- There is increasing evidence that ultra-processed foods (UPFs) are harmful to health, but the mechanisms by which they do so are not entirely clear.
- Now, a study has found that people with a high UPF intake have different blood metabolites, with higher levels of ‘bad’ fatty acids and fewer beneficial fatty acids, than those with a lower intake of these foods.
- The research also suggests that UPF consumption may stimulate the production of cholesterol and inhibit healthy lipid processing.
Ultra-processed foods (UPFs) are highly processed foods that contain additives. They generally contain high levels of fat, sugar, carbohydrates, sodium, and energy.
There is increasing evidence that they may be harmful to our health. One recent study linked UPF intake to 32 adverse health effects, including cardiovascular disease, type 2 diabetes, and obesity.
But how do UPFs have these adverse effects? A new study suggests that high UPF intake can alter metabolites in the blood, increasing levels of harmful fatty acids and decreasing levels of fats that are essential for cellular functions.
The study, published in Critical Reviews in Food Science and Nutrition, suggests that not only does excess fat from UPFs enter the blood, but that the foods may also stimulate the body to produce lipids from excess carbohydrates in the diet.
Jessica Blanco-López, MD PhD, lead author of the study, and Head of the Research Department at the School of Medicine, Universidad Francisco Marroquín, Guatemala, told Medical News Today:
“Our study adds biological evidence to the growing body of research linking ultra-processed food consumption with poorer health outcomes. Rather than focusing directly on disease, we identified a distinct metabolic signature associated with higher UPF intake. […] This helps us better understand the biological pathways through which UPFs may influence health.”
The researchers analysed data from the EPIC cohort study, in which more than 520,000 volunteers from 10 European countries — Denmark, France, Germany, Greece, Italy, the Netherlands, Norway, Spain, Sweden, and the United Kingdom — were enrolled between 1992 and 2000.
Most participants were aged between 35 and 70 years, with women making up around two-thirds of the cohort.
At enrolment into the EPIC study, all participants completed two comprehensive questionnaires, about lifestyle and about their diet during the previous 12 months, with a random sample of people completing a 24-hour dietary recall. They also gave blood samples and body measurements.
For this latest study, researchers analysed the dietary questionnaires of over 15,200 people. They categorised foods by the NOVA system, which groups foods into one of four groups according to how much processing they have undergone:
- NOVA 1 is unprocessed or minimally processed foods, such as fresh, dry or frozen fruit, vegetables, legumes, meat, fish, eggs and milk
- NOVA 2 are processed culinary ingredients — these include oils, butters, sugar, salt, and foods that have been pressed, refined, ground, milled or dried for use in cooking
- NOVA 3 includes processed foods, such as canned vegetables and fish, fruits in syrup, cheeses and freshly made breads, that are made by adding salt, oil, sugar to unprocessed or minimally processed foods
- NOVA 4 is UPFs, which are made from the products of industrial processes; containing flavors, colors and emulsifiers to increase palatability, they include soft drinks, sweet and savoury packaged snacks, reconstituted meat products and pre-prepared frozen foods.
The researchers recorded UPF intake in grams per day, rather than calories, to allow for consumption of low calorie or calorie-free foods and drinks that may contribute significantly to overall intake but not calorie intake.
Participants’ median intake of UPFs was around 12.6% of their diet. Actual UPF intake ranged from 0 to 2,890 grams (g) per day.
Thomas M. Holland, physician-scientist and assistant professor at the RUSH Institute for Healthy Aging, RUSH University, College of Health Sciences, Chicago, who was not involved in this study, commented to MNT that:
“This study adds another important layer to the growing body of evidence linking higher consumption of UPFs with poorer health. Rather than simply showing that people who consume more ultra-processed foods tend to have higher rates of chronic disease, the researchers identified metabolic signatures associated with higher UPF intake that may help explain why these associations exist. In other words, they identified measurable biological changes that accompany greater ultra-processed food consumption.”
People with higher UPF consumption had more of certain lipid derivatives that are biomarkers of impaired fatty acid oxidation and mitochondrial dysfunction, and less of several other lipids that are essential for cell membrane stability, permeability and cell signalling.
Blanco-Lopez told us that this “alteration in circulating fatty acids, particularly the lower levels of beneficial omega-3 fatty acids, such as DHA, together with higher levels of omega-6 fatty acids and industrial trans fats,” was one of the most important findings.
“We also observed changes in metabolites involved in lipid metabolism and energy metabolism,” she added. “Together, these findings suggest that higher consumption of ultra-processed foods is associated with a metabolic profile that may reflect disrupted lipid homeostasis.”
Holland outlined why these changes could be important for health, noting that “one of the more notable findings was that individuals consuming more ultra-processed foods tended to have higher circulating levels of industrial trans fats and certain saturated fatty acids, while having lower levels of beneficial omega-3 fatty acids, such as DHA.“
“These differences matter because the types of fats circulating in our blood can influence processes involved in cardiovascular, metabolic, and brain health,” he told us.
Blanco-Lopez concluded that their findings suggest that “what we eat leaves measurable fingerprints in our metabolism, and ultra-processed foods appear to leave a distinct one.”
These were observational findings, so cannot show a causative link between UPF consumption and poorer health outcomes. However, they add to evidence of the adverse effects of high UPF intake, and may help to explain the biological mechanism.
“Several of the metabolites and fatty acids identified in our study have previously been associated with conditions such as type 2 diabetes, cardiovascular disease, and obesity. While our study cannot establish that these metabolic changes cause disease, they may represent early biological changes that help explain why higher consumption of ultra-processed foods has consistently been linked to poorer long-term health outcomes in epidemiological studies.”
– Jessica Blanco-Lopez, MD PhD
Blanco-Lopez added that their findings should be replicated in other populations with different dietary habits, and that longitudinal studies and controlled feeding trials would help to clarify whether the findings derived from UPF consumption and contributed to development of chronic diseases.
Holland concurred, adding that “future research should include more contemporary cohorts, untargeted metabolomic approaches, and intervention studies that examine whether reducing ultra-processed food intake leads to improvements in these metabolic signatures over time.”
“Ultimately, healthy aging is built on consistent daily habits rather than perfection,“ he told us. “A dietary pattern centered on minimally processed foods, combined with regular physical activity, adequate sleep, stress management, avoiding tobacco, and maintaining meaningful social engagement, provides a strong foundation for preserving both physical function and cognitive health over the lifespan.“
“This study adds to the growing evidence that reducing reliance on ultra-processed foods may be one component of that broader healthy lifestyle,” he concluded.
