Ultra-processed foods and higher risk of mouth, throat and esophagus cancers

Eating more ultra-processed foods (UPFs) may be associated with a higher risk of developing cancers of upper aerodigestive tract (including the mouth, throat and esophagus), according to a new study led by researchers from the University of Bristol and the International Agency for Research on Cancer (IARC). The authors of this international study, which analysed diet and lifestyle data on 450,111 adults who were followed for approximately 14 years, sayobesity associated with the consumption of UPFs may not be the only factor to blame. The study is published today [22 November] in the European Journal of Nutrition.

Several studies have identified an association between UPF consumption and cancer, including a recent study which looked at the association 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 the Bristol Medical School and IARC wanted to explore this further.

Since many UPFs have an unhealthy nutritional profile, the team sought to establish 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 analyses 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 only explained a small proportion of the statistical association between UPF consumption and the risk of these upper-aerodigestive tract cancers.

Fernanda Morales-Berstein, a Wellcome Trust PhD student at the University of Bristol and the study's lead author, explained: "UPFs have been associated with excess weight and increased body fat in several observational studies. This makes sense, as they are generally tasty, convenient and cheap, favouring the consumption of large portions and an excessive number of calories. However, it was interesting that in our study the link between eating UPFs and upper-aerodigestive tract cancer didn't seem to be greatly explained by body mass index and waist-to-hip ratio."

The authors suggest that other mechanisms could explain the association.

For example, additives including emulsifiers and artificial sweeteners which have been previously associated with disease risk, and contaminants from food packaging and the manufacturing process, may partly explain the link between UPF consumption and upper-aerodigestive tract cancer in this study.

However, Fernanda Morales-Berstein and colleagues did add caution regarding their findings and suggest that the associations between UPF consumption and upper-aerodigestive tract cancers found in the study could be affected by certain types of bias.

This would explain why they found evidence of an association between higher UPF consumption and increased risk of accidental deaths, 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 on the paper, said: "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 socioeconomic position are responsible for the link, is still unclear, as the association with accidental deaths draws attention to."

Inge Huybrechts, Team head of the Lifestyle exposures and interventions team at IARC, added: "Cohorts with long-term dietary follow-up intake assessments, considering also contemporary consumption habits, are needed to replicate these study's findings, as the EPIC dietary data were collected in the 1990s, when the consumption of UPFs was still relatively low. As such associations may potentially be stronger in cohorts including recent dietary follow-up assessments."

Further research is needed to identify other mechanisms, such as food additives and contaminants, which may explain the links observed.

However, based on the finding that body fat did not greatly explain the link between UPF consumption and upper-aerodigestive tract cancer risk in this study, Fernanda Morales-Berstein, suggested: "Focussing solely on weight loss treatment, such as Semaglutide, is unlikely to greatly contribute to the prevention of upper-aerodigestive tract cancers related to eating UPFs."

Dr Helen Croker, Assistant Director of Research and Policy at World Cancer Research Fund, added: "This study adds to a growing pool of evidence suggesting a link between UPFs and cancer risk. The association between a higher consumption of UPFs and an increased risk of developing upper-aerodigestive tract cancer supports our Cancer Prevention Recommendations to eat a healthy diet, rich in wholegrains, vegetables, fruit, and beans."

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Ultra-processed foods may be linked to increased risk of cancer

Higher consumption of ultra-processed foods may be linked to an increased risk of developing and dying from cancer, an Imperial College London-led observational study suggests.

Researchers from Imperial’s School of Public Health have produced the most comprehensive assessment to date of the association between ultra-processed foods and the risk of developing cancers. Ultra-processed foods are food items which have been heavily processed during their production, such as fizzy drinks, mass-produced packaged breads, many ready meals and most breakfast cereals.

Ultra-processed foods are often relatively cheap, convenient, and heavily marketed, often as healthy options. But these foods are also generally higher in salt, fat, sugar, and contain artificial additives. It is now well documented that they are linked with a range of poor health outcomes including obesity, type 2 diabetes and cardiovascular disease.

The first UK study of its kind used UK Biobank records to collect information on the diets of 200,000 middle-aged adult participants. Researchers monitored participants’ health over a 10-year period, looking at the risk of developing any cancer overall as well as the specific risk of developing 34 types of cancer. They also looked at the risk of people dying from cancer.

The study found that higher consumption of ultra-processed foods was associated with a greater risk of developing cancer overall, and specifically with ovarian and brain cancers. It was also associated with an increased risk of dying from cancer, most notably with ovarian and breast cancers.

For every 10 per cent increase in ultra-processed food in a person’s diet, there was an increased incidence of 2 per cent for cancer overall, and a 19 per cent increase for ovarian cancer specifically.

Each 10 per cent increase in ultra-processed food consumption was also associated with increased mortality for cancer overall by 6 per cent, alongside a 16 per cent increase for breast cancer and a 30 per cent increase for ovarian cancer.

These links remained after adjusting for a range of socio-economic, behavioural and dietary factors, such as smoking status, physical activity and body mass index (BMI).

The Imperial team carried out the study, which is published in eClinicalMedicine, in collaboration with researchers from the International Agency for Research on Cancer (IARC), University of São Paulo, and NOVA University Lisbon.

Previous research from the team reported the levels of consumption of ultra-processed foods in the UK, which are the highest in Europe for both adults and children. The team also found that higher consumption of ultra-processed foods was associated with a greater risk of developing obesity and type 2 diabetes in UK adults, and a greater weight gain in UK children extending from childhood to young adulthood.

Dr Eszter Vamos, lead senior author for the study, from Imperial College London’s School of Public Health, said: “This study adds to the growing evidence that ultra-processed foods are likely to negatively impact our health including our risk for cancer. Given the high levels of consumption in UK adults and children, this has important implications for future health outcomes.

“Although our study cannot prove causation, other available evidence shows that reducing ultra-processed foods in our diet could provide important health benefits. Further research is needed to confirm these findings and understand the best public health strategies to reduce the widespread presence and harms of ultra-processed foods in our diet.”

Dr Kiara Chang, first author for the study, from Imperial College London’s School of Public Health, said: “The average person in the UK consumes more than half of their daily energy intake from ultra-processed foods. This is exceptionally high and concerning as ultra-processed foods are produced with industrially derived ingredients and often use food additives to adjust colour, flavour, consistency, texture, or extend shelf life.

“Our bodies may not react the same way to these ultra-processed ingredients and additives as they do to fresh and nutritious minimally processed foods. However, ultra-processed foods are everywhere and highly marketed with cheap price and attractive packaging to promote consumption. This shows our food environment needs urgent reform to protect the population from ultra-processed foods.”

The World Health Organisation and the United Nations’ Food and Agriculture Organisation has previously recommended restricting ultra-processed foods as part of a healthy sustainable diet.

There are ongoing efforts to reduce ultra-processed food consumption around the world, with countries such as Brazil, France and Canada updating their national dietary guidelines with recommendations to limit such foods. Brazil has also banned the marketing of ultra-processed foods in schools. There are currently no similar measures to tackle ultra-processed foods in the UK.

Dr Chang added: “We need clear front of pack warning labels for ultra-processed foods to aid consumer choices, and our sugar tax should be extended to cover ultra-processed fizzy drinks, fruit-based and milk-based drinks, as well as other ultra-processed products.

“Lower income households are particularly vulnerable to these cheap and unhealthy ultra-processed foods. Minimally processed and freshly prepared meals should be subsidised to ensure everyone has access to healthy, nutritious and affordable options.”

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