Eating more fiber could reduce ‘forever chemicals' in bodies, study suggests

The Guardian

11-05-2025

Consuming higher amounts of fiber reduces levels of toxic Pfas 'forever chemicals' in human bodies, a new peer-reviewed pilot study suggests.
The research found fiber most effectively reduces Pfos and Pfoa, among the two most common and dangerous Pfas. Each can stay in bodies for years, and federal data shows virtually everyone has the chemicals in their blood.
The researchers are 'excited' about the results of studies on mice and a small human population, said Jennifer Schlezinger, a paper co-author with Boston University. A larger study is in the works.
'We're still mid-experiment but we're seeing very promising things,' she said. 'The key is that this is feasible, accessible and economical.'
Pfas are a class of about 15,000 compounds most frequently used to make products water-, stain- and grease-resistant. They have been linked to cancer, birth defects, decreased immunity, high cholesterol, kidney disease and a range of other serious health problems. They are dubbed 'forever chemicals' because they do not naturally break down in the environment.
The US Environmental Protection Agency has found no level of exposure to Pfos or Pfoa in drinking water is safe. They have a half-life in human blood of anywhere from two to five years, by most estimates. That means the body expels half the amount of the chemical that is in blood during that period. Depending on blood levels, it can take decades to fully expel Pfas.
Military bases are often Pfas hotspots that have exposed untold numbers of service members to the chemicals, and the US Department of defense is funding the research.
The authors theorize that dietary fibers form a gel that may stop cells lining the gut from absorbing the Pfas. They note that fibers form a gel that impedes the absorption of bile acids, leading to increased bile acid elimination in feces.
Bile acids are chemically similar to long-chain Pfas, and the Pfas can move into the gut with the bile. The mechanism in the gel-forming dietary fibers that eliminates bile acid seems to do the same thing for Pfas.
Schlezinger said insoluble and soluble fibers were needed, and those can be added to a glass of juice. Oat beta glucan is also effective. It should be taken with meals because that is when the body largely produces bile, which needs to be timed with fiber consumption.
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Pfoa and Pfos are classified as 'long chain' Pfas, which means that they are among larger compounds in the chemical class. The fiber seemed to generally work well at capturing and discharging those via feces, but did not work as well for smaller 'short-chain' Pfas.
Short-chain Pfas are excreted through urine, but long chains are not.
Cholestyramine, a cholesterol drug, has also been used to reduce Pfas blood levels. But it has been found to create frequent, large, hard stools in mice, Schlezinger said. Fiber, by contrast, creates easy-to-pass stools, and has added health benefits, she noted.