The gut bacteria composition of people at risk for colorectal cancer differs from that of healthy people, according to a recent study published in the Journal of the National Cancer Institute.1 Researchers from the New York University School of Medicine analyzed stool samples from 141 patients—47 of which had colorectal cancer—and found lower bacterial diversity in patients with colon cancer.
Bacterial diversity is the hallmark of a healthy gut. The more diverse the gut bacteria, the less likely potential pathogens can gain the upper hand and lead to infection. This study suggests that lower gut diversity may also lead to increases in certain bacteria and decreases in others; colon cancer patients had higher levels of Fusobacterium and Porphyromonas bacteria than did healthy subjects. Fusobacterium has been found to contribute to colitis,2 which involves inflammation of the colon, and both Fusobacterium and Porphyromonas have been linked to periodontal disease,3 which itself has been linked to colon cancer.4 Perhaps based on the latest research, gingival and oral cultures may soon be a preventative biomarker of inflammatory bowel disease and colon cancer.
Patients with colon cancer were also found to have decreased levels of the Clostridia class of bacteria. You may recognize the name Clostridia because one bacterium from this class—Clostridium difficile—is a major pathogen that can be deadly. Not all Clostridia are harmful, however. One particular Clostridia family (Lachnosporaceae) and one bacterium within this family (Corpococcus) are both known to efficiently ferment dietary fiber and complex carbohydrates, producing butyrate, a short-chain fatty acid well known to be protective of colon cancer due to its nourishing effects on the lining of the colon. In addition to helping feed the cells that line the colon, butyrate enters the cells and prevents damaged cells from becoming cancerous. Also telling, Clostridia have been found to be less abundant in colon tumors when compared to normal adjacent tissue.3
“In conclusion, this survey of the gut microbiota found that colorectal cancer risk was associated with decreased bacterial diversity in feces; depletion of Gram-positive, fiber-fermenting Clostridia; and increased presence of Gram-negative, pro-inflammatory genera Fusobacterium and Porphyromonas,” stated the researchers. “Because of the potentially modifiable nature of the gut bacteria, our findings may have implications for colorectal cancer prevention.”
Maintaining gut balance is crucial for protection against many conditions, digestive or otherwise. Administration of probiotics (beneficial bacteria) and prebiotics (fibers that feed beneficial bacteria in the gut) has been found to have a protective effect against colon cancer.6 One main reason probiotics and prebiotics are so beneficial is because they promote increased production of butyrate in the colon, just as the beneficial Clostridia do. Achieving gut balance is one of the most important things you can do for your health.
- Ahn J, Sinha R, Pei Z, et al., “Human gut microbiome and risk of colorectal cancer.” J Natl Cancer Inst. 2013 Dec; online ahead of print.
- Ohkusa T, Okayasu I, Ogihara T, et al., “Induction of experimental ulcerative colitis by Fusobacterium varium isolated from colonic mucosa of patients with ulcerative colitis.” Gut. 2003 Jan;52(1):79-83.
- Signat, Rogues C, Poulet P, et al., “Fusobacterium nucleatum in periodontal health and disease.” Curr Issues Mol Biol. 2011;13(2):25-36.
- Ahn J, Segers S, Hayes RB, “Periodontal disease, Porphyromonas gingivalis serum antibody levels and orodigestive cancer mortality.” Carcinogenesis. 2012 May;33(5):1055-8.
- Kostic AD, Gevers D, Pedamallu CS, et al., “Genomic analysis identifies association of Fusobacterium with colorectal carcinoma.” Genome Res. 2012 Feb;22(2):292-8.
- Wollowski I, Rechkemmer G, Pool-Zobel BL, “Protective role of probiotics and prebiotics in colon cancer.” Am J Clin Nutr. 2001 Feb;73(2 Suppl):451S-455S.