Common soap additive linked to colonic inflammation
The common antimicrobial agent, triclosan, has been implicated in colonic inflammation and the disease development of colitis and colitis-associated colon cancer, reveals a study appearing in Science Translational Medicine.
While the study was done in mice, the research team, led by senior author Guodang Zhang of the University of Massachusetts Amherst, US, reported in Science Translational Medicine that “the results, for the first time, suggest that triclosan could have adverse effects on gut heath.” In the study, the researchers looked at the effects of triclosan on colonic inflammation and colon cancer using a variety of mouse models. Zhang noted that triclosan promoted colonic inflammation and colonic tumorigenesis in all the models tested.
Coauthor and food scientist Hang Xiao, added, "In particular, we used a genetically engineered mouse model which develops spontaneous inflammatory bowel disease or IBD. Also, treatment with triclosan significantly increased disease development of IBD in the mice, suggesting that IBD patients may need to reduce exposure to this compound."
In order to elucidate the mechanisms behind the development of IBD and tumorigenesis, the research team found that gut microbiota is critical for the observed adverse effects of triclosan. Feeding triclosan to mice reduced the diversity and changed the composition of the gut microbiome, a result similar to what was observed in a human study conducted by others, said Zhang. Also, triclosan had no effect in a germ-free mouse model where there is no gut microbiome present, nor in a genetically engineered mouse model where there is no Toll-like receptor 4 (TLR4) – an important mediator for host-microbiota communications. "This is strong evidence that gut microbiota is required for the biological effects of triclosan" Zhang points out.
According to coauthors Haixia Yang and Weicang Wang, triclosan is one of the most widely used antimicrobial ingredients and found in more than 2,000 consumer products. It was also revealed that the National Health and Nutrition Examination Survey reported that 75 percent of all urine samples tested in the US showed traces of triclosan. It is among the top ten most common chemicals found in US rivers. [Available at https://www.cdc.gov/biomonitoring/Triclosan_FactSheet.html]
Yang, who is a postdoctoral fellow in the Zhang Laboratory, said: “Because this compound is so widely used, our study suggests that there is an urgent need to further evaluate the impact of triclosan exposure on gut health in preparation for the potential establishment of further regulatory policies.”
Ed: Triclosan is of particular interest to healthcare professionals as it is an ingredient often used as a marketing gimmick in skincare and cleaning products. It is also found in a wide range of hospital disinfectants. In September 2016, the US Food and Drug Administration issued a ruling that over-the-counter consumer antiseptic products containing certain active ingredients can no longer be marketed. In particular, two ingredients were named—triclosan and triclocarban. The ruling was founded on the fear of microbial resistance and hormonal interference, plus the lack of evidence suggesting that the active ingredients were better than simple soap and water in preventing illness and the spread of infections. [https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm517478.htm]