Are ultra-processed foods a public health hazard?

Are Ultra-Processed Foods a Public Health Hazard?

The scientific consensus is increasingly leaning toward yes — a growing and substantial body of evidence links ultra-processed food (UPF) consumption to numerous adverse health outcomes, though the debate about mechanisms, causation, and the classification system itself is still active.

The Evidence for Harm

Scale of the problem: The U.S. is among the biggest consumers of UPF in the world, and UPF currently make up more than half of what U.S. adults eat on a daily basis, and two-thirds of what kids and teens eat. Some researchers put the figure even higher—up to 70% of the U.S. diet is composed of foods that are ultra-processed.

Major scientific statement: In late 2025, more than 40 prominent health experts published a series of papers in The Lancet concluding that UPF are a leading contributor to chronic disease. As one of the lead authors put it bluntly: "We can say now that truly ultraprocessed food represents a clear global threat to our health."

Associated health conditions: Across dozens of large cohort studies and meta-analyses, ultra-processed diets are linked to chronic health conditions like increased risk of becoming overweight and obesity, type 2 diabetes, high blood pressure, heart disease, chronic kidney disease and overall higher death rates. A 2024 umbrella review in the BMJ looked at 45 studies involving almost 10 million participants and suggested eating more ultraprocessed foods is linked to a higher risk of dying from any cause and has ties to 32 health conditions, including heart disease, mental health disorders, and type 2 diabetes.

A separate systematic review found 41 prospective cohort studies involving a total of 8,286,940 adult patients found ultra-processed food consumption was associated with hypertension, cardiovascular events, cancer, digestive diseases and all-cause mortality. Dose-response data from that review showed each additional 100 grams a day was linked to a 14% higher heart risk and an 11% higher blood pressure risk.

Moving beyond association toward causation: 2025 was described as a turning point, as experimental, clinical and epidemiological studies converged to elucidate the underlying mechanisms at play. Notably, a 2025 randomized controlled trial showed harmful effects of UPFs on weight gain and metabolic and reproductive health, regardless of excessive caloric intake. Animal studies have also found plausible biological mechanisms — food additive emulsifiers caused transgenerational microbiota alteration that led to increased long-term susceptibility to metabolic and inflammatory diseases in mice.

Equity concerns: UPF are frequently more affordable than less-processed foods or fresh produce, and their low cost and wide availability may drive health disparities among populations who already face hunger, undernutrition and higher rates of chronic disease.

The Scientific Debate and Limitations

Despite this evidence, the issue is not settled science without caveats:

Effect sizes are modest: Critics note that one issue with the studies is that the relative risks are not very high—they are 1.1-fold to 1.5-fold increases.

Not all outcomes are equally supported: A 2024 umbrella review found weak to no evidence for many site-specific cancers, including breast, central nervous system, and pancreatic cancer, as well as for conditions such as hypertriglyceridemia, low HDL cholesterol, Crohn's disease, and non-alcoholic fatty liver disease.

Definitional problems: A core criticism is that the definition of "ultraprocessed" is ambiguous and frequently subjective—for example, a cake prepared by a home baker would be NOVA Category 3, but the same cake made industrially with a preservative becomes Category 4, even if nutritionally identical. Critics argue grouping diverse products into a single NOVA-4 UPF category oversimplifies the issue, ignoring key differences in their health effects.

Scientific polarization: As a recent Nature Food commentary noted, the strength of the evidence linking ultra-processed foods to adverse health outcomes polarizes the opinion of the scientific community. Some researchers argue skepticism is warranted and productive, while others counter that efforts to "manufacture scientific doubt" on the subject were similar to tactics used by the tobacco industry.

Bottom Line

The weight of current evidence—spanning large epidemiological cohorts, systematic reviews, and now emerging experimental/mechanistic studies—supports the conclusion that high UPF consumption is a genuine public health concern, particularly for cardiovascular disease, type 2 diabetes, obesity, and all-cause mortality. However, legitimate scientific debate persists over whether "processing" itself (versus the nutrients these foods typically contain—excess sugar, salt, saturated fat) is the causal driver, and over the practical usefulness of the NOVA classification for policy. Major health bodies (Lancet authors, NIH, American Heart Association) are now treating UPF as a priority public health issue warranting policy action, even as some nutrition scientists urge caution against over-simplifying a complex food system.