PFAS, better known as “forever chemicals,” have contaminated our environment and our food. Our gut bacteria may help limit the absorption of these substances by our bodies: they sequester them before escorting them out with our stool and into the toilet. Good riddance!
(sidenote:
PFAS (per- and polyfluoroalkyl substances)
Large group of chemicals, also referred to as ‘forever chemicals’, consisting of a more or less long or branched carbon chain and containing at least one fluorinated group. Their extreme persistence in the environment has been understood for a long time. However, other properties of these compounds that are displayed by certain subgroups of PFAS, are concerning:
- potential for bioaccumulation in living organisms;
- high mobility in water, soil and air;
- long-range transport potential; and
- (eco)toxicological effects that impact humans and the environment.
Sources: European Environment Agency: PFAS Pollution in European Waters
Gaillard L, Bernal K, Coumoul X et al. Forever pollutants and human contamination: State of art and challenges around per- and polyfluoroalkyl substances (PFASs).Cah Nut & Diet. 2024. Dec (59);6:349-361.
), or “forever chemicals,” are widely found in everyday objects (fire-resistant materials in our furniture, non-stick pans, etc.), and today they’re turning up in the environment, in our food... and apparently in the bacteria of our gut microbiota. At least, that’s what a study 1 has demonstrated for the first time in mice that were fed 42 PFAS commonly found in our diet.
4,700
Per- and polyfluoroalkyl substances (PFAS) include over 4,700 compounds. ¹
€50–80 billion
The annual health-related cost of PFAS exposure is estimated to be 50–80 billion Euros across Europe. ¹
More or less bioaccumulating bacteria
Result: several of their gut bacteria massively bioaccumulate certain PFAS. Their surprising favorites: large-sized PFAS.
Among the 89 bacterial strains studied, 38 turned out to be formidable PFAS “vacuum cleaners,” particularly those belonging to the Bacteroidota family. Even at very low doses, PFAS are absorbed in just 3 minutes and accumulate within the bacteria at concentrations up to 50 times higher than in the bacteria’s surrounding environment.
100
The half-life of very long-chain PFAS — the time it takes for half of a substance to degrade or be eliminated — could range from 10 to 100 years, highlighting their extreme persistence in the environment. In a living organism, the half-life varies from a few hours to several years depending on the molecule. 2
No harm done!
As surprising as it may seem, despite their toxicity and their “soapy” effect (PFAS are known and used for their surfactant properties), PFAS appear to have little impact on the functioning of gut bacteria.
They accumulate inside these microorganisms in the form of compact clusters, which, according to the authors, may limit their toxicity.
Even better, the bacteria seem to adapt: after about a hundred generations, the descendants of Bacteroides uniformis or E. coli grow faster than their predecessors, despite the continued presence of PFAS which they continue to trap efficiently.
Even though the bacteria survive well, some changes are nevertheless observed in their functioning in response to this stress, although, at this stage, it is not yet possible to assess the consequences for the microbiota or the host.
But above all – and this is the study’s major discovery – the bacteria that trap PFAS facilitate their natural elimination. In mice transplanted with human gut microbiota, PFAS were found in greater amounts in their droppings than in mice without microbiota. And the greater the bioaccumulation potential of the bacteria in the digestive system, the more significant this elimination becomes.
Therefore, gut microbiota, especially when rich in bioaccumulating bacteria, may act as a kind of natural extractor of PFAS, trapping these pollutants inside their cytoplasm before carrying them out with the stool. Destination: the sewers!
These results provide new insight into the impact of PFAS on the microbiota, although further studies are needed to better understand the role of these bioaccumulating bacteria in our health.
Sucralose is a widely consumed sweetener that alters gut microbiota, indirectly impacting the immune system via T cell metabolism, and with it, responses to immunotherapy.
The gut microbiota is a major regulator of responses to (sidenote:
Immune checkpoint inhibitors (ICIs)
Therapies that seek to remove the mechanisms that inhibit the immune system’s response to cancer cells. Targeted checkpoints include Programmed Death-1 (PD-1), Programmed Death-Ligand 1 (PDL-1), and cytotoxic T-lymphocyte associated protein 4 (CTLA-4). Lifting these brakes allows the immune system to recognize and attack cancer cells. ) in several cancers, including melanoma and non-small-cell lung cancer (NSCLC). However, the impact of dietary factors such as sweeteners remains poorly understood. For example, sucralose is a widely consumed sweetener known to alter the microbiota. Does it play a role? To answer this question, researchers studied the link between consumption of this sweetener and the effectiveness of anti-PD-1 treatments.
Diminished outlook among sweetener users
The analysis involved three patient cohorts: 91 patients with advanced melanoma, 41 with advanced NSCLC, and 25 with high-risk resectable melanoma, all treated with anti-PD-1 immunotherapy.
High sucralose consumption (> 0.16 mg/kg/day) is associated with poorer clinical outcomes:
in advanced melanoma, median progression-free survival (PFS) decreases from 13 to 8 months
in NSCLC, it falls from 18 to 7 months, with a lower treatment response rate (12% vs. 49%)
in resectable melanoma, treatment response is lower, as is relapse-free survival (19 vs. 25 months).
