Gut microbes may flush ‘forever chemicals’ from the body

Expelling toxic “forever chemicals” from the body may take guts — or at least, their microbes.

Some microbes found in the human gut can absorb some per- and polyfluoroalkyl substances, or PFAS, researchers report July 1 in Nature Microbiology. Mice harboring those bacteria in their guts excreted PFAS in their feces, suggesting microbes are intestinal allies that flush forever chemicals from the body.

Bacteria often encounter many potentially stressful chemicals such as pesticides and have mechanisms to deal with them. But “from the bacterial perspective, chemicals are chemicals,” says Kiran Patil, a molecular biologist at the University of Cambridge. Previous studies had showed that gut microbes can pick up and store unintended targets such as therapeutic drugs. But it was unknown how those bacteria respond to pollutants including PFAS that people might consume in food or water.

PFAS are essential components in waterproof or stain-resistant products, including nonstick cookware and rain gear. But the chemicals are linked to health problems such as high cholesterol, developmental delays and certain cancers, prompting a search for alternatives. PFAS are detectable in nearly all people living in the United States, according to the U.S. Centers for Disease Control and Prevention.

The team exposed human gut bacteria to two common forms of PFAS and other pollutants. At various concentrations, multiple bacterial strains, including E. coli, soaked up PFAS in lab dishes, storing forever chemicals in clumps inside their cells, Patil says. The microbes amassed between 20 and 75 percent of the chemicals with no negative effects.

What’s more, the gut bacteria of so-called “humanized” mice — animals whose intestines have been cleared of existing microbes and replaced with kinds that live in people — had more PFAS in their poop than microbe-free mice. The finding suggests that gut bacteria can carry forever chemicals out of the body in feces.

To determine if the same happens in people, researchers could track differences in gut microbiomes and PFAS levels in people from the same place, Patil says. Or people could take probiotics containing forever chemical-absorbing bacteria to test if levels go down.

Many efforts focus on removing PFAS from the environment, but the findings could help researchers find ways to clear them from the body, too. “Our [gut microbiome] does a lot of things for us,” Patil says. “And maybe they are doing something positive to help us with PFAS.”