March 15 (UPI) -- Researchers at the University of Illinois at Urbana-Champaign have found significantly higher numbers of sulfide-producing bacteria -- which may be linked to higher rates of colon cancer -- in African Americans.
African Americans have a significantly higher incidence of colon cancer with 33.5 colon cancer cases per every 100,000 in 2013 compared with 26.8 per 100,000 whites.
Researchers worked on the study to determine the cause of the disparities among the groups.
The study examined colonic tissue biopsies from 197 African Americans and 132 non-Hispanic whites in the United States collected over a two-year period and found African-Americans have more sulfide-producing bacteria in their colon than non-Hispanic whites.
Sulfide-producing bacteria is normally found in the gut but an overabundance of sulfide in the colon can lead to inflammation and can damage DNA.
"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," Rex Gaskins, animal sciences professor at the University of Illinois, said in a press release. "You have to have a genotoxin to have colon cancer. And sulfide is a genotoxin."
The study also found Bilophila wadsworthia, a bacterium that produces hydrogen sulfide from amino acid taurine, was much more abundant in African Americans with colon cancer than in healthy individuals, and was not a risk factor for non-Hispanic whites.
"These bacteria are using nutrients associated with an animal-based diet," Gaskins said.
Researchers have struggled to explain the disparity. Previous studies have shown Native Africans have significantly lower rates of colon cancer than African Americans, pointing to environmental factors such as dietary habits as playing a key role in the risk of colon cancer than genetics.
A study in 2014 found that when South African Zulus were switched from a low-fat, high-fiber diet to a diet with more meat and animal fat, there was a significant increase in sulfide-producing bacteria found in the colon in less than a two-week time period.
"We are now beginning to connect the dots between these dietary factors and one's risk of developing colon cancer," Gaskin said. "Our research adds to the evidence that the microbes that inhabit the colon are part of the equation and should not be overlooked."
The study was published in the journal Gut.