Are ultra-processed foods a public health hazard?

Based on the current body of evidence, ultra-processed foods (UPFs) are widely regarded by public health researchers as a significant health hazard, though important scientific caveats remain about causation and classification.

The evidence for harm

The strongest evidence comes from a landmark 2024 umbrella review. That's the number of health problems noted in the largest-ever review of studies about the dangers of diets high in ultra-processed foods. The findings, published online Feb. 28, 2024, by The BMJ, come from a review of 45 analyses published in the last three years, involving about 10 million people in total. When scientists graded the evidence, they 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. Associations between ultra-processed foods and asthma, gastrointestinal disease, some cancers, and other health issues were limited, the authors say, and need further investigation.

This is reinforced by other large analyses. One meta-analysis of nearly 200,000 participants found highest UPF consumption was found to be associated with increased risk of all-cause mortality in five studies, increased risk of CVD in three studies, cerebrovascular disease in two studies, and depression in two studies.

Emerging research is also linking UPFs to conditions like chronic kidney disease—higher UPF intake was significantly associated with increased CKD risk—and even Alzheimer's disease, where 4 demonstrated a risk association between the consumption of ultra-processed foods and the development of Alzheimer's disease.

A major new three-part Lancet series (2025) goes further, arguing the case for a causal, biological pathway. It points to 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 as mechanisms explaining why UPFs harm health beyond just poor nutrient profiles.

Important scientific caveats

Despite this alarming picture, researchers urge caution for several reasons:

1. Most evidence is observational, not causal. A 2023 meta-analysis 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. However, these risks varied significantly depending on the methodology used to assess UPF consumption, with a difference of more than 50% between the methods. The authors concluded caution should be used when interpreting and extrapolating the results.

2. The NOVA classification itself is contested. Critics argue the assumption that all UPFs are uniformly harmful warrants critical examination... a review of evidence revealed 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. They also point out that the binary nature of NOVA's classification fails to account for nutritional composition, fortification benefits, and cultural food traditions, creating inconsistencies in categorisation across different contexts.

3. Methodological weaknesses persist. Reviewers note methodological limitations in UPF research include inadequate dietary assessment tools, selective reporting of negative findings, and experimental design flaws that conflate processing with other dietary factors.

4. Industry and policy tensions. One analysis pointed out that a UK parliamentary briefing classified some associations as 'convincing evidence' but underplayed data from challenge and mechanistic studies and concluded that more research was required before public health policies can be formulated. Industry has sometimes influenced scientific research and public narrative.

Bottom line

The weight of evidence—spanning dozens of meta-analyses and tens of millions of participants—consistently links high UPF consumption with elevated risks of obesity, type 2 diabetes, cardiovascular disease, certain cancers, depression, and premature death. This has led major public health bodies and a growing number of nutrition scientists to treat UPFs as a genuine public health concern deserving of policy attention (e.g., taxes, marketing restrictions, reformulation incentives). However, the field has not fully resolved whether "processing" itself is the causal culprit, or whether UPFs are simply a convenient proxy for foods that are high in sugar, salt, refined carbs, and low in fiber. The category is also so broad that it lumps together products (like a sugary soda and a fortified whole-grain bread) with likely very different health effects—so blanket avoidance advice may be an oversimplification even as the overall pattern of harm looks real.