Gut microbes could protect us from toxic ‘forever chemicals’
PFAS have been linked with a range of health issues including decreased fertility, developmental delays in children, and a higher risk of certain cancers and cardiovascular diseases.
Scientists at the University of Cambridge have identified a family of bacterial species, found naturally in the human gut, that absorb various PFAS molecules from their surroundings. When nine of these bacterial species were introduced into the guts of mice to ‘humanise’ the mouse microbiome, the bacteria rapidly accumulated PFAS eaten by the mice - which were then excreted in faeces.
The researchers also found that as the mice were exposed to increasing levels of PFAS, the microbes worked harder, consistently removing the same percentage of the toxic chemicals. Within minutes of exposure, the bacterial species tested soaked up between 25% and 74% of the PFAS.
The results are the first evidence that our gut microbiome could play a helpful role in removing toxic PFAS chemicals from our body - although this has not yet been directly tested in humans.
The researchers plan to use their discovery to create probiotic dietary supplements that boost the levels of these helpful microbes in our gut, to protect against the toxic effects of PFAS.
The results are published in the journal Nature Microbiology.
PFAS (Perfluoroalkyl and Polyfluoroalkyl Substances) can’t be avoided in our modern world. These man-made chemicals are in many everyday items including waterproof clothing, non-stick pans, lipsticks and food packaging, used for their resistance to heat, water, oil and grease. But because they take thousands of years to break down, they are accumulating in large quantities in the environment – and in our bodies.
Dr Kiran Patil, in the University of Cambridge’s MRC Toxicology Unit and senior author of the report, said: “Given the scale of the problem of PFAS ‘forever chemicals’, particularly their effects on human health, it’s concerning that so little is being done about removing these from our bodies.”
“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.”
Dr Indra Roux, a researcher at the University of Cambridge’s MRC Toxicology Unit and a co-author of the study said: “The reality is that PFAS are already in the environment and in our bodies, and we need to try and mitigate their impact on our health now. We haven’t found a way to destroy PFAS, but our findings open the possibility of developing ways to get them out of our bodies where they do the most harm.”
There is increasing concern about the environmental and health impacts of PFAS, and in April 2025 the UK launched a parliamentary inquiry into their risks and regulation.
There are over 4,700 PFAS chemicals in widespread use. Some get cleared out of the body in our urine in a matter of days, but others with a longer molecular structure can hang around in the body for years.
Dr Anna Lindell, a researcher at the University of Cambridge’s MRC Toxicology Unit and first author of the study said: “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.”
Lindell and Patil have co-founded a startup, Cambiotics, with serial entrepreneur Peter Holme Jensen to develop probiotics that remove PFAS from the body, and they are investigating various ways of turbo-charging the microbes’ performance. Cambiotics is supported by Cambridge Enterprise, the innovation arm of the University of Cambridge, which helps researchers translate their work into globally-leading economic and social impact.
While we wait for new probiotics to become available, the researchers say the best things we can do to help protect ourselves against PFAS are to avoid PFAS-coated cooking pans, and use a good water filter.
The research was funded primarily by the Medical Research Council, National Institute for Health Research, and Wellcome.
ReferenceLindell, AE: ‘Human gut bacteria bioaccumulate per- and polyfluoroalkyl substances.’ Nature Microbiology, July 2025. DOI: 10.1038/s41564-025-02032-5
Scientists have discovered that certain species of microbe found in the human gut can absorb PFAS - the toxic and long-lasting ‘forever chemicals.’ They say boosting these species in our gut microbiome could help protect us from the harmful effects of PFAS.
“Given the scale of the problem of PFAS ‘forever chemicals’, particularly their effects on human health, it’s concerning that so little is being done about removing these from our bodies.”Kiran PatilPeter Northrop / MRC Toxicology UnitPFAS accumulation in gut bacteria
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Taking a closer look at life
A team at Cambridge is helping to drive biological discovery through innovation in microscope technologies
Placenta and hormone levels in the womb may have been key driver in human evolution
Dr Alex Tsompanidis, senior researcher at the Autism Research Centre in the University of Cambridge, and the lead author of this new study, said: “Small variations in the prenatal levels of steroid hormones, like testosterone and oestrogen, can predict the rate of social and cognitive learning in infants and even the likelihood of conditions such as autism. This prompted us to consider their relevance for human evolution.”
