In the sprawling war against “forever chemicals,” the human gut might be our most surprising ally yet.

Per- and polyfluoroalkyl substances, or PFAS, are synthetic chemicals used in everything from non-stick cookware to waterproof jackets. But, as it so often happens, the remarkable stability that makes them so useful also makes them dangerous. They don’t break down in nature, they accumulate in the environment, and they build up in our blood and organs. They’re not harmless, either. PFAS have been linked to everything from cancer to fertility issues.

But now, a team of scientists from the University of Cambridge has found that certain gut bacteria can absorb PFAS from their surroundings. They showed (in mouse studies) that these bacteria soaked up significant amounts of PFAS and carried them out of the body in feces. The research, published in Nature Microbiology, opens a striking new avenue for detoxifying humans without complex medical intervention: by feeding the bacteria already inside us.

A large, toxic family

PFAS came into use with the invention of Teflon in 1938. Now, they comprise a large family of over 4,700 chemicals. And they’re not natural; all of them are exclusively synthetic. PFAS are prized for their resistance to things like heat or water. So, they work well for a bunch of different products including cosmetics, food packaging, firefighting foams, and clothing. But they’re also a major public health concern. PFAS take years or even decades to clear from the human body, which is why they’re often called “forever” chemicals.

Once we considered them safe, but now we know better. In Europe alone, the estimated annual cost of health impacts linked to PFAS ranges from €50–80 billion.

We know a lot about PFAS in water supplies and soils. But we don’t yet know that much about how the body deals with these chemicals. That’s where gut bacteria come in.

The Cambridge team tested 89 strains of bacteria, many of them commonly found in the human gut. They discovered that at least 38 could absorb significant amounts of PFAS, especially longer-chain types like PFNA and PFDA, which are among the most stubborn and toxic.

“We found that certain species of human gut bacteria have a remarkably high capacity to soak up PFAS from their environment at a range of concentrations, and store these in clumps inside their cells. Due to aggregation of PFAS in these clumps, the bacteria themselves seem protected from the toxic effects,” says Dr Kiran Patil, in the University of Cambridge’s MRC Toxicology Unit and senior author of the report.

Some of the most effective species include Bacteroides uniformis and Odoribacter splanchnicus. These absorbed over 70% of PFAS from their environment within just minutes. Importantly, the bacteria didn’t just bind PFAS to their outer membranes, they also pulled them inside their cells, where the chemicals formed dense clumps. This mass is then excreted from the body.

Bacteria detox

For now, the study has only been carried out on mice, but there’s a good chance something similar would happen in humans. So, this raises an intriguing possibility. Could we take probiotic supplements (like the ones many people are already taking for digestion) to help flush PFAS from our bodies?

Dr Anna Lindell, a researcher at the University of Cambridge’s MRC Toxicology Unit and first author of the study, believes this is something we should consider.

“We’re all being exposed to PFAS through our water and food — these chemicals are so widespread that they’re in all of us. PFAS were once considered safe, but it’s now clear that they’re not. It’s taken a long time for PFAS to become noticed because at low levels they’re not acutely toxic. But they’re like a slow poison.”

The researchers are now investigating how to enhance these bacteria’s PFAS-absorbing abilities, including through genetic modification or microbial engineering. The fact that bacteria don’t eliminate these PFAS is encouraging.

There’s still a long way to go, however. This new study changes how scientists think about the microbiome’s role in chemical detoxification. Until now, most research has looked at how pollutants affect gut bacteria. This flips the script: gut bacteria can fight back.

The study was published in Nature Microbiology.