Are ultra-processed foods a public health hazard?

Yes — the weight of current scientific evidence strongly supports classifying ultra-processed foods (UPFs) as a public health hazard, though researchers are still working out the exact mechanisms and some methodological debates remain.

What counts as "ultra-processed"

UPFs are generally defined as ready-to-eat or ready-to-heat industrial preparations made largely or entirely with substances extracted from food, often chemically modified, with additives, and with a small proportion of whole food. Not all processing is equal: most of the food we eat is processed in some way, whether it's chopped, canned, heated or frozen, and these types of processing can actually help us create healthy diets by making some food safer to eat or easier to store and cook. UPFs are a distinct category — think packaged snacks, sodas, and frozen ready meals.

Scale of the problem

UPFs now dominate diets in many countries. Such food now accounts for nearly 60% of U.S. adults' calorie consumption, and among American children, that portion is close to 70%. Globally, the industry has grown enormously: global UPF sales grew from $1.5 trillion in 2009 to $1.9 trillion in 2023.

The epidemiological evidence

The observational evidence linking UPFs to poor health is extensive and consistent. A major umbrella review found that high UPF consumption is associated with an increased risk of a variety of chronic diseases and mental health disorders, and at present, not a single study reported an association between UPF intake and a beneficial health outcome. More specifically, that review identified renal function decline and wheezing in children and adolescents as showing convincing evidence (Class I), with diabetes mellitus, overweight, obesity, depression, and common mental disorders showing highly suggestive evidence (Class II).

A 2024 umbrella review covering nearly 10 million participants found "convincing" evidence that a diet high in ultra-processed foods increases the risk of death from cardiovascular disease by 50% and the risk of anxiety by 48%. Beyond cardiometabolic disease, dozens of studies have provided evidence suggesting that high ultra-processed food consumption is associated with a range of adverse health outcomes, including obesity, metabolic syndrome, heart disease, cerebrovascular disease, depression, anxiety, cancer and mortality from all causes.

More recent research has extended these associations further, tying UPF intake to early signs of Parkinson's disease, cognitive decline and stroke risk, and even autoimmune conditions like systemic lupus erythematosus and rheumatoid arthritis. The 2025 Lancet Series concluded that this evidence is substantiated by more than 100 prospective studies, meta-analyses, randomised controlled trials, and mechanistic studies, covering adverse outcomes across nearly all organ systems.

Moving beyond correlation: causal mechanisms

Critics have long argued that UPFs are simply proxies for foods high in sugar, salt, and fat — not that "processing" itself is the problem. However, newer experimental work is addressing this. A 2025 randomized controlled trial has shown the harmful effects of UPFs on weight gain and metabolic and reproductive health, regardless of excessive caloric intake. Another trial found that ultra-processed foods cause weight gain and increased energy intake associated with reduced chewing frequency — suggesting texture and food matrix effects independent of nutrient content.

Additive-related mechanisms are also emerging: in mice, two widely consumed food additive emulsifiers caused transgenerational microbiota alteration that led to increased long-term susceptibility to metabolic and inflammatory diseases. Importantly, safety assessments of food additives have so far been performed substance by substance, while mixtures of additives are consumed daily by billions of people worldwide — a regulatory blind spot.

The 2025 Lancet Series frames the broader picture this way: UPF-driven dietary change causes deterioration of diet quality... gross nutrient imbalances; overeating driven by high energy density, hyper-palatability, soft texture, and disrupted food matrices; reduced intake of health-protective phytochemicals; and increased intake of toxic compounds, endocrine disruptors, and potentially harmful classes and mixtures of food additives.

Important caveats

The evidence isn't without limitations. One meta-analysis on cardiometabolic outcomes noted that a consistently positive association between high UPF intake and increased risk of developing diabetes, hypertension, hypertriglyceridemia, low HDL cholesterol, and obesity was observed, even if the quality of evidence was not satisfying... these risks varied significantly depending on the methodology used to assess UPF consumption, and the authors concluded that caution should be used when interpreting and extrapolating the results.

Similarly, a systematic review of intervention trials found mixed results: interventions aimed at reducing the consumption of UPFs showed benefits on some anthropometric and dietary intake outcomes, although significant effects were not observed for most of the evaluated outcomes.

The policy and industry angle

Public health experts increasingly frame this as a systemic, not just individual, problem. The Lancet Series argues that this rise in ultra-processed foods is driven by powerful global corporations who employ sophisticated political tactics to protect and maximise profits, and education and relying on behaviour change by individuals is insufficient — deteriorating diets are an urgent public health threat that requires coordinated policies and advocacy.

Some researchers explicitly compare the situation to tobacco control, noting the global pandemic of diet-related disease is increasingly recognised as commerciogenic — driven by financial incentives in the food system — despite international consensus on the harms of UPF and the adoption of precautionary policies by organisations such as WHO, UNICEF and governments in Latin America, while regulatory conflicts of interest persist in other countries.

U.S. regulators have taken notice: in 2025, HHS, FDA and USDA announced work toward a uniform definition of ultra-processed foods to allow for consistency in research and policy, alongside investing in high-quality research through the FDA's Nutrition Regulatory Science Program.

Bottom line

The evidence base — spanning large cohort studies, umbrella reviews, and an increasing number of mechanistic and randomized trials — consistently points to UPFs as harmful to cardiometabolic, mental, and even reproductive health, largely because they degrade diet quality and may have effects (via additives, texture, and food matrix disruption) independent of simple nutrient content. While debate continues over precise causal pathways and the quality of some observational evidence, the consensus among major public health bodies and journals like The Lancet is that current UPF consumption patterns constitute a genuine and urgent public health threat requiring policy-level intervention, not just individual dietary choices.