TOPLINE:

A prospective cohort study found that a high intake of ultraprocessed foods (UPFs) was associated with an increased risk for overall colorectal cancer (CRC) and right-sided colon cancer.

METHODOLOGY:

• Researchers analysed data of 77,100 women (age, 30-70 years) from the Norwegian Women and Cancer Study, with 1625 cases of CRC identified during follow-up (mean time, 17.4 years) until December 2018.
• Dietary data were collected using validated semiquantitative food frequency questionnaires to assess participants' typical food intake over the previous year; the foods reported were classified using the NOVA classification system according to their level of processing.
• Quartiles of UPF intake were defined as low intake (≤ 274 g/d), medium-low intake (275-361 g/d), medium-high intake (362-465 g/d), and high intake (> 466 g/d).
• Researchers assessed the association between the amount of UPFs in the diet and the incidence of CRC on the total colorectum and its subsites.
• Covariates included age, smoking status, physical activity score, educational level, and menopausal hormone therapy use; the total energy intake was included as a confounding factor.

TAKEAWAY:

• After adjusting for covariates and energy intake, a high intake of UPFs was significantly associated with an increased risk for total CRC (hazard ratio [HR], 1.24; P for trend = .02) and colon cancer when stratified by subsites of the colorectal tract separately (HR, 1.31; P for trend = .02).
• A high intake of UPFs was strongly associated with an increased risk for right-sided colon cancer (HR, 1.58; P for trend < .001); however, no significant associations were found between a high intake of UPFs and left-sided colon or rectal cancer.
• Among women with a high BMI (≥ 25), a high intake of UPFs was significantly associated with the risk for CRC (HR, 1.33; P for trend = .04); those with a low intake of processed meat (< 30 g/d) showed similar associations (HR, 1.39; P for trend = .02).
• Likewise, a combination of a high intake of UPFs and a low intake of dietary fibres was significantly associated with an increased risk for CRC compared with a low intake of UPFs and fibres (HR, 1.34; P for trend = .03).

IN PRACTICE:

"In summary, the evidence presented in this study does show a significant association between high UPF intake and increased risk of CRC among women in the NOWAC study," the authors wrote, adding that "the results suggest a statistically significant association between high UPF intake and increased risk of cancer in the right side of the colon." They further suggested, "longitudinal studies investigating the relationship between a high UPF intake, UPF subgroups, and CRC risk are needed to determine causality."

SOURCE:

This study was led by Rie Mols, Department of Community Medicine, Faculty of Health Science, UiT The Arctic University of Norway, Tromsø, Norway. It was published online on September 16, 2025, in the British Journal of Nutrition.

LIMITATIONS:

Self-reported food frequency questionnaires provided less detailed information than 24-hour recalls or food diaries. Social desirability bias could have influenced the questionnaire data. The NOVA classification system used in the study was heterogeneous and imprecise. Only baseline dietary data were used, not accounting for potential dietary changes over time. The study's findings may have limited generalisability as it included only women and used nutritional data from a single country.

DISCLOSURES:

This study did not receive any specific grant funding from any funding agency, commercial, or not-for-profit sectors. The authors reported having no relevant conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.