Colorectal Cancer and Sulfur-Metabolizing Bacteria

Colorectal cancer (CRC) has been linked to sulfur-metabolizing bacteria that convert dietary sulfur to hydrogen sulfide, with not many studies available.

In a new study conducted by Yiqing Wang and team, it was found that adherence to the sulfur microbial diet was linked to an increased risk of colorectal cancer (CRC). This study suggests that sulfur-metabolizing bacteria may mediate the association between diet and colorectal cancer risk and could potentially be targeted for risk mitigation.

The findings of this study were published in the Journal of American Medical Association on 12th November, 2021.

Data from the Health Professionals Follow-up Study (1986-2014), the Nurses' Health Study (1984-2016), and the Nurses' Health Study II were used in this prospective cohort study (1991-2017). Participants were male and female registered nurses in the United States who were free of inflammatory bowel disease and cancer at the start of the study, with a subsample of participants providing stool samples from 2012 to 2014. From September 1, 2020, to June 1, 2021, statistical analysis was carried out. A dietary pattern identified through taxonomic and functional profiling of gut metagenome data that was most closely associated with 43 sulfur-metabolizing bacteria.

During 5,278,048 person-years of follow-up, 3,217 incident cases of CRC (1.5 percent) were documented among 214,797 participants (46,550 men and 168,247 women). In a subsample of 307 men and 212 women, the sulfur microbial diet was characterized by:

• High intakes of low-calorie beverages, French fries, red meats, and processed meats
• Low intakes of fruits, yellow vegetables, whole grains, legumes, leafy vegetables, and cruciferous vegetables

After controlling for other risk factors, higher adherence to the sulfur microbial diet was associated with an increased risk of CRC, with a hazard ratio (HR) of 1.27 comparing the highest vs lowest quintile of diet score. Greater adherence to the sulfur microbial diet was associated with distal colon cancer but not proximal colon cancer when assessed by anatomical subsites.

In conclusion, the sulfur microbial diet, defined by high intakes of low-calorie drinks, red meats, and processed meats and low intakes of fruits, whole grains, and vegetables, was found to be associated with an increased risk of CRC in this cohort study, implying a plausible microbial mediation for diet-CRC associations and the potential of using dietary modification as a risk reduction strategy in CRC.

Reference: Wang Y, Nguyen LH, Mehta RS, Song M, Huttenhower C, Chan AT. Association Between the Sulfur Microbial Diet and Risk of Colorectal Cancer. JAMA Netw Open. 2021;4(11):e2134308. doi:10.1001/jamanetworkopen.2021.34308