A new study has found that people who eat a diet high in ultra-processed foods consistently have a specific elevated health marker that's a telltale sign of chronic inflammation – even without any obvious symptoms of illness. This inflammation is a slow burn, contributing to diseases including heart conditions, diabetes and even some cancers.
Florida Atlantic University (FAU) researchers analyzed data from 9,254 US adults in the National Health and Nutrition Examination Survey (NANES), which included information on diet, a range of health factors and blood analyses, focusing on one particular test for high-sensitivity C-reactive protein (hs-CRP). CRP is a protein produced by the liver in response to inflammation, but while spikes in CRP levels are generally from inflammation caused by infection of injury, hs-CRP readings are indicative of subtle, chronic inflammation.
The scientists assessed ultra-processed food (UPF) intake as a percentage of the total calories making up an individual's diet and then grouped these people into four categories based on intake – Group 1 had the lowest intake of UPFs, Group 4 the highest. They then looked at hs-CRP levels across all cohorts to see if there was any association with food and chronic inflammation markers.
On average, people were getting around 35% of their daily calories from UPFs. In Group 1, UPFs made up between 0% to 19% of daily intake, while in Group 4, the highest, 60% to 79% of calories came from UPFs. When the researchers adjusted for age, sex, smoking, physical activity and other health measures, they found a clear association with inflammation. Those in the highest intake group were 11% more likely to show elevated hs-CRP levels than those in the lowest group. Even moderate consumers were affected: People who got 40 to 59% of their calories from UPFs showed a 14% greater likelihood of hs-CRP elevated markers. The 20 to 39% group registered a smaller 7% increase, which wasn’t statistically significant.
What's more, the trend was especially pronounced in certain subgroups. Adults aged 50 to 59 years had a 26% higher risk of elevated inflammation compared to those in their late teens and 20s. Size was the most powerful driver, with obese participants facing an 80% higher risk than peers at a healthy weight. Current smokers also stood out, with a 17% higher risk than those who had never smoked. By contrast, physical inactivity didn’t appear to make a significant difference.
So, what does this mean? While not able to show direct causation, the researchers found a meaningful link between high hs-CRP readings and the amount of UPFs in an individual's diet – which was further impacted by age and obesity, both which made people more sensitive to inflammation already.
However, a 2022 study using Australia’s Melbourne Collaborative Cohort found that every extra 100 g of ultra-processed food consumed daily was associated with a 4% rise in hs-CRP – even after adjusting for BMI. That suggests inflammation isn’t just a byproduct of weight gain – it might also be a direct metabolic response to the substances used in processing.
While the percentages help us understand more about the relationship between inflammation and UPFs, the real importance lies in what they represent. Elevated hs-CRP points to a background "hum" of inflammation that quietly drives heart disease, diabetes and other chronic conditions. The results suggest it’s not just excess calories or fat we need to worry about, but the degree of food processing itself. These products generally have a reduced nutritional value, are made for an extended shelf life and tend to be less satisfying, which can lead to overconsumption.
“C-reactive protein is produced by the liver, and the hs-CRP protein test is a simple, affordable and highly sensitive measure of inflammation as well as a reliable predictor of future cardiovascular disease,” said Charles H. Hennekens, M.D., the senior academic advisor at FAU's Schmidt College of Medicine. “We believe that health care professionals may wish to consider actively engaging with their patients about the risks of UPFs and benefits of increasing whole food consumption.”
The hs-CRP test is widely used as a predictor of heart disease and stroke risk, because chronic low-grade inflammation contributes to plaque buildup in arteries (atherosclerosis). But, until now, there hasn't been much research linking UPF intake and hs-CRP levels that's representative of the US general population.
“These findings, based on a large and nationally representative sample of US adults, clearly show that people who consume the highest amounts of ultra-processed foods have significantly higher levels of high-sensitivity C-reactive protein, a key marker of inflammation,” said senior author Allison H. Ferris, M.D., the professor and chair of the FAU Department of Medicine. “These results carry important implications not only for clinical practice and public health strategies but also for future research aimed at understanding and reducing the health risks associated with ultra-processed food consumption.”
The authors also highlight how, in spite of a growing body of evidence that smoking was bad, it still took decades for health officials and policy makers to shift advice on tobacco use. They fear history may be repeating when it comes to UPFs. Researchers have already been sounding the alarm here for more than half a decade. A recent study also found that consumers, who are wanting to make better choices, are confused about what foods they should be avoiding.
“The multinational companies that produce ultra-processed foods are very influential, much like tobacco companies were in the past, so policy changes to promote whole foods and reduce UPF consumption may take time,” said Hennekens. “However, government efforts to reduce harmful additives, improve food labeling, and promote healthier options in programs and schools are important steps in the right direction. At the same time, health care providers should be aware of the challenges many people face in accessing affordable, healthier choices, which calls for a broader and coordinated public health response.”
The study was published in The American Journal of Medicine.
Source: Florida Atlantic University
