Findings could reduce the need for self-reporting in future nutritional studies and lead to new clinical laboratory testing
Clinical laboratory testing may one day influence whether a person snacks on a bag of chips every day or chooses to eat healthy foods instead.
Researchers at the National Institutes of Health (NIH) reported that they have identified biomarkers in blood and urine that can indicate an individual’s consumption of ultra-processed foods (UPF).
Scientists discovered a signature that is predictive of a dietary pattern that’s high in ultra-processed food, study leader Erikka Loftfield, PhD, MPH, epidemiologist and principal investigator with the NIH, told the Associated Press (AP).
Using data on the biomarkers—metabolites left after the body breaks down food—the researchers devised a “poly-metabolite score” that could potentially “reduce the reliance on, or complement the use of, self-reported dietary data in large population studies,” according to an NIH press release.
This will be helpful because, according to the AP, “Typical nutrition studies rely on recall: asking people what they ate during a certain period. But such reports are notoriously unreliable because people don’t remember everything they ate, or they record it inaccurately.”
“Limitations of self-reported diet are well known. Metabolomics provides an exciting opportunity to not only improve our methods for objectively measuring complex exposures like diet and intake of ultra-processed foods, but also to understand the mechanisms by which diet might be impacting health,” said Loftfield in the press release.
Thus, it’s conceivable that one day clinical laboratory testing could affect people’s food choices and help to improve their health.
The researchers published their study in the journal PLOS Medicine titled, “Identification and Validation of Poly-Metabolite Scores for Diets High in Ultra-Processed Food: An Observational Study and Post-Hoc Randomized Controlled Crossover-Feeding Trial.”
“There’s a need for both a more objective measure and potentially also a more accurate measure,” Erikka Loftfield, PhD, MPH, epidemiologist and principal investigator with the NIH, told the Associated Press. (Photo copyright: National Cancer Institute.)
Study Methodology
The findings were based in part on an earlier study of 718 AARP members, aged 50-74, who agreed to submit blood and urine samples. The participants also completed dietary recall reports.
“The researchers found hundreds of metabolites that correlated with the percentage of energy from ultra-processed foods in the diet,” the NIH press release noted. “Using machine learning, researchers identified metabolic patterns associated with high intake of ultra-processed foods and calculated poly-metabolite scores for blood and urine separately.”
To test their findings, the researchers referred to a 2019 NIH study involving 20 adults aged 18 to 50. Under carefully controlled conditions, these participants spent two weeks consuming high levels of ultra-processed foods, followed by two weeks consuming no ultra-processed foods. As with the AARP cohort, they also submitted blood and urine samples. The poly-metabolite score proved to be an accurate measure of which diets they had consumed, the researchers reported.
The researchers acknowledged limitations in the study that will necessitate further research. “Study participants were older US adults whose diets may vary from other populations,” the authors noted. “Poly-metabolite scores should be evaluated and iteratively improved in populations with diverse diets and a wide range of UPF intake.”
Ultra-Processed Foods Defined
The NIH defines ultra-processed foods as “ready-to-eat or ready-to-heat, industrially manufactured products, typically high in calories and low in essential nutrients.” Diets high in these foods have been associated with “increased risk of obesity and related chronic diseases, including some types of cancer,” the press release noted.
In identifying these foods, the researchers cited a 2019 paper published in the journal Public Health Nutrition (PHN). The paper relied on the NOVA classification system, which makes a distinction between “processed” and “ultra-processed” foods. The latter typically contain “food substances never or rarely used in kitchens,” or cosmetic additives “whose function is to make the final product palatable or more appealing,” the PHN paper noted.
“From sugary cereals at breakfast to frozen pizzas at dinner, plus in-between snacks of potato chips, sodas and ice cream, ultra-processed foods make up about 60% of the US diet,” the AP reported in an earlier story. “For kids and teens, it’s even higher—about two-thirds of what they eat.”
—Stephen Beale