- Latest research highlights a rise in cancer linked to an increased consumption of what are called ultra-processed foods.
For many of us, ‘ultra-processed foods’ are those foods we consider to be manufactured on an industrial scale in processing plants producing ready meals, chicken nuggets (which seems to be a popular item in most papers), manufactured bread, pot noodles and so on. To be perfectly honest, these are all foods in Group 4 of what is known as the NOVA classification. There are three other groups which include fresh and minimally processed foods, processed ingredients and processed foods. They are defined as you can probably guess from the degree of processing. The UPFs are all those that have undergone the most processing. These tend to be ‘industrialised’ formulations although this term requires further clarification.
The ultra-processed food group is also characterised by containing a list of added ingredients such as colours, fats, flavours, fibre, vitamins, minerals and salt, additives and so on.
From a demographic perspective, the consumption of ultra-processed food and drinks has gone up because of changes in people’s lifestyles. It would be covered by changes in economic prosperity, in industrial activity and alterations in the social fabric.
The total energy intake of European diets and other high- to middle-income countries from ultra-processed food is between 25 per cent and 50 per cent. It’s estimated UPFs account for half the food eaten in UK and US homes by virtually everyone.
A greater list can be generated but good examples are:
- Ready meals including all frozen foods and those with ambient shelf-lives
- Foods made with mostly sugar, carbohydrates, fats, oils, proteins
- Soft drinks, sodas and sweetened drinks
- Meatballs, poultry and fish nuggets including fishfingers
- Bread and buns which should also include home-made bread given the types of ingredients used.
- Industrialised baked goods like cakes and pies.
- Chocolate and snack bars
- Instant noodles and packaged soups
At the moment the NOVA classification is highly controversial because group 4 products would also include fortified foods such as cereals that contain folate, medical foods and baby foods which are clearly important in human health. However, there is a growing movement that would like to remove ultra-processed food ‘in toto’ from the grocery shelves.
In the last few years, there has been renewed focus on the role of ultra-processed foods in nutrition as they are called and their impact on human health. The types of diseases considered are type 2 diabetes, cardiovascular disease and raised levels of undefined premature death. One of the reasons for this controversial story on adverse human health is possibly because of over-consumption and easy consumption of such foods. It is however already established that processed meats in particular have been strongly associated with an increased risk of cancer. There is no association yet between all ultra-processed foods and drinks generally and an increased risk of cancer.
Ultra-Processed Food And Cancer
There have been a few studies that have looked at processed foods and its association with a variety of disease states including cancer. A Canadian study identified an increased risk of developing prostate cancer with a higher intake of processed foods. There was no link though with ultra-processed foods.
In a particular study that examined the prevalence of cancer generally and consumption of ultra-processed food, researchers at the Sorbonne in Paris, France examined the medical records and eating habits of 105,000 adults taking part in a large study. This was the French NutriNet-Santé cohort study.
The study mostly involved middle-aged women completing a food survey over two days to find out what they were eating. Participants recorded their intake of 3,300 different food items.
The main elements to be gleaned from the article were:-
Roughly, 18 per cent of a diet consumed by those surveyed contained ultra-processed food.
There were 70 cancers per 10,000 people each year.
If the proportion of processed food rose by 10 per cent, then nine extra cancers occurred per 10,000 people each year.
Based on comparative statistics, a 10 per cent increase in the amount of ultra-processed foods in the diet was linked to a 12% increase in cancers of various kind.
Breast cancer was one significant type picked up on. There was a 11 per cent increase here. There was no significant increase in prostate (only in those from the male population) or colorectal cancer.
The comment in the paper which has created most waves is this:-
“If confirmed in other populations and settings, these results suggest that the rapidly increasing consumption of ultra-processed foods may drive an increasing burden of cancer in the next decades.”
The issue for many when reading the comments section is what is defined as an ultra-processed food and why should all manufactured foods be classed as ultra-processed given that many home recipes involve some extreme processing. There is for example little consideration of consumption of red meat as far as can be ascertained in the paper.
Considerable caution is being expressed by many about the findings because there are so many other factors involved in cancer. The World Health Organisation (WHO) regards obesity as the biggest cause of the disease after smoking. Consuming processed meat is an issue but not as big as these two just referenced. A lot of behaviours which are associated with cancer are also linked in those who have particular diets. Some adjustments were made in the paper for other factors but they can never be entirely ruled out because they have confounding effects on their links to cancer.
The researchers are considering this an initial study which needs further assessment.
Colorectal Cancer And Ultra-Processed Foods
In 2021 it was reported from a large study by the Barcelona Institute for Global Health (ISGlobal), a center supported by the “la Caixa” Foundation, that consumption of UPF could increase the risk of developing colorectal cancer (Romaguera et al., (2021).
The study was based on findings from questionnaires concerning food behaviour of about 8,000 people in Spain. The study also looked at drink products as well. Three cancers were investigated, prostate, breast and colorectal cancer.
No association was seen with prostate cancer.
A higher risk of breast cancer was noted in a particular sub-group of previous and current smokers when they reported a diet full of ultra-processed foods.
The particular study details were a case-controlled study of 7,843 adults living in different Spanish provinces. Half the number of the participants already had cancer. These particular subjects already had a diagnosis of colorectal (1,852), breast (1,486) or prostate cancer (953). The remainder were those who did not have cancer but had similar characteristics.
Data was collected on dietary habits from the multi-case-control study MCC-Spain. Dietary data was collected using a validated questionnaire designed to examine and assess the frequency of consumption of usual food and drink items over a one-year period. The results were then classified according to the level of processing using the NOVA classification.
The association between UPF and increased risk of colorectal cancer was based on the finding that a 10 per cent increment in consumption of UPF was associated with a 11 per cent increase in the development of colorectal cancer.
The reason for this particular association was possibly because those who consumed UPFs were not consuming as much fruit and vegetables, and fibre as they should. These are all foods that are strongly linked to reducing the risk of developing colorectal cancer in particular. There was a claim that consumers of UFPs were also more susceptible because of the higher levels of consumption of additives with carcinogenic potential but given the types of additives now used as food ingredients, this becomes a highly tenuous association.
It’s worth noting that the authors contend “that food and public health policies and the IARC should already be taking food processing into account and discouraging the consumption of ultra-processed products.”
BMJ (2018) Consumption of ultra-processed foods and cancer risk: results from NutriNet-Santé prospective cohort. 360:k322 http://www.bmj.com/content/360/bmj.k322
Romaguera, D., et al. (2021) Consumption of ultra-processed foods and drinks and colorectal, breast, and prostate cancer. Clinical Nutrition. doi.org/10.1016/j.clnu.2021.02.033.
Originally published on 20/02/2018. Revised 02/06/2021 to include the findings of the new study from Romaguero et al., (2021) and improve the notes about Group 4 types of food.