What ultra-processed food is
The NOVA classification system, developed by Brazilian researchers, categorises foods into four groups: unprocessed or minimally processed (fresh fruit, vegetables, meat, eggs), processed culinary ingredients (salt, oils, flour), processed foods (canned vegetables, cheese, cured meats) and ultra-processed foods — industrially produced formulations made mostly or entirely from processed food substances with the addition of flavourings, colouring, emulsifiers and other additives not typically used in home cooking.
What the research shows
Several large prospective cohort studies — following large populations over years — have found associations between high UPF consumption and adverse health outcomes including obesity, type 2 diabetes, cardiovascular disease, depression and all-cause mortality. A 2022 IARC study found that each 10% increase in the proportion of UPF in the diet was associated with a 15% increase in the risk of any cancer.
The causation question
These are observational studies and cannot establish causation. People who eat more UPF may differ from people who eat less in many other ways that affect health. The first randomised controlled trial on UPF — published in 2019 — did find that people assigned to a UPF diet consumed more calories and gained more weight than those on an unprocessed food diet, but the mechanism remains debated.
The nuance
Not all UPF is equivalent. The category includes soft drinks and reconstituted meat products, but also packaged wholegrain bread, fortified breakfast cereals and some yoghurts. Blanket advice to avoid all UPF is both impractical for many households (UPF is typically cheaper and more convenient) and potentially misdirected. A focus on overall dietary quality — plenty of vegetables, fruit, legumes and whole grains — is more actionable.