As ultra-processed foods (UPFs) now make up more than half of daily calories for many Americans, scientists are seeking reliable biological markers to measure actual intake beyond self-reported dietary surveys.
A recent study published in PLOS Medicine by researchers from the U.S. and Brazil has identified specific metabolites in blood and urine that serve as objective indicators of UPF consumption.
Understanding Ultra-Processed Foods and Their Health Impact
Ultra-processed foods include packaged snacks, sugary beverages, and ready-to-eat meals made primarily from refined ingredients and additives. These foods are linked to increased risks of obesity, type 2 diabetes, heart disease, and certain cancers.
Traditional dietary surveys rely on memory and self-reporting, which can be inaccurate, while existing food classification systems like Nova require detailed data often unavailable in large studies.
The Study Design and Methods
The researchers analyzed data from the IDATA Study, involving 1,082 adults aged 50 to 74 years, mostly White, which may limit applicability to other groups.
Of these, 718 participants provided both dietary and biological data. Participants completed up to six web-based 24-hour dietary recalls over a year, with foods classified by the Nova system to calculate the percentage of energy from UPFs.
Blood and two types of urine samples (24-hour and first morning void) were collected at two time points six months apart. Using advanced mass spectrometry, the team identified over 1,000 metabolites, including lipids, amino acids, carbohydrates, and vitamins. Statistical analyses adjusted for age, sex, race, BMI, and smoking status to find metabolites correlated with UPF intake.
To validate their findings, researchers tested the metabolite patterns in a controlled feeding trial where 20 adults consumed diets with either 80% or 0% UPF for two weeks each. This helped confirm that the metabolite signatures could detect real-time dietary differences.
Key Findings
The study revealed hundreds of metabolites in blood and urine that correlate strongly with UPF intake. Notably:
191 blood metabolites and 293 urine metabolites showed significant associations.
Four metabolites were consistent markers in both blood and urine:
(S)C(S)S-S-methylcysteine sulfoxide, N2,N5-diacetylornithine, and pentoic acid (all negatively associated with UPF intake)
N6-carboxymethyllysine (positively associated), linked to harmful advanced glycation end-products related to diabetes and heart disease.
Higher UPF intake corresponded with lower levels of beneficial compounds like β-cryptoxanthin, a marker of fruit and vegetable consumption.
Metabolic pathways affected included xenobiotic metabolism (processing of foreign substances), amino acid, lipid, carbohydrate, and energy metabolism, indicating broad biological effects of UPFs.
The poly-metabolite scores developed showed moderate ability to distinguish UPF intake (AUCs between 0.66 and 0.78), performing well in both observational and controlled settings.
Practical Implications and Future Directions
This study marks a significant advance in objectively measuring UPF consumption using biological samples, which can improve nutrition research and public health monitoring. However, the findings are preliminary and need validation in more diverse and younger populations. The metabolite scores also require refinement to enhance accuracy and predictive power for long-term health outcomes.
For individuals, the research reinforces the importance of limiting ultra-processed foods and increasing whole food intake, such as fruits and vegetables, to maintain beneficial nutrient levels and avoid harmful compounds associated with processed diets.
Conclusion
Blood and urine metabolite profiling offers a promising, objective method to assess ultra-processed food intake, overcoming limitations of self-reported dietary data. As this tool evolves, it could help researchers better understand diet-related health risks and guide practical dietary recommendations for healthier living.
Suggestions for Healthy Living:
Prioritize whole, minimally processed foods like fresh fruits, vegetables, whole grains, and lean proteins.
Limit consumption of packaged snacks, sugary drinks, and ready-to-eat meals high in additives.
Use awareness of food processing levels to make informed dietary choices that support long-term health.
Support ongoing research by participating in nutrition studies or using validated dietary tracking tools.
By combining scientific insights with practical habits, individuals can reduce the hidden health risks posed by ultra-processed foods.
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