Scientists have identified molecules in blood and urine that can objectively reveal how much ultraprocessed food (UPF) a person consumes, according to a new study published in the journal PLOS Medicine.

The discovery is the first time scientists have found biological markers that represent higher or lower consumption of such foods, which now make up more than half 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," said Erikka Loftfield, a National Cancer Institute researcher who led the study.

Traditionally, nutrition studies have relied on self-reported food diaries or recall surveys, which are often plagued by inaccuracies and memory lapses.

"There's a need for both a more objective measure and potentially also a more accurate measure," Loftfield said.

Using advanced mass spectrometry, scientists measured over 1,000 metabolites in the samples and compared them to the percentage of daily energy participants consumed from UPFs.

Dr. Dariush Mozaffarian, director of the Food Is Medicine Institute at Tufts University, who was not involved in the study, called the findings "a major scientific advance."

Loftfield said she hopes that these new tools could be applied to existing studies with stored blood and urine samples to investigate links between UPF consumption and diseases like cancer.

One issue for such research is funding, despite the need and want for such 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?" she said. "How can we fund the studies that need to be done to answer these questions in a timely way?"