High intake of Ultra-Processed Foods and risk of Colorectal Cancer: The Norwegian Women and Cancer study

Abstract

Background: Norway is one of the countries with the highest rate of colorectal cancer (CRC). Previous research on diet and CRC has been heavily based on nutrients and foods, but new findings indicate that the way we process food may be of importance. However, the findings are contradictory. Further, new findings indicate that CRC risk factors might affect colorectal subsites differently. As the modern diet is changing towards including more ultra-processed food (UPF), a better understanding of how food processing affects CRC might be a new approach to prevent CRC. This raises the question: is there an association between high intake of UPF and CRC risk?

Method: 77,100 women (1625 cases) from the Norwegian Women and Cancer study were included in this prospective cohort analysis. Dietary intakes were collected using validated semi-quantitative food frequency questionnaires. The foods were categorized based on the degree they had been processed by using the NOVA classification system. Multivariable Cox proportional hazard models were used to assess the association between high intake of UPF and CRC risk.

Results: A high UPF intake, compared to a low UPF intake, was not significantly significant associated with increased total CRC risk after adjusting for all covariates, including energy intake(HR=1.21; 95% CI 1.01-1.46, P-trend = 0.08). However, a high UPF intake, compared to a low UPF intake, was statistically significant associated with right-sided colon cancer when adjusting for covariates(HR=1.28; 95% CI 1.03-1.60, P-trend = 0.04). The average follow-up time was 17.4 years.

Conclusions: Results in this large prospective cohort suggest no overall association between a high UPF intake and risk of CRC. However, an association between a high UPF intake and right-sided colon cancer was found. These findings indicate that UPF affects colorectal subsites differently. Further research investigating the association between UPF and CRC is needed to determine causality.