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A global analysis found that consumption of ultraprocessed food (UPF) is linked to premature deaths from all-cause mortality, demonstrating a linear dose–response relationship. As the proportion of UPFs in an individual’s total energy intake rises, so does the risk for premature death.

Despite knowing that the impact was expected to be high, “the numbers are significant,” lead author Eduardo Nilson, DSc, Oswaldo Cruz Foundation, Brasilia, Brazil, told Medscape Medical News.

Our findings suggest that some of these premature deaths could potentially be prevented “by reducing UPF consumption,” said Nilson.

UPFs are defined as ready-to-eat or heat industrial formulations that are made with ingredients extracted from foods or synthesized in laboratories, with little or no whole foods in their composition, according to the NOVA classification used for the analysis.

These foods are becoming dominant in the global food supply and “already account for over half of the average daily energy content of the diets in many high-income countries,” authors of the study wrote.

While consumption remains lower in low- and middle-income countries, “there is evidence that the exposure and adherence to a ultraprocessed dietary pattern has increased significantly over the last decades,” they added.

The study was published online in the American Journal of Preventive Medicine.

‘Public Health Concern’

Researchers modeled data from nationally representative dietary surveys as well as mortality data from Australia, Brazil, Canada, Chile, Colombia, Mexico, United Kingdom, and the United States to link dietary patterns to deaths from all causes.

They estimated a linear association between the dietary share of UPFs and all-cause mortality such that each 10% increase of UPFs in the diet increased the risk for death from all causes by 2.7%.

Then, using the relative risks (RRs) and the percentage of UPF consumption for each of the eight countries — which ranged from 15% of the total energy intake in Colombia to over 50% of calories in the United States — they estimated the proportion of premature deaths attributable to UPF consumption.

They found that the proportion of premature deaths attributable to UPF consumption ranged from approximately 4% in Colombia to 14% in both the United Kingdom and the United States. In the United States, for example, 124,000 premature deaths in 2018 were attributable to UPF consumption.

Limitations of the study model included the incorporation of inputs prone to residual confounding, use of similar RRs for all age and sex groups, and failure to capture the potential time lag between dietary changes and mortality.

Nevertheless, authors of the study wrote that their findings point to UPFs as a “public health concern.” They also called for national dietary guidelines to consider UPFs in their recommendations.

Reducing UPF consumption requires more than consumer education, Nilson noted. “Education by itself is insufficient to ensure healthy diets.”

Food choices are also influenced by price and availability, among other factors, he added.

To make healthy dietary patterns more accessible and affordable, countries must implement fiscal and regulatory policies, including subsidies for fresh and minimally processed foods and taxation of UPFs, Nilson suggested. And improvements in food labeling and regulation of food marketing and sales in schools, workplaces, and hospitals need to be made.

Furthermore, “policies must address all population groups,” he stressed. “For example, in Brazil, we know that adolescents consume more UPFs than adults.”

UPF: Culprit or Innocent Bystander?

In commentary provided by the Science Media Centre in response to the study, experts expressed concerns about the observational nature of the study and the methods that led to the authors’ conclusions, although they agreed that UPFs are likely linked to ill health.

“In my view, the NOVA system…has many limitations, including arbitrary definitions and overly broad food categories,” said Nerys Astbury, associate professor, Diet & Obesity, Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, England, who was not involved in the study.

There’s an “overemphasis of food ingredients as opposed to the processing per se,” and practical application of the system in accurately classifying foods is difficult, she added. “This is especially notable when attempting to classify foods from dietary data collected in large cohort studies, as in this study.”

Changing dietary guidelines based on this study is not warranted, according to Astbury. Many dietary recommendations already advise reducing the “consumption of energy-dense, high-fat, high-sugar foods, which typically fall into the UPF group,” she said. “Adding additional recommendations based on UPF could cause consumer confusion — some foods may be considered unhealthy by nutrient standards but not so by NOVA classification (and vice versa).”

Nita Forouhi, professor of population health and nutrition, MRC Epidemiology Unit, University of Cambridge, Cambridge, England, said that, despite issues with correlation vs causation, “well-conducted observational studies with long-term prospective cohort data are often the best we are going to get realistically.”

“So, we should not ignore such findings, especially as the current research has reported consistently similar associations in several countries, which increases the degree of confidence,” she added.

Similarly, Stephen Burgess, statistician in the MRC Biostatistics Unit, University of Cambridge, commented, “This type of research cannot prove that consumption of UPFs is harmful, but it does provide evidence linking consumption with poorer health outcomes.”

“It is possible that the true causal risk factor is not UPFs, but a related risk factor such as better physical fitness,” he said. But when we see these associations replicated across many countries and cultures, it raises suspicion that UPFs may be more than an innocent bystander.

The study was supported by the National Council for Scientific and Technological Development and the Fundação de Amparo à Pesquisa do Estado de São Paulo, in Brazil. Nilson, Forouhi, Astbury, and Burgess declared no conflicts of interest.

Marilynn Larkin, MA, is an award-winning medical writer and editor whose work has appeared in numerous publications, including Medscape Medical News and its sister publication MDedge, The Lancet (where she was a contributing editor), and Reuters Health.