Blood 'Remembers' Fast Food: Scientists Identify a Concerning Biological Signature

Scientists have identified, for the first time, a distinctive metabolic "fingerprint" in the blood of people who regularly consume large amounts of ultra-processed foods. The study, published in Critical Reviews in Food Science and Nutrition, helps explain why these foods have repeatedly been associated with an increased risk of cardiovascular disease, type 2 diabetes, obesity, certain cancers, and premature death.

The research was conducted by an international team led by scientists from the International Agency for Research on Cancer (IARC) of the World Health Organization (WHO). For the first time, the researchers applied targeted metabolomics to analyze such a large European cohort. This approach examines small molecules produced during metabolism, providing insight into how diet influences the body's biochemical processes.

The study included 15,200 participants from the large-scale European Prospective Investigation into Cancer and Nutrition (EPIC) project. The researchers conducted a detailed assessment of participants' diets, classifying foods according to the NOVA system, which categorizes foods into four groups based on their degree of processing, from minimally processed to ultra-processed.

The team then analyzed blood samples to measure the concentrations of a wide range of metabolites and fatty acids. Using statistical models, they examined the relationship between these biomarkers and participants' consumption of ultra-processed foods while adjusting for age, lifestyle, and other factors that could have influenced the results.

The analysis revealed that higher consumption of ultra-processed foods was associated with changes in the levels of 22 different metabolites. Individuals who consumed these foods more frequently had elevated concentrations of compounds considered markers of impaired fatty acid oxidation and mitochondrial dysfunction—an indication that the cells' energy-producing systems may be under metabolic stress.

At the same time, these participants showed lower levels of several important lipids that help maintain the stability and permeability of cell membranes and support normal communication between cells.

According to the authors, this pattern suggests that ultra-processed foods may disrupt normal lipid metabolism by stimulating the body's own lipid production while simultaneously impairing the natural breakdown and utilization of fats.

The study also identified alterations in eight plasma fatty acids. Higher intake of ultra-processed foods was associated with increased levels of stearic acid, a marker that may indicate either a high intake of saturated fats or underlying metabolic disturbances. Concentrations of several long-chain polyunsaturated fatty acids were also elevated.

According to the researchers, these findings indicate that the effects of ultra-processed foods extend beyond the fats they contain. Excessive consumption of rapidly absorbed carbohydrates may also stimulate the body's own lipid synthesis, leading to broader metabolic changes.

The authors conclude that the combination of reduced levels of protective fatty acids and increased signs of metabolic stress may represent one of the biological mechanisms through which ultra-processed foods increase the risk of chronic diseases. In other words, these foods may not only displace healthier dietary choices but also trigger unfavorable biochemical changes at the cellular level.