One explanation for the evolution of the human brain may be in the way humans adapted to be social. Professor Robin Dunbar, an Evolutionary Biologist at the University of Oxford and joint senior author of this new study said: “We’ve known for a long time that living in larger, more complex social groups is associated with increases in the size of the brain. But we still don’t know what mechanisms may link these behavioural and physical adaptations in humans.”
In this new paper, published today in Evolutionary Anthropology, the researchers now propose that the mechanism may be found in prenatal sex steroid hormones, such as testosterone or oestrogens, and the way these affect the developing brain and behaviour in humans.
Using ‘mini-brains’ – clusters of human neuronal cells that are grown in a petri dish from donors’ stem cells – other scientists have been able to study, for the first time, the effects of these hormones on the human brain. Recent discoveries have shown that testosterone can increase the size of the brain, while oestrogens can improve the connectivity between neurons.
In both humans and other primates such as chimpanzees and gorillas, the placenta can link the mother’s and baby’s endocrine systems to produce these hormones in varying amounts.
Professor Graham Burton, Founding Director of the Loke Centre of Trophoblast Research at the University of Cambridge and coauthor of the new paper, said: “The placenta regulates the duration of the pregnancy and the supply of nutrients to the fetus, both of which are crucial for the development of our species’ characteristically large brains. But the advantage of human placentas over those of other primates has been less clear.”
Two previous studies show that levels of oestrogen during pregnancy are higher in human pregnancies than in other primate species.
Another characteristic of humans as a species is our ability to form and maintain large social groups, larger than other primates and other extinct species, such as Neanderthals. But to be able to do this, humans must have adapted in ways that maintain high levels of fertility, while also reducing competition in large groups for mates and resources.
Prenatal sex steroid hormones, such as testosterone and oestrogen, are also important for regulating the way males and females interact and develop, a process known as sex differentiation. For example, having higher testosterone relative to oestrogen leads to more male-like features in anatomy (e.g., in physical size and strength) and in behaviour (e.g., in competition).
But in humans, while these on-average sex differences exist, they are reduced, compared to our closest primate relatives and relative to other extinct human species (such as the Neanderthals). Instead, anatomical features that are specific to humans appear to be related more to aspects of female rather than male biology, and to the effects of oestrogens (e.g., reduced body hair, and a large ratio between the second and fourth digit).
The researchers propose that the key to explain this may lie again with the placenta, which rapidly turns testosterone to oestrogens, using an enzyme called aromatase. Recent discoveries show that humans have higher levels of aromatase compared to macaques, and that males may have slightly higher levels compared to females.
Bringing all these lines of evidence together, the authors propose that high levels of prenatal sex steroid hormones in the womb, combined with increased placental function, may have made human brains larger and more interconnected. At the same time, a lower ratio of androgens (like testosterone) to oestrogens may have led to reductions in competition between males, while also improving fertility in females, allowing humans to form larger, more cohesive social groups.
Professor Simon Baron-Cohen, Director of the Autism Research Centre at the University of Cambridge and joint senior author on the paper, said: “We have been studying the effects of prenatal sex steroids on neurodevelopment for the past 20 years. This has led to the discovery that prenatal sex steroids are important for neurodiversity in human populations. This new hypothesis takes this further in arguing that these hormones may have also shaped the evolution of the human brain.”
Dr Tsompanidis added: “Our hypothesis puts pregnancy at the heart of our story as a species. The human brain is remarkable and unique, but it does not develop in a vacuum. Adaptations in the placenta and the way it produces sex steroid hormones may have been crucial for our brain’s evolution, and for the emergence of the cognitive and social traits that make us human.”
ReferenceTsompanidis, A et al. The placental steroid hypothesis of human brain evolution. Evolutionary Anthropology; 20 June 2025; DOI: 10.1002/evan.70003
The placenta and the hormones it produces may have played a crucial role in the evolution of the human brain, while also leading to the behavioural traits that have made human societies able to thrive and expand, according to a new hypothesis proposed by researchers from the Universities of Cambridge and Oxford.
