2 Hot Dogs or 1 Large Cookie? A Study of Risks by Amount of Ultraprocessed Food

A line could be drawn between how much ultraprocessed food a person eats and their risk of major chronic diseases, according to a meta-analysis.

Covering 51 prospective cohort studies and over 8.8 million participants, there were clear dose-dependent links between ultraprocessed food consumption and bad health outcomes. Each 100 g of these foods eaten daily was associated with significantly higher risks of:

• Cardiovascular events (HR 1.14, 95% CI 1.06-1.22)
• Cancer (HR 1.04, 95% CI 1.02-1.06)
• All-cause mortality (HR 1.03, 95% CI 1.02-1.05)
• Metabolic syndrome (MetS)/diabetes (HR 1.02, 95% CI 1.01-1.04)

That 100 g can represent a large store-bought cookie, about four servings of potato chips, or roughly two hot dogs.

“Consuming UPFs [ultraprocessed foods] was associated with higher risks of multiple chronic diseases and all-cause mortality with low or moderate evidence. Reducing dietary intake of UPFs may therefore be relevant for chronic disease prevention,” concluded the group led by Xiao Liu, MD, PhD, of Duke-NUS Medical School in Singapore, and Sun Yat-Sen Memorial Hospital, Sun Yat-sen University in Guangzhou, China, in Family Medicine and Community Health.

Liu’s group urged clinical action, especially in primary care.

“[P]rimary care practitioners may advise gradual reduction of UPFs intake towards approximately 10%-20% of total daily energy intake, while considering which UPF subtypes are most strongly associated with adverse outcomes. Replacing UPFs with minimally processed alternatives, rather than restriction alone, may provide a more sustainable and patient-centered approach,” the authors suggested.

There is no formal definition of ultraprocessed food, but it is commonly accepted to indicate products that undergo extensive industrial processing and contain multiple additives. These foods tend to have lower nutritional value and high energy, which delays the feeling of fullness and may increase eating rate and overall food intake. By one estimate, ultraprocessed foods account for more than half the calories consumed in the U.S. diet.

With HHS Secretary Robert F. Kennedy Jr. prioritizing nutrition in his “Make America Healthy Again” agenda, the FDA recently said it completed work on the federal government’s first-ever definition of ultraprocessed food; it has reportedly submitted the definition to the White House for further review.

While there are plenty of studies indicating that diets high in ultraprocessed foods are associated with health harms, the idea that these foods directly cause chronic illness is unproven, however.

The lack of rigorous supporting randomized trials was emphasized by statistician Adam Jacobs, PhD, MSc, from Ergomed in Guildford, England, in comments posted to the Science Media Centre (SMC) website.

“People who consume low amounts of UPF are generally more affluent than those who consume more UPF, and we know that poverty is one of the strongest predictors of poor health. So it is possible that UPF consumption is simply a marker for poverty, rather than being harmful per se,” according to Jacobs. “There are other possible confounding variables to consider, to do with lifestyle. For example, people doing shift work or with particularly stressful lives may eat more UPF. Few studies adjusted for such factors.”

There are also major issues with observational studies trying to measure food intake. Consumption of ultraprocessed foods had been assessed by food frequency questionnaires, 24-hour recalls, or dietary history in studies included in the meta-analysis. Liu and colleagues acknowledged that dietary self-reporting may be a source of potential exposure misclassification and measurement error.

“Measuring food intake is notoriously difficult, as people are often not very good at remembering what they ate,” agreed Gunter Kuhnle, PhD, of the University of Reading in England, in a separate SMC entry. “Estimating UPF intake from these data is even more difficult for several reasons,” he continued, citing an ambiguous definition of ultraprocessed food and unclear food categories.

“Randomized controlled trials provide a much more nuanced picture — some trials show that adherence to dietary recommendations is more important than whether food is processed or ultraprocessed. It is therefore important to encourage the general public to follow current dietary recommendations, but there is little evidence that avoiding UPF is beneficial to health,” Kuhnle stressed.

The meta-analysis covered studies with participant ages ranging from 23.9 to 77 years on average; 46.4% were men.

Consumption of UPFs was significantly associated with cardiovascular events, cancer, obesity/overweight, MetS/diabetes, depression/anxiety, digestive diseases, and all-cause mortality.

However, the evidence was deemed low-certainty for all of these except the obesity/overweight endpoint, for which the evidence was considered only moderate-certainty.

“Future studies should adopt harmonized and subtype-specific UPF exposure metrics, improve dietary assessment methods, and clarify clinically meaningful intake thresholds across diverse populations,” Liu and colleagues urged.