Are ultra-processed foods a public health hazard?

Are Ultra-Processed Foods a Public Health Hazard?

The weight of current scientific evidence strongly supports the view that ultra-processed foods (UPFs) pose a genuine public health hazard, though important debates about mechanisms and classification remain.

The Case That They Are a Hazard

Mortality and disease risk. Multiple large-scale meta-analyses converge on similar findings. A 2025 dose-response meta-analysis of over 1.1 million participants found 18 studies with 1,148,387 participants and 173,107 deaths showed that compared to the lowest, participants with the highest UPF consumption had a 15% increased risk of all-cause mortality. An earlier meta-analysis of over 200,000 participants found UPF consumption was related to an enhanced risk of all-cause mortality (HR = 1.21), cardiovascular disease mortality (HR = 1.50), and heart-cause mortality (HR = 1.66), with each 10% increase in UPF consumption in daily calorie intake associated with a 15% higher risk of all-cause mortality.

A very large recent review reinforces this: each additional 100 g/day of UPF intake was associated with higher risks of cardiovascular events, cancer, all-cause mortality and metabolic syndrome/diabetes, in an analysis covering more than 8 million people.

Beyond observational data—causal evidence is emerging. 2025 marked a turning point, with growing evidence linking ultra-processed food consumption to chronic disease risk, and experimental, clinical and epidemiological studies converging to elucidate the underlying mechanisms. Notably, a 2025 randomized controlled trial showed harmful effects of UPFs on weight gain and metabolic and reproductive health, regardless of excessive caloric intake—suggesting processing itself, not just calories, drives harm. Complementing this, controlled feeding trials demonstrate that processing per se can drive excess calorie consumption and adverse metabolic responses.

Possible mechanisms. Research points to food additives as one culprit: multiple factors are suspected to explain detrimental effects of UPFs, beyond their nutritional profile, including food additives. Animal studies found that two widely consumed food additive emulsifiers caused transgenerational microbiota alteration that led to increased long-term susceptibility to metabolic and inflammatory diseases—concerning because safety assessments of food additives have been performed substance by substance, while mixtures of additives are consumed daily by billions of people worldwide.

Major scientific consensus statements. A landmark 2025 Lancet Series concluded that the evidence about the increase in ultra-processed foods in diets globally highlights the association with many non-communicable diseases, driven by powerful global corporations who employ sophisticated political tactics to protect and maximise profits. The authors explicitly argue that although more research on UPFs will continue to be valuable, the current science is already strong enough to justify immediate public health action, since waiting for further studies would allow UPFs to gain an even stronger hold in global diets.

Policy responses reflect this consensus. Governments are acting: in June, California voted to enact the first U.S. law to define and ban unhealthy ultra-processed foods from an estimated over 1 billion meals served to California schoolchildren in the 2025–2026 school year.

Important Caveats and Scientific Debate

Not everyone agrees the picture is settled, and there are legitimate methodological critiques worth noting.

Classification problems. Critics point out that the concept of ultra-processed foods is multidimensional, encompassing variation in nutritional composition, ingredients, processing methods and additive profiles. A recent critical review found substantial heterogeneity in health outcomes across UPF subtypes, with products like sugar-sweetened beverages consistently associated with adverse outcomes while fortified cereals and certain dairy products demonstrate neutral or protective effects. The NOVA system's binary nature fails to account for nutritional composition, fortification benefits, and cultural food traditions, creating inconsistencies in categorisation across different contexts.

Confounding and study design issues. Skeptics note dietary assessment limitations, Nova classification ambiguities and residual confounding affect causal inference in epidemiological studies and short-term interventions. Similarly, another review flagged inadequate dietary assessment tools, selective reporting of negative findings, and experimental design flaws that conflate processing with other dietary factors.

Not all "unprocessed" foods are safe either. One critique notes the irony that red meat, often eaten as a steak, is an unprocessed or minimally processed food, yet its intake is associated with increased cardiovascular mortality and several types of cancer—highlighting that processing level alone doesn't fully capture health risk.

Bottom Line

Despite legitimate scientific debate over why and exactly which UPFs are harmful, the convergence of large epidemiological cohorts, dose-response meta-analyses, emerging RCT evidence, and mechanistic studies has led major bodies (WHO, UNICEF, and Lancet Series authors) to treat UPFs as a genuine and urgent public health concern—one serious enough to prompt binding policy action like California's school food law. The strongest, most consistent evidence points to sugar-sweetened beverages and heavily processed snack foods, while some UPF subcategories (fortified cereals, certain dairy) appear less harmful—suggesting the hazard is real but not uniform across all foods captured by current classification systems.