The higher intake of animal fat and meat among African-Americans is a potential environmental risk factor for colorectal cancer, as it changes to composition of their gut microbiota, according to results of a new study.
These findings were published in the journal Gut with the title “Race-Dependent Association Of Sulfidogenic Bacteria With Colorectal Cancer.”
Diets rich in animal protein and fat have been known to increase the risk of colorectal cancer. This is because certain bacteria present in the gut, called sulfidogenic bacteria, use these nutrients to survive and at the same time produce molecules that trigger inflammation and proliferation of cells in the gut, leading to cancer.
The incidence of colorectal cancer is higher among African-Americans than in non-Hispanic whites (33.5 cases vs. 26.8 cases per 100,000 people, respectively). Researchers wondered if the difference could be caused by an abundance of sulfidogenic bacteria in African-Americans.
To test this theory, researchers analyzed gut biopsies from patients with colorectal cancer and healthy individuals from five medical centers in Chicago, and compared the abundance of sulfidogenic bacteria between African-Americans and non-Hispanic whites.
Results confirmed that African-American patients carry a higher abundance of sulfidogenic bacteria compared to the other group, regardless of their disease status. Among the bacteria detected, Bilophila wadsworthia was especially abundant in African-American patients.
“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, co-senior author of the study, said in a news release.
Importantly, fat and protein consumption and daily portions of meat were significantly higher in African-Americans compared to non-Hispanic whites.
“These bacteria are using nutrients associated with an animal-based diet,” Gaskins said.
Together, these results help explain the association between the increased risk of colorectal cancer associated with diets rich in animal meat and fat, and the higher incidence of this disease in African-Americans.
“We are now beginning to connect the dots between these dietary factors and one’s risk of developing colon cancer,” Gaskins added. “Our research adds to the evidence that the microbes that inhabit the colon are part of the equation and should not be overlooked.”