Diet Rich in Processed Foods Linked to Elevated Risk for Colorectal Cancer

TOPLINE:

A dietary pattern linked to the microbial signature of colorectal cancer (CRC) is positively correlated with an increased risk for CRC, particularly for tumors with detectable Fusobacterium nucleatum, the pks strain of Escherichia coli, and enterotoxigenic Bacteroides fragilis (ETBF).

METHODOLOGY:

• To date, no known studies have investigated how a dietary pattern (rather than just individual foods or nutrients) specifically directed at CRC-related microbes may contribute to an increased CRC risk.
• Using stool metagenomes and dietary information from 307 men and 212 women, researchers identified and then validated a dietary pattern specifically linked to an established CRC-related gut microbial signature, which they termed the CRC Microbial Dietary Score (CMDS).
• They then investigated the association between CMDS and the risk for CRC in 259,200 participants (50,637 men and 208,563 women) from three large US cohorts where health professionals provided detailed information on various lifestyle factors over long follow-up periods.
• Researchers also analyzed the risk for CRC on the basis of the presence of gut bacteria, such as F nucleatum, pks+ E coli, and ETBF, in the tumor tissues of the participants who underwent surgical resection for CRC.

TAKEAWAY:

• The CMDS was characterized by high intake of processed foods and low intake of fiber-rich foods.
• Over 6,467,378 person-years assessed in the three US cohorts, 3854 cases of incident CRC were documented, with 1172, 1096, and 1119 cases measured for F nucleatum, pks+ E coli, and ETBF, respectively.
• A higher CMDS was associated with an increased risk for CRC after adjusting for putative CRC risk factors (adjusted hazard ratio [HR], 1.25; P_trend < .001).
• The association between CMDS and the risk for CRC was stronger for tumors with detectable levels of F nucleatum (HR, 2.51; P_trend < .001), pks+ E coli (HR, 1.68; P_trend = .005), and ETBF (HR, 2.06; P_trend = .016).

IN PRACTICE:

“A dietary pattern with a low consumption of processed foods may help prevent colorectal cancer through modulation of the gut microbiome. The dietary pattern modulating the colorectal cancer–related gut microbial signature may particularly help prevent tumoral microbial positive colorectal cancer, which tends to have a worse prognosis,” the authors wrote.

SOURCE:

This study, led by Kai Wang and Chun-Han Lo, Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, was published online in Gastroenterology.

LIMITATIONS:

The study’s observational design may have limited the ability to establish causality between dietary patterns and the risk for CRC. The inclusion of participants who were all health professionals from a predominantly White US population may have limited the generalizability of the findings to other populations. The reliance on self-reported dietary data may have introduced recall bias and affected the accuracy of the dietary pattern assessed.

DISCLOSURES:

This work was supported by various sources, including the National Institutes of Health and the Cancer Research UK Grand Challenge Award. One author served as a consultant for some pharmaceutical companies, and another received funding from various sources, both unrelated to this study.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version of this article first appeared on Medscape.com.