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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Predatory dinosaurs such as T. rex sported lizard-like lips

A new study suggests that predatory dinosaurs, such as Tyrannosaurus rex, did not have permanently exposed teeth as depicted in films such as Jurassic Park, but instead had scaly, lizard-like lips covering and sealing their mouths.

Researchers and artists have debated whether theropod dinosaurs, the group of two-legged dinosaurs that includes carnivores and top predators like T. rex and Velociraptor, as well as birds, had lipless mouths where perpetually visible upper teeth hung over their lower jaws, similar to the mouth of a crocodile.

However, an international team of researchers challenge some of the best-known depictions, and say these dinosaurs had lips similar to those of lizards and their relative, the tuatara -- a rare reptile found only in New Zealand, which are the last survivors of an order of reptiles that thrived in the age of the dinosaurs.

In the most detailed study of this issue yet, the researchers examined the tooth structure, wear patterns and jaw morphology of lipped and lipless reptile groups and found that theropod mouth anatomy and functionality resembles that of lizards more than crocodiles. This implies lizard-like oral tissues, including scaly lips covering their teeth.

These lips were probably not muscular, like they are in mammals. Most reptile lips cover their teeth but cannot be moved independently -- they cannot be curled back into a snarl, or make other sorts of movements we associate with lips in humans or other mammals.

Study co-author Derek Larson, Collections Manager and Researcher in Palaeontology at the Royal BC Museum in Canada, said: "Palaeontologists often like to compare extinct animals to their closest living relatives, but in the case of dinosaurs, their closest relatives have been evolutionarily distinct for hundreds of millions of years and today are incredibly specialised.

"It's quite remarkable how similar theropod teeth are to monitor lizards. From the smallest dwarf monitor to the Komodo dragon, the teeth function in much the same way. So, monitors can be compared quite favourably with extinct animals like theropod dinosaurs based on this similarity of function, even though they are not closely related."

Co-author Dr Mark Witton from the University of Portsmouth said: "Dinosaur artists have gone back and forth on lips since we started restoring dinosaurs during the 19th century, but lipless dinosaurs became more prominent in the 1980s and 1990s. They were then deeply rooted in popular culture through films and documentaries -- Jurassic Park and its sequels, Walking with Dinosaurs and so on.

"Curiously, there was never a dedicated study or discovery instigating this change and, to a large extent, it probably reflected preference for a new, ferocious-looking aesthetic rather than a shift in scientific thinking. We're upending this popular depiction by covering their teeth with lizard-like lips. This means a lot of our favourite dinosaur depictions are incorrect, including the iconic Jurassic Park T. rex."

The results, published in the journal Science, found that tooth wear in lipless animals was markedly different from that seen in carnivorous dinosaurs and that dinosaur teeth were no larger, relative to skull size, than those of modern lizards, implying they were not too big to cover with lips.

Also, the distribution of small holes around the jaws, which supply nerves and blood to the gums and tissues around the mouth, were more lizard-like in dinosaurs than crocodile-like. Furthermore, modelling mouth closure of lipless theropod jaws showed that the lower jaw either had to crush jaw-supporting bones or disarticulate the jaw joint to seal the mouth.

"As any dentist will tell you, saliva is important for maintaining the health of your teeth. Teeth that are not covered by lips risk drying out and can be subject to more damage during feeding or fighting, as we see in crocodiles, but not in dinosaurs," said co-author Kirstin Brink, Assistant Professor of Palaeontology at the University of Manitoba.

She added: "Dinosaur teeth have very thin enamel and mammal teeth have thick enamel (with some exceptions). Crocodile enamel is a bit thicker than dinosaur enamel, but not as thick as mammalian enamel. There are some mammal groups that do have exposed enamel, but their enamel is modified to withstand exposure."

Thomas Cullen, Assistant Professor of Paleobiology at Auburn University and study lead author, said: "Although it's been argued in the past that the teeth of predatory dinosaurs might be too big to be covered by lips, our study shows that, in actuality, their teeth were not atypically large. Even the giant teeth of tyrannosaurs are proportionally similar in size to those of living predatory lizards when compared for skull size, rejecting the idea that their teeth were too big to cover with lips."

