Ultra-processed foods linked to increased risk of cancers

It has long been known that diet impacts health, but a recent study revealed it may actually increase the likelihood of developing cancer. Cancer is a global problem, but the World Cancer Research Fund and American Institute for Cancer Research suggested that changing lifestyle and dietary habits could help prevent about a third of the most common neoplasms.

According to research published in the British Medical Journal, a 10% increase in the proportion of heavily processed foods in a person’s diet meant they were 12% more likely to develop all cancers and 11% more likely to develop breast cancer.

Nearly 105,000 participants from the NutriNet-Santé cohort were asked to fill out three surveys every six months which reported their 24-hour dietary intake. They were followed for an average of five years and each participant filled out a minimum of two surveys.

While none of the participants had cancer at the beginning of the study, the follow-up revealed that 2228 cancer cases had been diagnosed, of which 739 were breast cancers, 281 prostate cancers and 153 colorectal cancers.

Foods that were categorised as ultra-processed included mass-produced packaged breads and buns; packaged snacks; industrialised confectionery and desserts; sodas and sweetened drinks; reconstituted meat products such as fish nuggets; instant noodles and soups; and ready meals. Sugary products were the main contributor to ultra-processed food intake at 26%, followed by drinks (20%), starchy foods and breakfast cereals (16%), and ultra-processed fruits and vegetables (15%).

While fats and sauces, sugary products and drinks were associated with an increased risk of overall cancer, ultra-processed sugary products were associated with the risk of breast cancer.

Individuals who consumed the most ultra-processed foods tended to be younger, current smokers, less active and less educated. The researchers also found they had higher intakes of energy, lipids, carbohydrates and sodium.

Lead study author Bernard Srour of the French Institute of Health and Medical Research noted that the nutritional value of these products was not the only issue contributing to cancer risks.

“Ultra-processed foods and beverages contain some food additives for which carcinogenic effects are suspected such as titanium dioxide, a white food pigment which can be found in some confectioneries, chewing gums and biscuits,” he said. “Ultra-processed foods are also often packaged in plastic which might contain contact materials having controversial effects on health, such as bisphenol A (BPA).”

Previous studies have found a connection between ultra-processed foods and the increased risk of obesity and hypertension, but the researchers believe this was the first epidemiological study to evaluate the association between food processing and risk of cancer.

However, there were several limitations. The participants were predominantly female (78.3%) and they may not have been a true representation of the general French population; they were more health-conscious and had higher income and education levels.

Since some carcinogenic processes can take several decades, the long-term impact cannot be confirmed and further assessments on the effects of processing and food additives would be needed.

Furthermore, the study can prove an association exists between processed foods and cancer, but not a causal effect. The researchers emphasised that it is still important to limit the intake of processed foods.

“We know that some processed foods have a higher content of saturated fat, added sugars, salt and lower fibre,” said Martin Lajous, author of the accompanying study editorial, and a researcher at the National Institute of Public Health in Mexico City and the Harvard T.H. Chan School of Public Health. “This makes some processed foods unhealthy, so while we wait to know whether unprocessed foods are linked to cancer or not, patients should seek to increase their intake of healthy foods.”

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