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Lancet study links UPFs to chronic disease risk

UPFs are consistently associated with an increased risk of diet-related chronic diseases, according to a comprehensive review of global evidence in The Lancet .

Published in mid-November, the first paper in a three-part series on ultra-processed food (UPF) research and policy offers the most extensive synthesis to date of cohort studies, national surveys, sales data, and mechanistic evidence on their health impacts.

Led by Professor Carlos Monteiro, the authors argue that the expansion of UPFs has displaced traditional food-based diets in many countries, creating a global dietary pattern marked by nutrient imbalance and rising chronic disease prevalence, including type 2 diabetes, cardiovascular disease, and depression.

Defined under the Nova classification system, originally developed by Monteiro, UPFs are formulations of industrial ingredients such as protein isolates, modified starches, non-nutritive sweeteners, and emulsifiers, designed for shelf stability and sensory appeal, but typically low in fibre and micronutrients and high in added sugar, salt, and saturated fat.

“The totality of the evidence supports the thesis that displacement of long-established dietary patterns by ultra-processed foods is a key driver of the escalating global burden of multiple diet-related chronic diseases,” the authors wrote.

UPF and disease risk: A growing body of evidence

While the review identifies strong associations between UPF consumption and a wide range of health outcomes, it stops short of asserting direct causality.

The authors noted that most of the studies included are observational, with limited data from controlled trials.

Responding to the publication, Professor Martin Warren, chief scientific officer at the Quadram Institute, said the evidence convincingly shows that UPFs have displaced traditional diets and that high-UPF diets correlate with poor nutrient quality.

However, he questioned the strength of the paper’s causal claims.

“The link between UPFs and chronic disease remains associative; the causal chain is incomplete,” he said. “It remains unclear whether the observed risks derive from components common to energy-dense UPFs, from what UPF-heavy diets lack, or from the combination of both.”

This caution was echoed by Professor Kevin McConway, emeritus professor of applied statistics at the Open University, who noted that some of the studies reviewed relied on dietary data collected before the introduction of the Nova classification system.

“This must cast some doubt on studies that used older methods of measuring diet, and that relates to some of the evidence for all three hypotheses,” he said.

“Further research using better dietary measurement might well not lead to different conclusions – but actually, we don’t know whether that’s the case until and unless the research is carried out using the new measures.”

How processing affects health

A key criticism of the Nova system has long been that by classifying foods based on processing rather than nutrient content, this methodology groups products with varying nutritional profiles, such as flavoured yoghurt and sugary beverages, into the same category.

While the paper acknowledges critiques of Nova’s scope and granularity, it defends the classification’s policy utility. UPFs, it argues, differ from traditional processed foods not only in composition but in their function within food systems, where they displace whole and minimally processed foods and promote overconsumption.

Professor Jules Griffin, of the Rowett Institute, agreed that the evidence points to consistent associations between UPF intake and adverse health outcomes across diverse regions.

“Despite... reservations with the understanding of mechanisms that UPF may cause ill health, the overall message is that we urgently need to understand how food processing on this scale influences our health and how ultra-processed food has a major impact on our risk of developing chronic diseases,” he said.

Calls for policy intervention

The paper concludes by recommending precautionary action to reduce UPF consumption. It suggests integrating UPF indicators into national dietary guidelines, front-of-pack labelling, and taxation models, as some countries in Latin America have already done.

Dr Hilda Mulrooney, reader in nutrition and health at London Metropolitan University, supported this approach.

“Given the disproportionate risks of chronic disease to the most disadvantaged groups, and the costs of poor diet to individuals and health systems, it is beyond time to act,” she said.

However, other experts warned that such policies must consider affordability and access. UPFs are often cheaper and more widely available than minimally processed foods, particularly in low-income settings.

“Although the papers touch on affordability and access, they do not fully capture the structural realities,” Warren said. “UPFs are cheap, convenient, aggressively marketed, and often the only realistic option for people with limited time, money, or cooking facilities...

“Designing interventions that meaningfully shift eating patterns, particularly for those most constrained by circumstance, remains an immense challenge.”