Are ultra-processed foods a public health hazard?

Yes, a growing and increasingly authoritative body of scientific evidence indicates that ultra-processed foods (UPFs) represent a genuine public health hazard, though some scientists urge nuance about how the category is defined and used.

What counts as a UPF

Ultra-processed foods are defined by the NOVA classification system as manufactured items containing minimal whole foods, alongside numerous substances that are of little or no culinary use (e.g. high-fructose corn syrup and modified starches) which are added to enhance the flavour, texture, and/or the shelf-life of the product. Examples include sugary sodas, packaged snacks, and frozen meals, and in many countries they now account for roughly half of caloric intake, especially among children.

The scale and strength of evidence

The most significant recent development is a major Lancet Series published in November 2025. The rise of ultra-processed foods in human diets is damaging public health, fuelling chronic diseases worldwide, and deepening health inequalities, according to a new Lancet Series on UPFs and human health. As NPR summarized the findings, there are three papers, published in The Lancet, reviewing years' worth of evidence—more than a hundred studies linking ultraprocessed foods to poor health outcomes, including increased risk of Type 2 diabetes, obesity, chronic kidney and heart disease, and even depression.

This builds on earlier systematic work. A widely cited 2024 umbrella review in BMJ examined 45 analyses published in the prior three years, involving about 10 million people in total, and found the most convincing or highly suggestive evidence linked diets rich in ultra-processed foods with increased risks for premature death, cardiovascular disease, mental health disorders, diabetes, obesity, and sleep problems, while associations with asthma, gastrointestinal disease, and some cancers were limited and need further investigation.

A more recent umbrella review found even broader associations: a higher risk of all-cause mortality, type 2 diabetes mellitus, mental and sleep disorders, cardiovascular, cerebrovascular, and digestive diseases, as well as all types of cancer in both sexes was found for adults, including colorectal and prostate cancer in men, and breast cancer in women. Overall, that review identified a significant association with an increased risk of at least 44 different human health effects, and newer studies continue to add conditions such as chronic kidney disease and chronic obstructive pulmonary disease to the list.

Quantifying the impact

The scale of the harm is striking in population terms. One 2025 global analysis found that each 10% increase in ultra-processed food intake increases the risk of early death (between ages 30–69) by 3%, in a dose-response relationship, and estimated that potentially 124,000 Americans die prematurely every two years due to ultra-processed food consumption.

Moving from correlation to causation

Importantly, 2025 brought experimental evidence beyond observational associations. A 2025 randomized controlled trial showed harmful effects of UPFs on weight gain and metabolic and reproductive health, regardless of excessive caloric intake—suggesting something about UPFs themselves, not just calories, drives harm. Researchers are now probing specific mechanisms: in an experimental study on mice, two widely consumed food additive emulsifiers caused transgenerational microbiota alteration that led to increased long-term susceptibility to metabolic and inflammatory diseases, and a large prospective cohort study revealed positive associations between exposure to two widely consumed food additive mixtures and higher type 2 diabetes incidence—notable because safety assessments of additives have typically been done substance by substance, even though mixtures are consumed daily by billions of people.

Cardiology researchers summarize plausible mechanisms as dysregulation of blood lipid profiles, alterations in gut microbiota composition, promotion of obesity, induction of systemic inflammation, exacerbation of oxidative stress and impairment of insulin sensitivity.

Vulnerable populations

Children appear particularly exposed and at risk. One analysis noted UPFs are contributing to 67% of the energy consumption of U.S. children in 2025, putting them at risk for insulin resistance and metabolic dysfunction-associated steatotic liver disease (MASLD), mental health concerns, and gut microbiome disruption.

Important caveats and scientific debate

Not every scientist agrees the picture is settled. In the same NPR report, researcher David Ludwig cautioned that by focusing on such an imprecise target as ultraprocessed foods, there's a risk of demonizing an overly broad category that includes both clearly harmful products and some minimally harmful ones. A 2025 Nature Reviews Endocrinology piece likewise notes that multiple factors are suspected to explain detrimental effects of UPFs, beyond their nutritional profile, including food additives—implying the "ultra-processed" label itself may be a crude proxy for several distinct harmful mechanisms rather than a single unified cause.

Additionally, not all UPFs behave identically: a late-2025 study found that high-quality, minimally processed plant foods significantly reduce cardiovascular risk, but when those plant foods are ultra-processed, the benefit changes—highlighting that processing level alone doesn't fully capture nutritional risk.

Some specific additive concerns also remain contested across regulators: the FDA withdrew approval for a synthetic dye based on potential carcinogenicity in murine models through mechanisms not relevant to humans and with no evidence from human studies, while the same additive is still approved for use by European and UK regulators—illustrating genuine scientific disagreement about which specific mechanisms are most human-relevant.

Bottom line

The 2025 Lancet Series, combined with mechanistic trials and large-scale cohort data, has shifted the scientific consensus toward treating UPFs as a serious public health concern worthy of policy intervention, driving rising disease rates and demand for urgent, worldwide policy action. At the same time, researchers continue to debate exactly which components of "ultra-processing" (additives, texture changes, nutrient dilution, or something else) are responsible, meaning the public health hazard is real and significant, but the precise causal pathways are still being refined.