March 20, 2017
1 min read

Sulfidogenic bacteria linked to higher colorectal cancer risk in black patients

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Sulfidogenic bacteria are more abundant in the colonic mucosa of black patients vs. non-Hispanic white patients, and these bacteria may be linked to their higher-than-average risk for colorectal cancer, according to new research.

While these bacteria normally occur in the human gut microbiome, an overabundance of sulfide in the colon can cause inflammation and damage DNA, Rex Gaskins, PhD, an animal sciences professor at University of Illinois, said in a press release.

“We found that African-Americans have an increased abundance of bacteria that make hydrogen sulfide, which we demonstrated more than a decade ago to be a potent genotoxin,” he added. “You have to have a genotoxin to have colon cancer, and sulfide is a genotoxin.”

Gaskins and colleagues evaluated colonic tissue biopsies from 197 black participants and 132 non-Hispanic white participants with and without colorectal cancer, which were obtained between 2010 and 2012 at five medical centers in Chicago. They performed quantitative PCR and 16S rDNA sequencing to compare the abundance of sulfidogenic bacteria in uninvolved colonic mucosa of black and non-Hispanic white CRC patients, and in the normal mucosa of black and non-Hispanic white controls. They also examined bacterial, racial, disease status and dietary correlations.

Overall, the abundance of sulfidogenic bacteria was 10 times higher in blacks compared with non-Hispanic whites irrespective of disease status (P < .001).

Further, the sulfidogenic bacteria Bilophila wadsworthia and Pyramidobacter spp were significantly more abundant in black patients with CRC compared with black controls.

Finally, dietary intake of fat and animal protein — which was significantly higher among black participants, and is a known risk factor for CRC — correlated positively with a higher abundance of sulfidogenic bacteria, while dairy and calcium intake were negatively correlated. However, participants self-reported their dietary information by questionnaire, which the researchers acknowledged is a limitation of the study.

“We are now beginning to connect the dots between these dietary factors and one’s risk of developing colon cancer risk,” Gaskins said in the press release. “Our research adds to the evidence that the microbes that inhabit the colon are part of the equation and should not be overlooked.” – by Adam Leitenberger

Disclosures: The researchers report no relevant financial disclosures.