Associations between degree of food processing and colorectal cancer risk in a large-scale European cohort

Industrial food processing has been linked to various health outcomes including cancer. To examine associations between the degree of food processing and risk of colorectal cancer (CRC) and its sub-sites, data from the European Prospective Investigation into Cancer (EPIC) including 6155 incident CRC cases (n = 450,111 participants), were analyzed. Dietary intakes were assessed using baseline food frequency questionnaires. Foods were classified into culinary ingredients, unprocessed, processed (PFs), and ultra-processed foods (UPFs) according to the Nova classification. Cox proportional hazards models, adjusted for established CRC risk factors, were used to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs) associated with a 10% increase in proportion of consumption (%g/d) of each Nova group. Substitution analysis examined the effect of replacing UPFs and PFs with unprocessed foods on CRC risk. A 10% increase in proportion of UPFs was associated with 6% higher CRC risk (95% CI:1.02-1.10). A positive association was also found between PFs and CRC risk (HR per 10% increase: 1.10 [95% CI, 1.05-1.15]). Conversely, unprocessed food consumption was inversely associated with CRC risk (HR per 10% increase: 0.93[95% CI, 0.90-0.95]). Substitution of 10% of the overall proportion of the diet comprising UPFs or PFs with 10% unprocessed foods was associated with a decreased risk of CRC (HR_UPFs: 0.94 [95% CI, 0.90-0.97]; HR_PFs: 0.90 [95% CI, 0.86-0.94]). In conclusion, UPF was positively associated with CRC risk while diets richer in unprocessed foods were associated with lower CRC risk. Further studies are needed to understand the mechanisms by which food processing affects CRC risk.