Our hypothesis puts pregnancy at the heart of our story as a speciesAlex TsompanidisNadzeya Haroshka (Getty Images)Models of a fetus in the womb and of the brain
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Learning to thrive in diverse African habitats allowed early humans to spread across the world
Today, all non-Africans are known to have descended from a small group of people that ventured into Eurasia around 50,000 years ago. However, fossil evidence shows that there were numerous failed dispersals before this time that left no detectable traces in living people.
In a new study published today in the journal in Nature, scientists say that from around 70,000 years ago, early humans began to exploit different habitat types in Africa in ways not seen before.
At this time, our ancestors started to live in the equatorial forests of West and Central Africa, and in the Sahara and Sahel desert regions of North Africa, where they encountered a range of new environmental conditions.
As they adapted to life in these diverse habitats, early humans gained the flexibility to tackle the range of novel environmental conditions they would encounter during their expansion out of Africa.
This increase in the human niche may have been the result of social adaptations, such as long-distance social networks, which allowed for an increase in cultural exchange. The process would have been self-reinforcing: as people started to inhabit a wider proportion of the African continent, regions previously disconnected would have come into contact, leading to further exchanges and possibly even greater flexibility. The final outcome was that our species became the ultimate generalist, able to tackle a wider range of environments.
Andrea Manica, Professor of Evolutionary Ecology in the University of Cambridge’s Department of Zoology, who co-led the study with Professor Eleanor Scerri from the Max Plank Institute of Bioanthropology in Germany, said: “Around 70,000-50,000 years ago, the easiest route out of Africa would have been more challenging than during previous periods, and yet this expansion was big - and ultimately successful.”
Manica added: “It’s incredibly exciting that we were able to look back in time and pinpoint the changes that enabled our ancestors to successfully migrate out of Africa.”
Dr Emily Hallett of Loyola University Chicago, co-lead author of the study, said: “We assembled a dataset of archaeological sites and environmental information covering the last 120,000 years in Africa. We used methods developed in ecology to understand changes in human environmental niches - the habitats humans can use and thrive in - during this time.”
Dr Michela Leonardi at the University of Cambridge and London’s Natural History Museum, the study’s other lead author, said: “Our results showed that the human niche began to expand significantly from 70,000 years ago, and that this expansion was driven by humans increasing their use of diverse habitat types, from forests to arid deserts.”
Many explanations for the uniquely successful dispersal out of Africa have previously been made, from technological innovations, to immunities granted by interbreeding with Eurasian hominins. But there is no evidence of technological innovation, and previous interbreeding does not appear to have helped the long-term success of previous attempts to spread out of Africa.
“Unlike previous humans dispersing out of Africa, those human groups moving into Eurasia after around 60-50,000 years ago were equipped with a distinctive ecological flexibility as a result of coping with climatically challenging habitats,” said Scerri. “This likely provided a key mechanism for the adaptive success of our species beyond their African homeland.”
Previous human dispersals out of Africa - which were not successful in the long term - seem to have happened during particularly favourable windows of increased rainfall in the Saharo-Arabian desert belt, which created ‘green corridors’ for people to move into Eurasia.
The environmental flexibility developed in Africa from around 70,000 years ago ultimately resulted in modern humans’ unique ability to adapt and thrive in diverse environments, and to cope with varying environmental conditions throughout life.
This research was supported by funding from the Max Planck Society, European Research Council and Leverhulme Trust.
Adapted from a press release by the Max Planck Institute of Geoanthropology, Germany
Reference: Hallett, E. Y. et al: ‘Major expansion in the human niche preceded out of Africa dispersal.’ Nature, June 2025. DOI: 10.1038/s41586-025-09154-0.
Before the ‘Out of Africa’ migration that led our ancestors into Eurasia and beyond, human populations learned to adapt to new and challenging habitats including African forests and deserts, which was key to the long-term success of our species’ dispersal.
It’s incredibly exciting that we were able to look back in time and pinpoint the changes that enabled our ancestors to successfully migrate out of Africa.Andrea ManicaOndrej Pelanek and Martin PelanekAfrican Bush Elephant
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