Eating large quantities of ultra-processed (UPF) food has been associated with a higher risk of developing cancers of the upper digestive tract, like mouth, throat and oesophageal cancer, according to a recent study.
In the study, people who consumed 10% more ultra-processed foods than others had a 23% higher risk of head and neck cancer and a 24% higher risk of oesophageal adenocarcinoma, a cancer that grows in the glands lining the insides of organs, said Dr Helen Croker, assistant director of research and policy at World Cancer Research Fund International, which funded the study.
More research and data collection are needed to understand the link in the report, said co-author Dr Ingre Huybrechts, a nutritional epidemiologist in the Nutrition and Metabolism Branch at the International Agency for Research on Cancer, which helped sponsor the study.
The dietary data was collected in the 1990s, when the consumption of UPFs was still relatively low, Huybrechts told CNN. “As such, associations may potentially be stronger in cohorts including recent dietary follow-up assessments.”
UPF foods, like sodas, chips, nuggets, packaged soups, ice cream and more, contain ingredients never or rarely used in kitchens, or classes of additives whose function is to make the final product palatable or more appealing, including preservatives to resist mould and bacteria; emulsifiers to keep incompatible ingredients from separating; artificial colourings and dyes; anti-foaming, bulking, bleaching, gelling and glazing agents; and added or altered sugar, salt and fats designed to make food more appealing.
Body fat as a risk factor
The latest study, published in the European Journal of Nutrition, analysed diet and lifestyle data, including questions on UPF consumption, on 450 111 adults who were participating in the European Prospective Investigation into Cancer and Nutrition, or EPIC.
One of the largest such studies in Europe, EPIC recruited participants between 1992 and 1999 from 23 centres across 10 European countries and the United Kingdom.
Being overweight or obese is a well-known risk factor for developing at least 13 types of cancer, including cancer of the oesophagus, according to the US Centres for Disease Control and Prevention.
Ultra-processed foods are often considered to be a driver of excess weight, but after performing statistical analysis on the results, however, researchers found increases in body fat accounted for only some of the statistical association between UPF and cancers of the upper digestive tract over a 14-year period.
An increased waist-to-hip ratio only explained 5% of the 23% higher risk for head and neck cancer, found the study. An increase of body mass index, or BMI, explained 13% of the 24% additional risk for oesophageal cancer, while waist-to-hip ratio explained 15%.
“In other words, if UPFs contribute to cancer risk, they do it to a small extent by contributing to obesity, and to a much larger extent by other mechanisms,” said Dr David Katz, a specialist in preventive and lifestyle medicine who was not involved in the study.
It’s possible that ingredients like emulsifiers, preservatives, artificial sweeteners and toxins found in food packaging might also play a role in the link between UPF and cancer or other diseases, the study authors said.
An unusual link
Oddly, the study also found a link between ultra-processed food and accidental deaths, which was being used as a control for the study.
“The researchers used accidental death as a ‘negative control’ i.e, something with which UPFs should not be associated if only direct impacts were being tallied,” Katz said.
“UPFs were, however, associated with a higher rate of accidental death – suggesting that UPFs are a marker for adverse circumstances in general. Among the factors that might contribute to this association are poverty, discrimination, environmental blight and so on.”
Therefore, it’s not clear just what is behind the link, said study co-author Dr George Davey Smith, a professor of clinical epidemiology at the University of Bristol in the UK.
“UPFs are clearly associated with many adverse health outcomes, yet whether they actually cause these, or whether underlying factors such as general health-related behaviours and socio-economic position are responsible for the link, is still unclear,” he said.
Study details
Ultra-processed foods, adiposity and risk of head and neck cancer and oesophageal adenocarcinoma in the European Prospective Investigation into Cancer and Nutrition study: a mediation analysis
Fernanda Morales-Berstein, Carine Biessy, Inge Huybrechts, et al.
Published in European Journal of Nutrition on 22 November 2023
Abstract
Purpose
To investigate the role of adiposity in the associations between ultra-processed food (UPF) consumption and head and neck cancer (HNC) and oesophageal adenocarcinoma (OAC) in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort.
Methods
Our study included 450,111 EPIC participants. We used Cox regressions to investigate the associations between the consumption of UPFs and HNC and OAC risk. A mediation analysis was performed to assess the role of body mass index (BMI) and waist-to-hip ratio (WHR) in these associations. In sensitivity analyses, we investigated accidental death as a negative control outcome.
Results
During a mean follow-up of 14.13 ± 3.98 years, 910 and 215 participants developed HNC and OAC, respectively. A 10% g/d higher consumption of UPFs was associated with an increased risk of HNC (hazard ratio [HR] = 1.23, 95% confidence interval [CI] 1.14–1.34) and OAC (HR = 1.24, 95% CI 1.05–1.47). WHR mediated 5% (95% CI 3–10%) of the association between the consumption of UPFs and HNC risk, while BMI and WHR, respectively, mediated 13% (95% CI 6–53%) and 15% (95% CI 8–72%) of the association between the consumption of UPFs and OAC risk. UPF consumption was positively associated with accidental death in the negative control analysis.
Conclusions
We reaffirmed that higher UPF consumption is associated with greater risk of HNC and OAC in EPIC. The proportion mediated via adiposity was small. Further research is required to investigate other mechanisms that may be at play (if there is indeed any causal effect of UPF consumption on these cancers).
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