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<\/a>\u201cI don\u2019t have time to cook today, maybe I\u2019ll just have a quick bite\u2026\u201d Credit: Wikimedia Commons<\/p>\nUltra-Processed, Ubiquitous \u2014 and Unmeasured<\/p>\n
From sugary cereals and sodas to factory-made bread and frozen pizzas, ultra-processed foods now dominate diets across the globe. In the United States, they account for nearly 60% of the average person\u2019s calorie intake. These foods are engineered for shelf-life, flavor, and profit \u2014 often at the expense of nutrition.<\/p>\n
But scientists have struggled to measure just how much of these foods people actually consume. Most studies rely on food diaries or dietary recall \u2014 tools as unreliable as memory itself.<\/p>\n
\u201cThere\u2019s a need for both a more objective measure and potentially also a more accurate measure,\u201d Erikka Loftfield, an epidemiologist at the U.S. National Cancer Institute and lead author of the study, told The Associated Press<\/a>.<\/p>\n To address that gap, Loftfield and her colleagues turned to metabolites \u2014 molecules produced as our bodies digest and process food. These tiny chemical traces linger in our blood and urine, offering a molecular snapshot of what we\u2019ve been eating.<\/p>\n In a study involving 718 adults aged 50 to 74, researchers collected blood and urine samples from each participant twice over a year. Participants also provided detailed food logs. The scientists then used machine learning to analyze over 1,000 metabolites, searching for patterns that aligned with ultra-processed food consumption.<\/p>\n What they found was striking. People with higher UPF consumption \u2014 sometimes as much as 82% of their daily calories \u2014 had distinct metabolic signatures. Their samples contained more markers linked to type 2 diabetes and even traces of chemicals associated with food packaging. Conversely, they had fewer metabolites from fresh fruits and vegetables.<\/p>\n To test their method, the team drew on data from a tightly controlled study at the NIH Clinical Center, published in Cell Metabolism<\/a>. Twenty volunteers lived on-site and ate only what researchers gave them \u2014 two weeks of a diet rich in ultra-processed foods, followed by two weeks of whole foods, or vice versa.<\/p>\n The researchers could tell, with precision, when each participant switched diets \u2014 not by what they reported eating, but by what their blood and urine revealed.<\/p>\n \u201cWe found this signature that was sort of predictive of this dietary pattern that\u2019s high in ultraprocessed food and not just a specific food item here and there,\u201d Loftfield said.<\/p>\n From these results, the team created what they call a \u201cpoly-metabolite score.\u201d With just 28 blood markers or 33 urine markers, scientists could estimate how much energy someone derives from UPFs. <\/p>\n The Road Ahead<\/p>\n The study wasn\u2019t meant to prove that ultra-processed foods cause health problems. It also doesn\u2019t pinpoint which ingredients \u2014 emulsifiers, preservatives, artificial sweeteners \u2014 might be the true culprits.<\/p>\n Still, the ability to objectively measure UPF intake could help untangle these threads. With this tool, researchers could revisit old studies where biological samples were saved but diet was poorly documented. They could track long-term health outcomes \u2014 including cancer \u2014 with unprecedented accuracy.<\/p>\n If metabolite scoring is validated in larger, more diverse populations, it could usher in a new era of nutrition science \u2014 one that listens less to what people say they eat, and more to what their bodies reveal.<\/p>\n \u201cWe\u2019re sort of trapped in this industrial food-production system where we all eat ultra-processed food,\u201d Robinson told Nature<\/a>. \u201cIt\u2019s quite hard for most people to go back to fresh food, because our food systems are now set up like this.\u201d<\/p>\n And yet, thanks to a few drops of blood and urine, we may finally have a way to see what that diet is doing to us \u2014 molecule by molecule.<\/p>\n