In recent decades, ultra-processed foods have become an increasing part of the diet. A growing number of studies are pointing out the harmful effects of these products. On World Health Day, Aprifel looks back at a recent study conducted by the International Agency for Research on Cancer. This study is the largest epidemiological study to date on the influence of ultra-processed food consumption on the risk of cancer, and confirms the link already identified by previous studies. From a public health perspective, this study provides arguments for recommending a reduction in the consumption of ultra-processed foods in favour of unprocessed or minimally processed foods.
Ultra-processed foods are characterized by high energy density and lower nutritional quality. They can account for 25% to 60% of average total energy intake in high- and middle-income countries (Cediel et al, 2021; da Costa Louzada et al, 2018). This situation is concerning because multiple works suggest that the consumption of ultra-processed products is associated with overweight, obesity, and non-communicable diseases. Their consumption has also been associated with specific cancers such as breast cancer and colorectal cancer (Fiolet et al, 2018 ; Romaguera et al, 2021). However, data from epidemiological studies on this association are still lacking.
To expand on this knowledge, a recent study conducted by the IARC, and based on the EPIC study examined the association between the degree of food processing and cancer risk. This study is the largest prospective cohort to examine this association. Its results confirm the link already identified by previous studies between consumption of ultra-processed foods and increased risk of cancers.
Ultra-processed foods account for 32% of average total energy intake
A total of nearly 450,000 individuals from 9 European countries were included in this study. Their dietary intake was analysed according to food processing level using the NOVA classification system (see box). The contribution of ultra-processed foods to the daily diet was then determined in terms of quantity and energy.
Overall, for the entire cohort, unprocessed or minimally processed foods contribute to 35.9% of total energy intake, with France at the top of the highest consumers of these products. Culinary ingredients and processed foods account for 7.3% and 24.6% of total energy intake, respectively. Finally, ultra-processed foods contribute to 32% of total energy intake, Norway being the country with the highest level of consumption.
When compared to people who consume little ultra-processed food, those who consume the most are statistically:
- More likely to be physically active,
- More likely to have a diet high in energy, salt, fat and carbohydrates which deviates from the Mediterranean diet,
- Less likely to have a higher education level.
A 10% substitution of ultra-processed foods with an equal amount of healthier foods could reduce cancer risk
According to this work, high consumption of unprocessed and minimally processed foods is associated with a significant decrease in the risk of overall cancer and several types of site-specific cancers (head, neck, oesophagus, colon, rectum and liver). Conversely, high consumption of processed and ultra-processed foods is associated with an increased risk of cancers (all sites combined and site-specific analysis).
Based on these findings, researchers assessed the potential effect on cancer risk of replacing 10% of ultra-processed foods with an equal amount of minimally processed foods.
According to this model, replacing 10% of the ultra-processed foods consumed by unprocessed, healthier foods such as fruits, vegetables, cereals or milk would reduce the risk of several types of cancers (colon, liver and breast in postmenopausal women).
Thus, this work highlights the importance of food quality for cancer prevention as outlined in reports from the World Cancer Research Fund and the American Institute of Cancer Research. More broadly, these results support the implementation of public health recommendations encouraging the reduction of processed and ultra-processed foods and their replacement by unprocessed and minimally processed foods for the prevention of non-communicable diseases.
The NOVA classification is a classification tool created in 2010 by Brazilian epidemiologists with the aim of dividing foods into 4 groups according to their level of processing, ranging from unprocessed or minimally processed foods to ultra-processed foods.
- NOVA 1 – Unprocessed or minimally processed foods: fruit and vegetables, cereals, flour, pasta, meat, milk…
- NOVA 2 – Culinary ingredients with little processing: fats, sugar, salt…
- NOVA 3 – Processed foods (from group 1 and 2 commodities): bread, cheese, canned fruit and vegetables, smoked meats/fish…
- NOVA 4 – Ultra-processed foods (products from the previous groups with additives or other chemical substances): processed meat, sweetened beverages, industrial breads and pastries, sweetened products, chocolate…