Ultra processed foods and cancer: foods that may be slowly killing you

Do you like to buy processed foods because they're easy to prepare in a rush? Or because your kids love them? Be warned: there might be a link between ultra processed foods and cancer.

The latest research on the subject suggests that there’s a link between cancer and “ultra-processed” foods such as cookies, fizzy drinks, and sugary cereals. However, other experts cautioned everybody from jumping to conclusions outside the study’s scope.

The group from the Université Sorbonne-Paris-Cité  was composed of researchers from France and Brazil. They looked into data collected from 105,000 French adults. The participants completed online questionnaires that inquired about their intake of 3,300 different food items. The researchers followed the participants for an average of five years. Middle-aged women comprised most of the participants.

Processed foods and cancer

The results showed that if the proportion of ultra-processed food in the diet increased by 10%, then the number of cancers detected increased by 12%. The researchers then compared these results to diagnosed cancer cases within the group.

The British Medical Journal, a weekly peer-reviewed medical journal which published the research, released a statement about the study.

"The results show that a 10% increase in the proportion of ultra-processed foods in the diet was associated with increases of 12% in the risk of overall cancer, and 11% in the risk of breast cancer."

However, they did not find any significant association between these foods and prostate or colorectal cancer.

Kinds of processed foods

The list of ultra-processed foods included the following:

• Mass-produced packaged breads and buns
• Sweet or savoury packaged snacks including crisps/chips
• Chocolate bars and sweets
• Sodas and sweetened drinks
• Meatballs, poultry and fish nuggets
• Instant noodles and soups
• Frozen or shelf-life ready meals
• Food made mostly or entirely from sugar, oils and fats

The study also reveals the following findings:

• An average of 18% of people's diet was “ultra-processed”
• Each year, there are 79 cancers per 10,000 people on average
• Raising the intake of processed food by 10% would add nine extra cancers per 10,000 people per year

"These results suggest that the rapidly increasing consumption of ultra-processed foods may drive an increasing burden of cancer in the next decades,” the researchers’ conclusion said.

Link between processed foods and cancer still needs work

But they said the findings need to "be confirmed by other large-scale" studies. They also admit that other scientists need to do more research to establish what could be behind the link.

Previous studies have already shown that there’s a link between processed foods (high in sugar, fat, and salt) to obesity, high blood pressure, and high cholesterol. However, firm evidence for increased disease risk has been, the research team says, “scarce.”

The research team further stressed that their study merely showed a correlation between cancer and an ultra-processed-food diet. They cautioned that this link could be coincidental, and does not give conclusive proof that this type of food actively causes cancer.

They added that their findings need to "be confirmed by other large-scale" studies, and further research is needed to strengthen the link.

Weak associations between processed foods and cancer

Dr. Ian Johnson, a nutrition researcher from the Quadram Institute Bioscience in England, weighed in about the research. He said the research authors identified "some rather weak associations, of low statistical significance."

"The problem is that the definition of ultra-processed foods they have used is so broad and poorly defined that it is impossible to decide exactly what, if any, causal connections have been observed," he said in comments at the Science Media Centre.

Professor Tom Sanders, Head of Diabetes & Nutritional Sciences Division at King’s College London, agreed. He said the term "ultra-processed food" was "difficult to define."

"The definition excludes many home-made or artisanal foods such as bread, cakes, biscuits, butter, meat, cheese, tinned fruit and vegetables as well as sugar and salt used in domestic food preparation," he said.

He explained in one example how mass-produced bread is classified as ultra-processed, but a home-made loaf of bread from a posh local bakery would not.

"From a nutritional standpoint, this classification seems arbitrary and based on the premise that food produced industrially has a different nutritional and chemical composition from that produced in the home or by artisans. This is not the case."

Other factors in processed foods and cancer debate

Apart from the definition of the term “ultra-processed food,” there are factors that contribute to cancer that the study didn't fully take into account. For example, some participants may practice behaviours that have links to cancer. Some of them smoke, do not get enough exercise, and consume more calories overall.

"It's already known that eating a lot of these foods can lead to weight gain, and being overweight or obese can also increase your risk of cancer, so it's hard to disentangle the effects of diet and weight," said Professor Linda Bauld, Cancer Research UK's prevention expert.

In spite of the shortcomings of the study, she said it was a "warning signal to us to have a healthy diet."

Mums and dads, what you should remember is that it's okay if your child eats fast food occasionally. As long as they’re eating a well-balanced diet containing plenty of fruits, vegetables, and fibre, they’ll be fine.

Sources: BBC, Channel News Asia

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