A Common Additive That Could Harm Your Gut

By Jane Farrell

Triclosan, an antimicrobial additive contained in thousands of consumer products, causes colon inflammation and exacerbates colon cancer in mice, scientists say.

A news release from the American Association for the Advancement of Science (AAAS) says the results of the analysis indicate that health authorities might want to reinvestigate regulatory policies about the usage of triclosan.

According to the news release, the substance is found in more than 2,000 consumer products ranging from toothpaste to cosmetics and toys. In fact, it is so common that the entire U.S. population is exposed to it at some point.

Research has suggested that triclosan can have toxic effects at high doses, but the health effects of lower concentrations that a person might be exposed to remain unclear. Here, Haixia Yang and colleagues from the AAAS fed mice with food containing various concentrations of triclosan for three weeks. They found that mice treated with a concentration of triclosan that reflects the concentrations reported in human blood samples displayed more systemic and colonic inflammation compared to control animals. Furthermore, triclosan exposure increased the severity of colon inflammation in mouse models of inflammatory bowel disease (IBD) – an effect that persisted even when low doses of the chemical were administered. Triclosan treatment also increased tumor size and reduced survival in a separate group of rodents with colon cancer. Interestingly, triclosan reduced the diversity of commensal bacteria in the gut of mice, and germ-free mice were protected from the harmful effects, suggesting its pro-inflammatory actions may arise due to alteration of the gut microbiome. The authors stress that further studies should assess the impact of triclosan on human gut health and determine whether individuals with IBD or colon cancer could be more vulnerable to any adverse effects.

The findings were published in Science Translational Medicine.