Molecules in blood and urine may reveal how much energy a person consumes from ultraprocessed foods, a key step to understanding the impact of the products that make up nearly 60% of the American diet, a new study finds.

It’s the first time that scientists have identified biological markers that can indicate higher or lower intake of the foods, which are linked to a host of health problems, said Erikka Loftfield, a National Cancer Institute researcher who led the study published Tuesday in the journal PLOS Medicine.

“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.