautioned, however, that the classification of ultraprocessed foods will not be easy because it requires data on a full list of ingredients, and the effects of processing generally cannot be separated from the composite nutrients of ultraprocessed foods.
This presents a challenge for national food consumption research “given that most large epidemiological studies rely on food frequency questionnaires that lack the information necessary to classify processing levels,” they wrote.
This study was supported by the National Institutes of Health and the São Paulo Research Foundation. Coauthor Dariush Mozaffarian, MD, a cardiologist at Tufts University, disclosed support from the Bill & Melinda Gates Foundation, the National Institutes of Health, and the Rockefeller Foundation as well as personal fees from several commercial companies. He has served on several scientific advisory boards and received royalties from UpToDate, all outside of the submitted work. Dr. Meyer reported a grant from choline manufacturer Balchem. Dr. Taillie reported funding from Bloomberg Philanthropies. Dr. Zhang had no disclosures. Dr. Katzow disclosed no competing interests.