Two distinct patterns of molecules in the blood linked to an ultra-processed diet and a minimally processed diet have been identified in a new study by UCL (University College London) and Imperial College London researchers.
The study, published in the journal BMC Medicine , involved data from more than 6,000 adults in the UK who had blood tests and filled in questionnaires about their diet and whose health was then tracked for up 20 years.
The researchers looked at patterns of metabolites – tiny molecules the body makes as it processes food and carries out other chemical reactions. They measured 233 metabolites in the blood and used machine learning to identify the metabolites most strongly linked to each diet.
They found that molecules linked to the ultra-processed diet included more unhealthy fats and lower levels of healthy fats such as omega-3 fatty acids, while a minimally processed diet had the opposite pattern.
The team also found that this biological signature accounted for up to half (43% to 51%) of the link between diet and a person’s risk of developing heart disease and type 2 diabetes. This link to disease remained even after accounting for the higher levels of sugar, fat and salt present in the ultra-processed diets studied.
Lead author Dr Eunice Wang, who carried out the work while a PhD student at UCL Epidemiology & Public Health, said: “We know there is a link between ultra-processed food and disease, but there is uncertainty over what is driving this connection - whether it is due to higher levels of sugar, salt and saturated fat, as well as dense calorie content, or whether the risks also come from food processing. Our findings hint that processing itself may play a role, although more research is needed to support this.”
The UK’s Scientific Advisory Committee on Nutrition (SACN), the independent committee that advises the government, is currently weighing evidence on the health impact of ultra-processed foods.
Senior author Professor Clare Llewellyn (UCL Behavioural Science and Health) said: “Current UK dietary guidance does not consider processing itself as a risk but recommends a reduced intake of foods high in ingredients such as sugar, salt and saturated fat.
“This study, which is the first to compare metabolic signatures of ultra processed and minimally processed diets, adds to the evidence needed to inform future policy discussions about whether the degree of processing should be considered alongside nutritional profile, when assessing the health implications of foods.”
The team used data from the Whitehall II cohort study of British civil servants who were recruited in the 1980s and whose health was tracked for decades.
Over 20 years, those in the highest third of ultra-processed food intake had a 17% higher risk of developing cardiovascular disease than those in the lowest third.
Meanwhile, the third of participants who had the highest intake of minimally processed food had a 19% lower risk of cardiovascular disease and a 40% lower risk of type 2 diabetes than those in the lowest third.
Metabolites in the blood were measured using a technique called nuclear magnetic resonance (NMR) spectroscopy. With the help of a machine learning tool, the researchers identified 34 metabolites most closely linked to an ultra-processed diet and 50 linked to a minimally processed diet. Eight metabolites were present in both groups.
The pattern of metabolites linked to an ultra-processed diet included lower levels of omega-3 fatty acids and high-density lipoprotein (HDL), sometimes known as “good” cholesterol, and higher levels of triglycerides carried by very low density lipoproteins (VLDLs) – the type of blood fats that, in excess, contribute to clogged arteries.
The researchers also gave each participant a score based on how closely their pattern of metabolites matched the signatures of each diet. They compared these scores with later disease outcomes to assess how much these metabolite profiles accounted for the link between diet and disease.
The metabolite profile for ultra-processed food accounted for 51% of the link with later cardiovascular disease, and 43% of the link with type 2 diabetes.
The unexplained part of the link, the researchers said, might be accounted for by influences on gut microbes, inflammation in the body, or changes in appetite and fullness signals – factors not captured by measuring blood metabolites.
The team also looked at how much specific ingredients in diet may have contributed to the disease links. They found that salt and saturated fat did not appear to affect risks of either cardiovascular disease or type 2 diabetes. For diabetes alone, sugar did account for some of the disease link – an estimated 27%.
Among study limitations, the researchers noted that, as it was an observational study, it could not determine cause and effect. Study strengths included longer follow-up of participants compared to other, similar studies.
BMC Medicine
Circulating metabolomic signatures of ultra-processed and minimally processed food intake and risk of cardiovascular disease and type 2 diabetes: 20-year follow-up in the Whitehall II cohort
25-Sep-2026