Are ultra-processed foods a public health hazard?

Ultra-processed foods and public health is a fast-moving debate — I'll pull the latest evidence on their health risks and what health agencies advise.

Yes - the balance of current evidence suggests high consumption of ultra-processed foods (UPFs) is a public health hazard, although scientific debate remains about whether it is "processing" itself or the nutritional profile of these foods that drives risk.

1. What are ultra-processed foods?

The most widely used definition comes from the NOVA classification system, developed by Professor Carlos Monteiro and colleagues in Brazil.

NOVA describes UPFs as 'formulations of ingredients, mostly of exclusive industrial use, typically created by a series of industrial techniques and processes (hence 'ultraprocessed')', 'formulated mostly or entirely from substances extracted from foods' and made possible by additives that imitate or enhance sensory qualities.

In practical terms, they are ready-to-eat products such as deli meat, microwaveable dinners, chips, frozen pizza, cereal, sugary drinks and other prepackaged items, typically described as 'formulated from industrial ingredients and contain little or no intact foods'.

This definition is broad and captures many foods that have a poor nutritional profile, are energy dense and high in fat, sugars and salt. They are typically unhealthy due to high contents of fat, sugar and salt, and low contents of fiber, protein and micronutrients.

UPFs make up a large share of modern diets:

2. Evidence linking UPFs to adverse health outcomes

Large-scale reviews

The largest synthesis to date is an umbrella review published Feb 28, 2024 in The BMJ, which reviewed 45 meta-analyses involving about 10 million people in total. Similar summaries describe it as pooling 45 meta-analyses covering almost 10 million people and finding direct associations between exposure to ultra-processed foods and 32 health parameters including mortality, cancer, and mental, respiratory, cardiovascular, gastrointestinal, and metabolic ill health.

On the basis of the random effects model, 32 (71%) distinct pooled analyses showed direct associations and higher exposure was associated with a higher risk of adverse health outcomes, especially cardiometabolic, common mental disorder, and mortality outcomes.

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. Consistent evidence shows that higher exposure is associated with increased risk of 32 damaging health outcomes including cancer, major heart and lung conditions, mental health disorders, and early death.

Other pooled analyses found:

Recent individual studies

Health organizations worldwide, such as the World Health Organization and the American Heart Association, recommend reducing intake of ultra-processed foods to lower risk of heart disease, advocating diets rich in fruits, vegetables, whole grains, and lean proteins. WHO and the International Agency for Research on Cancer endorse public health strategies to limit intake of components commonly present in ultra-processed foods, including high levels of added sugar and non-sugar sweeteners.

3. Proposed mechanisms

4. Nuance and debate - Is all UPF equally hazardous?

Major reviews and expert bodies stress that the evidence is largely observational and cannot prove causality.

A number of countries advise reduction of UPF within national dietary guidelines based on evidence, largely from observational studies, linking high intakes with poor outcomes including heart disease, type 2 diabetes, obesity and cancer. Although such studies have shown consistent associations, it is difficult to untangle the impact of less healthy dietary patterns and lifestyles and they do not provide clear evidence of a causal association between processing per se and health.

Critics argue:

The British Nutrition Foundation notes that blanket advice to avoid UPF may have unintended consequences including guilt and stigma, implying people must spend more on unprocessed foods and more time cooking, when some UPF foods such as vegetable-based sauces can aid preparation of low-cost nutritious meals, and that demonising all processed foods could adversely impact intake of more affordable sources of nutrients.

The American Heart Association scientific advisory and other experts argue not all UPFs are bad; certain processing methods help keep foods safe, nutritious, and affordable, and subgroups like whole-grain bread and pastas, canned/frozen fruits and vegetables, fortified cereals and yogurt can have health benefits.

The worst culprits consistently identified are sugary beverages, processed meats (hot dogs, sausages, deli meats preserved with nitrates/nitrites classified as Group 1 carcinogens), salty snacks, and products with trans fats and hydrogenated oils that increase LDL cholesterol and promote atherosclerosis.

5. Public health perspective

Given consistent associations across mortality, cancer, mental, respiratory, cardiovascular, gastrointestinal and metabolic ill health, many researchers conclude findings may provide support for public health measures to minimise ultra-processed food exposure, including taxation of sugar-sweetened beverages and subsidies for healthier options, marketing restrictions, and front-of-pack labelling indicating level of processing.

At the same time, UK policy does not currently include UPF in government dietary recommendations, with the British Nutrition Foundation stating at present there is no agreed definition and they are not referred to in recommendations, and that due to lack of agreed definition and need for better understanding of mechanisms, UPF does not warrant inclusion within policy. Authors of the BMJ umbrella review also call for urgent research to understand how ultra-processed foods affect health.

Bottom line: High intake of ultra-processed foods — especially sugar-sweetened drinks, processed meats, and salty/fried snacks high in added sugars, salt and unhealthy fats — is consistently associated with higher risk of obesity, cardiovascular disease, type 2 diabetes, depression, and premature death, making excessive UPF consumption a recognized public health hazard. The hazard appears driven more by poor nutritional quality, energy density, and additives displacing healthier foods than by industrial processing as an independent toxic exposure, meaning not every food labelled "ultra-processed" carries the same risk.