Ultra-processed foods linked to higher risk of some cancers

A large study has found a link between higher consumption of ultra-processed foods and the risk of developing head, neck, and esophageal cancers. However, they found that obesity, often caused by eating too much of these foods, was not a large contributing factor. The findings highlight the need to examine factors other than body fat to explain this association.

Ultra-processed foods (UPFs) tend to be energy-dense but low in nutrients. They usually include additives and ingredients not typically used in home cooking, such as preservatives, emulsifiers, sweeteners, and artificial colors and flavors. Examples include ice cream, ham, sausages, confectionery, breakfast cereals, biscuits, and carbonated drinks. UFP consumption has been associated with an increased risk of obesity.

A new study led by the University of Bristol has examined the association between UFP consumption and the risk of developing head, neck and esophageal cancer and whether obesity was a contributing factor.

“UPFs have been associated with excess weight and increased body fat in several observational studies,” said Fernanda Morales-Bernstein, lead and corresponding author of the study. “This makes sense, as they are generally tasty, convenient and cheap, favoring the consumption of large portions and an excessive number of calories. However, it was interesting that in our study the link between eating UFPs and upper-aerodigestive tract cancer didn’t seem to be greatly explained by body mass index and waist-to-hip ratio.”

A study published earlier this year found a positive association between higher consumption of UPFs and the risk of head and neck cancer and esophageal adenocarcinoma, a cancer that starts in the mucus-secreting glands of the esophagus. The researchers in the current study wanted to explore these findings further.

They included 450,111 participants who’d been involved in the previous study, the European Prospective Investigation into Cancer and Nutrition (EPIC). Participants in that study had been recruited from 10 European countries and were followed for almost 14 years; most were 35 to 69 years old at recruitment, and 70.8% were female.

The UFPs consumed by participants were mainly composed of carbonated drinks, non-carbonated sweetened drinks, ultra-processed dairy products, ultra-processed breads, and ultra-processed meats. Over the course of the study, there were 910 incident cases of head and neck cancer and 215 of esophageal adenocarcinoma.

Analysis showed that eating 10% more UPFs was associated with a 23% higher risk of head and neck cancer and a 24% higher risk of esophageal adenocarcinoma. Increased body fat only explained a small proportion of the statistical association between UPF consumption and the risk of these so-called upper-aerodigestive tract cancers.

The researchers suggest, based on their findings in relation to increased body fat, that other mechanisms are likely involved. For example, the addition of emulsifiers and artificial sweeteners, which have been associated with increased disease risk, and contaminants from food packaging and the manufacturing process.

The researchers caution that their findings might be affected by certain types of bias. Most notably, they found a strange association between increased UPF consumption and a higher risk of accidental death.

“UPFs are clearly associated with many adverse health outcomes, yet whether they actually cause these, or whether underlying factors such as general health-related behaviors and socioeconomic position are responsible for the link, is still unclear, as the association with accidental deaths draws attention to,” said George Davey Smith, one of the study’s co-authors.

However, based on the finding that body fat did not greatly explain the association between UPFs and cancer, the researchers suggest moving the focus away from overweight or obesity.

“Focusing solely on weight loss treatment, such as semaglutide, is unlikely to greatly contribute to the prevention of upper-aerodigestive tract cancers related to eating UFPs,” Morales-Bernstein said.

Further research is needed to identify mechanisms other than body fat that might contribute to the cancer risk identified in the study and to replicate its findings, given the age of the EPIC study.

“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,” said Inge Huybrechts, another co-author. “As such association may potentially be stronger in cohorts including recent dietary follow-up assessments.”

The study was published in the European Journal of Nutrition.

Source: University of Bristol

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