Molecules found in the blood and urine may offer a groundbreaking new way to measure just how much ultraprocessed food people consume, an advance that could reshape the way scientists study the link between diet and health, according to a new study published Tuesday in PLOS Medicine.

The research, led by Erikka Loftfield of the National Cancer Institute, is the first to identify specific biological markers in blood and urine that correlate with higher or lower intake of ultraprocessed foods, items that make up nearly 60% of the average American diet.

“It can potentially give us some clues as to what the underlying biology might be between an ultraprocessed food association and a health outcome,” Loftfield said.

Ultraprocessed foods (UPFs), such as sugary cereals, sodas, chips, frozen pizzas, and snack bars, are manufactured products often made with additives, preservatives, and artificial ingredients rarely found in home kitchens. Although these foods are omnipresent in the U.S. and other countries, studying their long-term health effects has proven difficult because accurately recording food intake remains a major challenge.

The limits of self-reporting

Traditionally, dietary studies rely on people recalling what they’ve eaten—an approach that is widely recognized as flawed.

“There’s a need for both a more objective measure and potentially also a more accurate measure,” Loftfield explained.

To build a more reliable method, Loftfield and her team analyzed data from over 1,000 older U.S. adults enrolled in an existing study of AARP members. More than 700 of those participants provided blood and urine samples along with detailed dietary recall data collected over a year.

Researchers identified hundreds of metabolites—byproducts of digestion and other bodily processes—that were linked to the amount of energy participants consumed from UPFs. From that analysis, they created a scoring system consisting of 28 blood markers and up to 33 urine markers that could reliably indicate the level of UPF consumption.

“We found this signature that was sort of predictive of this dietary pattern that’s high in ultraprocessed food and not just a specific food item here and there,” Loftfield said.

Some of the most consistent biomarkers included two amino acids and a carbohydrate that appeared in at least 60 of 100 test iterations. One marker even showed a possible connection between UPF-heavy diets and an increased risk of type 2 diabetes.

Valid at the individual level

To test the accuracy of the tool, Loftfield applied it to data from a rigorously controlled 2019 National Institutes of Health (NIH) study in which 20 adult participants lived in a research facility for a month. Each person was given alternating two-week diets of ultraprocessed and unprocessed foods matched for calories, sugar, fat, fiber, and macronutrients, and allowed to eat as much as they wanted.

Loftfield’s team was able to distinguish when participants were consuming large amounts of UPFs based solely on their metabolite scores.

“The results suggested the markers were ‘valid at the individual level,’” Loftfield noted.

A promising future for nutrition science

Experts unaffiliated with the study have hailed the findings as a potential turning point in nutritional science.

“With more research, these metabolic signatures can begin to untangle the biologic pathways and harms of UPF and also differences in health effects of specific UPF food groups, processing methods and additives,” said Dr. Dariush Mozaffarian, director of the Food Is Medicine Institute at Tufts University.

Loftfield hopes the metabolite tool can be used in existing population studies where blood and urine samples are already collected, especially to explore links between UPF intake and diseases like cancer.

However, she also voiced concerns about declining funding for government-backed scientific research.

“There’s a lot of interest across the board—scientifically, public interest, political interest, in the question of: Does ultraprocessed food impact health and, if so, how?” Loftfield said. “How can we fund the studies that need to be done to answer these questions in a timely way?”

As ultraprocessed foods continue to dominate global diets, these findings could be the first step toward providing the scientific evidence necessary for public health policy and personal dietary choices grounded in biological precision.