The results provide new insights into how we reconstruct the soft-tissues and appearance of dinosaurs and other extinct species. This can give crucial information on how they fed, how they maintained their dental health, and the broader patterns of their evolution and ecology.

Dr Witton said: "Some take the view that we're clueless about the appearance of dinosaurs beyond basic features like the number of fingers and toes. But our study, and others like it, show that we have an increasingly good handle on many aspects of dinosaur appearance. Far from being clueless, we're now at a point where we can say 'oh, that doesn't have lips? Or a certain type of scale or feather?' Then that's as realistic a depiction of that species as a tiger without stripes."

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Why chocolate feels so good -- it is all down to lubrication

Scientists have decoded the physical process that takes place in the mouth when a piece of chocolate is eaten, as it changes from a solid into a smooth emulsion that many people find totally irresistible.

By analysing each of the steps, the interdisciplinary research team at the University of Leeds hope it will lead to the development of a new generation of luxury chocolates that will have the same feel and texture but will be healthier to consume.

During the moments it is in the mouth, the chocolate sensation arises from the way the chocolate is lubricated, either from ingredients in the chocolate itself or from saliva or a combination of the two.

Fat plays a key function almost immediately when a piece of chocolate is in contact with the tongue. After that, solid cocoa particles are released and they become important in terms of the tactile sensation, so fat deeper inside the chocolate plays a rather limited role and could be reduced without having an impact on the feel or sensation of chocolate.

Anwesha Sarkar, Professor of Colloids and Surfaces in the School of Food Science and Nutrition at Leeds, said: "Lubrication science gives mechanistic insights into how food actually feels in the mouth. You can use that knowledge to design food with better taste, texture or health benefits.

"If a chocolate has 5% fat or 50% fat it will still form droplets in the mouth and that gives you the chocolate sensation. However, it is the location of the fat in the make-up of the chocolate which matters in each stage of lubrication, and that has been rarely researched.

"We are showing that the fat layer needs to be on the outer layer of the chocolate, this matters the most, followed by effective coating of the cocoa particles by fat, these help to make chocolate feel so good."

The study -- published in the scientific journal ACS Applied Materials and Interface -- did not investigate the question of how chocolate tastes. Instead, the investigation focused on its feel and texture.

Tests were conducted using a luxury brand of dark chocolate on an artificial 3D tongue-like surface that was designed at the University of Leeds. The researchers used analytical techniques from a field of engineering called tribology to conduct the study, which included in situ imaging.

Tribology is about how surfaces and fluids interact, the levels of friction between them and the role of lubrication: in this case, saliva or liquids from the chocolate. Those mechanisms are all happening in the mouth when chocolate is eaten.

When chocolate is in contact with the tongue, it releases a fatty film that coats the tongue and other surfaces in the mouth. It is this fatty film that makes the chocolate feel smooth throughout the entire time it is in the mouth.

Dr Siavash Soltanahmadi, from the School of Food Science and Nutrition at Leeds and the lead researcher in the study, said: "With the understanding of the physical mechanisms that happen as people eat chocolate, we believe that a next generation of chocolate can be developed that offers the feel and sensation of high-fat chocolate yet is a healthier choice.

"Our research opens the possibility that manufacturers can intelligently design dark chocolate to reduce the overall fat content.

"We believe dark chocolate can be produced in a gradient-layered architecture with fat covering the surface of chocolates and particles to offer the sought after self-indulging experience without adding too much fat inside the body of the chocolate."

Revenue from chocolate sales in the UK is forecast to grow over the next five years, according to research from the business intelligence agency MINTEL. Sales are expected to grow 13% between 2022 and 2027 to reach £6.6 billion.

The researchers believe the physical techniques used in the study could be applied to the investigation of other foodstuffs that undergo a phase change, where a substance is transformed from a solid to a liquid, such as ice-cream, margarine or cheese.

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