Eating more ultra-processed foods (UPFs) may be associated with a higher risk of developing cancer of the upper respiratory and digestive tract (including the mouth, throat and esophagus), according to a new study led by researchers at the University of Bristol and the International Agency for Research on Cancer (IARC).
The authors of this international study, which analyzed the diet and lifestyle data of 450,111 adults who were followed for about 14 years, say obesity associated with the consumption of UPFs may not be the only culprit factor. The study was published today [22 Nov] in the European Journal of Nutrition.
Several studies have shown a link between consumption of UPFs and cancer, including a recent study that looked at the link between UPFs and 34 different cancers in the largest cohort study in Europe, the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort.
As more evidence emerges about the associations between eating UPFs and adverse health outcomes, researchers from Bristol Medical School and the IARC wanted to investigate this further. Because many UPFs have an unhealthy nutritional profile, the team sought to determine whether the association between UPF consumption and head and neck cancer and esophageal adenocarcinoma (a cancer of the esophagus) in EPIC could be explained by an increase in body fat.
Results from the team’s analyzes showed that eating 10% more UPFs is associated with a 23% higher risk of head and neck cancer and a 24% higher risk of esophageal adenocarcinoma in EPIC. Increased body fat explained only a small portion of the statistical association between UPF consumption and the risk of these upper respiratory and digestive tract cancers.
Fernanda Morales-Berstein, Wellcome Trust PhD student at the University of Bristol and lead author of the study, explains: “UPFs have been associated with obesity and increased body fat in several observational studies. This makes sense, because they are generally tasty, convenient and cheap and promote the consumption of large portions and an excessive number of calories. However, it was interesting that in our study the association between eating UPFs and upper respiratory and digestive tract cancer did not appear to be strongly explained by body mass index and waist-to-hip ratio.”
The authors suggest that other mechanisms may explain the association. For example, additives, including emulsifiers and artificial sweeteners that have previously been linked to disease risks, and contaminants from food packaging and the manufacturing process, may partially explain the link between UPF consumption and upper respiratory and digestive tract cancers in this study.
However, Fernanda Morales-Berstein and colleagues were cautious with their findings, suggesting that the associations between UPF consumption and upper respiratory and digestive tract cancers found in the study could be influenced by certain types of biases. This would explain why they found evidence of a link between higher UPF consumption and an increased risk of fatal accidents, which is highly unlikely to be causal.
George Davey Smith, professor of clinical epidemiology and director of the MRC Integrative Epidemiology Unit at the University of Bristol, and co-author of the paper, said: “UPFs are clearly associated with many adverse health effects, but whether they actually cause, whether underlying factors such as general health-related behavior and socio-economic position are responsible for this association is still unclear as the association with accidental deaths draws attention.”
Inge Huybrechts, team head of the Lifestyle Exposures and Interventions team at the IARC, added: “Cohorts with long-term follow-up dietary intake assessments, also taking into account contemporary consumption habits, are needed to validate the findings of this study to be replicated, as the EPIC dietary data had been collected in the 1990s, when UPF consumption was still relatively low. As such, the associations may potentially be stronger across cohorts including recent follow-up nutritional assessments.”
Further research is needed to identify other mechanisms, such as food additives and contaminants, that may explain the observed associations.
Based on the finding that body fat did not largely explain the link between UPF consumption and upper digestive tract cancer risk in this study, Fernanda Morales-Berstein suggested: “We are unlikely to focus solely on weight loss treatments, such as Semaglutide. to contribute greatly to the prevention of upper respiratory and digestive tract cancers associated with eating UPFs.”
Dr. Helen Croker, deputy director of research and policy at the World Cancer Research Fund, added: “This study adds to a growing body of evidence suggesting a link between UPFs and cancer risk. The link between higher consumption of UPFs and an increased risk of developing upper respiratory cancer supports our cancer prevention recommendations to eat a healthy diet rich in whole grains, vegetables, fruits and beans.”
The study was funded by the Wellcome Trust; Cancer Research UK; World Cancer Research Fund International; National Institute for Cancer; Horizon 2020 ‘Dynamic longitudinal exposome trajectories in cardiovascular and metabolic non-communicable diseases’ study; Fellowship of the Vice-Chancellor of the University of Bristol; British Heart Foundation and the Medical Research Council.
Paper
‘Ultra-processed foods, adipose tissue and risk of head and neck cancer and oesophageal adenocarcinoma in the European Prospective Investigation into Cancer and Nutrition study: a mediation analysis’ by F. Morales-Berstein et al. European Journal of Nutrition.
More information
About ultra-processed food
Ultra-processed foods (UPFs) are industrial formulations that are manufactured in a complex manner with ingredients not normally found in kitchens (e.g. maltodextrin, hydrogenated oils, modified starches) and cosmetic additives (e.g. emulsifiers, flavors, colorants, artificial sweeteners) . They are usually cheap, very tasty and widely available ready-made products. As a result, they often replace more nutritious, whole/minimally processed foods in the diet.