Highly processed foods linked to cancer
15th February 2018 – The growing popularity of highly processed foods may be storing up a future sharp rise in cancer cases, French researchers are warning.
A study in The BMJ suggests that a 10% increase in the proportion of 'ultra-processed' foods in the diet is linked to increases of 12% in the risk of overall cancer and 11% in the risk of breast cancer.
The authors call for further investigations to understand how the various characteristics of processing food may contribute towards cancer risk.
Crisps, snacks and ready meals
Ultra-processed foods include crisps, confectionery, mass-produced bread, ready meals, sugary cereals and fizzy drinks.
They usually contain sweeteners, emulsifiers, preservatives, colours and flavours, and may be high in fat and salt. They usually lack vitamins and minerals.
The popularity of ultra-processed foods has soared in recent decades because they are highly palatable, cheap and widely available.
Some surveys in Europe, the US and elsewhere have suggested that these foods contribute to between 25% and 50% of daily energy intake.
Food diaries and cancer cases
A research team led by Sorbonne Paris Cité University looked at food surveys for 104,980 healthy French adults – of whom 78% were women and 22% men – with an average age of 43.
They grouped foods according to how processed or unprocessed they were and compared the results to cases of cancer over an average of 5 years.
Although ultra-processed foods were linked to cancers in general, and breast cancer in particular, no association was found with prostate cancer or bowel cancer.
Further testing found no significant link between less processed foods, such as canned vegetables, cheeses and freshly made unpackaged bread and the risk of cancer.
Significantly, eating fresh or minimally processed foods, including fruit, vegetables, pulses, rice, pasta, eggs, meat, fish and milk was associated with lower risks of overall cancer and breast cancer, the researchers report.
The authors point out that the observational nature of the investigation means they cannot say for certain that these types of processed food definitely cause cancer.
Also, they are unable to say which part of the processing chain might be responsible for any increase in cancer risk. It could, for instance, be linked to nutritional composition, food additives or contact with packaging materials.
'Now we need to join the dots'
Carolyn Rogers, clinical nurse specialist at Breast Cancer Care, comments in an emailed statement: "Although this research is intriguing and will add to existing evidence on how diet may impact breast cancer risk, it’s far from conclusive.
"Now we need to connect the dots and find out if any specific elements in these foods may increase the risk of developing cancer."
Eluned Hughes, head of public health and information at Breast Cancer Now, says: "It is difficult to distinguish the specific effects of ultra-processed foods – or any particular food group – from those of other diet and lifestyle factors. This is because there might be several factors at play – for example, people who eat more processed foods might also be less physically active or have other risk factors.
"We look forward to further research to unravel the complex relationship between nutrition and breast cancer risk.
"What we do know is that limiting the amount of processed food you eat as part of a healthy balanced diet high in fruit, vegetables and pulses – as well as being physically active – can help you maintain a healthy weight, which has been scientifically proven to reduce the risk of developing breast cancer."