Are ultra-processed foods a public health hazard?

Short answer: Yes, the evidence strongly suggests ultra-processed foods (UPFs) pose significant public health risks — though important debates remain about mechanisms and whether all UPFs are equally harmful.

The evidence is substantial and growing

Large-scale reviews consistently link high UPF consumption to numerous chronic diseases. A 2024 umbrella review of 45 meta-analyses including almost 10 million people found that diets high in UPFs are linked to 32 health conditions, including obesity, type 2 diabetes, cardiometabolic diseases, many cancers, gastrointestinal disorders, asthma, anxiety, depression, cardiovascular events, and all-cause mortality.

The strength of evidence varies by outcome. A 2024 umbrella systematic review and meta-analysis found convincing evidence that higher UPF intake was associated with increased risk of cardiovascular disease related mortality, Type 2 diabetes, as well as anxiety and other combined common mental disorder outcomes. The review also found highly suggestive evidence that linked UPF intake to all-cause mortality, heart disease related mortality, depressive symptoms and obesity. More specifically, a 2024 review of 45 metanalyses 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%, and "highly suggestive" evidence linking it to a 66% higher risk of death from heart disease, 55% higher obesity risk, and 40% higher Type 2 diabetes risk.

Notably, weak to no evidence was found for many site-specific cancers, and for conditions such as hypertriglyceridemia, low HDL cholesterol, Crohn's disease, ulcerative colitis, and metabolic syndrome — showing the links aren't universal across every disease category.

2025 brought a turning point: causal evidence, not just correlation

Until recently, most evidence was observational (showing association, not proof of causation). That changed in 2025: experimental, clinical and epidemiological studies converged to elucidate the underlying mechanisms at play. Specifically, 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 — meaning UPFs may harm health through mechanisms beyond just calories.

Researchers are also identifying specific culprits. 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 mellitus incidence.

Real-world scale of the problem

This isn't a niche issue — more than half of the calories that the average American adult consumes are from ultra-processed foods. Global health experts have responded accordingly: global experts warn that ultra-processed foods are driving rising disease rates and demand urgent, worldwide policy action.

Important caveats: Not all UPFs are created equal

Critics argue the NOVA classification system is too blunt an instrument. While overall UPF consumption was associated with increased CVD risk, individual UPF categories exhibited strikingly divergent patterns — sugar-sweetened beverages and processed meats consistently showed adverse associations, while bread products, cold cereals, yoghurt/dairy desserts, and certain savoury snacks demonstrated inverse associations with CVD risk.

Scientists also debate what's actually driving the harm. Major controversies concern the Nova classification system, substantial heterogeneity within the UPF category, challenges in reproducible classification, and the extent to which observed associations reflect processing itself rather than nutrient profile, dietary patterns, or broader food environments. Leading hypotheses for why UPFs might be harmful beyond simple nutrient content include poor nutrient profiles, displacement of minimally processed foods from the diet, and alterations to physical structure that impact how UPFs are consumed.

There's also a practical problem: even if UPFs are harmful, surveys across multiple countries suggest that consumers have limited and often inaccurate understanding of the Nova classification system and the concept of UPF, frequently interpreting it in terms of nutrient content rather than processing level — complicating public health messaging.

Bottom line

The weight of scientific evidence — spanning observational cohorts, mechanistic studies, and now randomized controlled trials — supports treating heavily ultra-processed diets as a genuine public health concern, particularly for cardiovascular disease, type 2 diabetes, obesity, and mental health outcomes. However, the relationship is nuanced: not all foods technically classified as "ultra-processed" carry equal risk, and scientists are still working out exactly which components (additives, lack of fiber, altered food structure, nutrient profile) drive the harm. This has led major health bodies to call for policy action while also cautioning against treating the entire UPF category as uniformly dangerous.