Similar trends were observed with another sweetener, acesulfame, but not with aspartame or saccharin.
Underlying mechanisms involving T cells
Murine models have confirmed these findings and made it possible to explore the underlying mechanisms. Sucralose consumption leads to resistance to anti-PD-1 immunotherapy and significantly increased tumor growth, whereas sucrose (table sugar) consumption has no effect. The mechanisms appear to involve T cells: sucralose consumption has deleterious effects on several T cell processes (proliferation, cytotoxic function, metabolism). These effects do not appear to be limited to cancer alone, but instead may affect various diseases, from cancer to seasonal viral infections.
24-37%
Nonnutritive sweeteners (NNS) intake is prevalent in the general population, both in lean and obese individuals alike, with 24% to 37% of US adults reporting some NNS intake in dietary recall surveys.
The gut microbiota, necessary and sufficient
The effect of sucralose depends entirely on the gut microbiota: fecal microbiota transplants (FMT) from mice that consume sucralose are sufficient to reduce the effectiveness of immunotherapy in naive mice. Conversely, an FMT from mice that respond to treatment restores the effectiveness of immunotherapy in mice that consume sucralose.
More specifically, sucralose alters microbiota composition, favoring bacteria that degrade arginine and thus reducing arginine levels in feces, serum, and tumors. Arginine is a key metabolite in T cell metabolism, which explains why T cells become depleted. Remarkably, supplementation with arginine or citrulline (a precursor of arginine) restores T-cell function and overcomes sucralose-induced resistance to immunotherapy in mice.
Thus, certain dietary factors, such as artificial sweeteners, appear to represent a mechanism of resistance to immune checkpoint inhibitors. Confirmation of any causal link will require prospective studies.
Certain bacteria in the gut microbiota bioaccumulate PFAS. They accumulate these pollutants inside their cells at concentrations up to 50 times higher than their environment. An unexpected mechanism that may support their elimination through stool.
PFAS1, also known as “forever chemicals,” have invaded our daily lives: fire-retardant foams in our sofas, waterproof clothing, non-stick pans, and more. Yet interactions between certain PFAS accumulating in the environment and bacteria have already been documented: some strains of Pseudomonas, isolated from sites contaminated with PFAS, bioaccumulate a sulfur-containing PFAS, while certain lactobacilli ‘bio-bind’ with another PFAS. How does the gut microbiota, the key interface between dietary exposure to these substances and our body, come into play? This question is explored in studies released in Nature Microbiology in 2025.
Strong and rapid bioaccumulation
By testing 89 microbial strains, researchers found that PFAS bioaccumulation capacity varies greatly from one bacterium to another: 38 strains, including bacteria belonging to the Bacteroidota phylum, showed particularly high bioaccumulation ability, even at low PFAS concentrations. The process proved to be very fast (just a few minutes), irreversible (no release) and highly efficient: the intracellular PFAS concentration in bacteria is about 50 times higher than that of the medium, reaching the millimolar range. The longer the PFAS molecule, the more strongly it is bioaccumulated by the bacterium.
4,700
Per- and polyfluoroalkyl substances (PFAS) include >4,700 compounds.
€50–80 billion
The annual health-related cost of PFAS exposure is estimated to be 50–80 billion Euros across Europe.
Little impact on bacterial function
Surprisingly, bioaccumulated PFAS have little effect on bacterial life: their physicochemical properties cause them to aggregate into dense intracellular clusters, limiting their cellular toxicity and effects. Bacteria even appear to adapt over generations: the 100th generation of B. uniformis and E. coli ΔtolC grows faster than their ancestors in the presence of PFAS while maintaining their bioaccumulation capacities.
Although it does not compromise bacterial viability, bioaccumulation nonetheless induces certain changes, particularly in the most accumulative strains: alterations are observed in membrane proteins (particularly efflux pumps responsible for excreting toxins) and in the secretion of amino acids involved in the gut–brain axis or stress response.
Did you know?
The half-life of very long-chain PFAS — the time it takes for half of a substance to degrade or be eliminated — could range from 10 to 100 years, highlighting their extreme persistence in the environment. In a living organism, the half-life varies from a few hours to several years depending on the molecule.2
PFAS excreted in stool
Finally, the presence of bioaccumulating bacteria in the intestine increases the elimination of PFAS: the stool of mice carrying human microbiota is significantly richer in PFAS than that of mice without microbiota. And PFAS excretion is all the more effective when intestinal flora bacteria are strong bioaccumulators. For now, however, the authors are not drawing any conclusions about possible health benefits.
Why does one infant’s cold stay mild while another’s leads to bronchiolitis? A new study reveals the answer isn't just the virus, but the microbial ecosystem in the nose that acts as the immune system’s first line of defense.
Every parent knows the cascade of events: a simple cough and runny nose can quickly progress into a full-blown ear infection, or worse, bronchiolitis. We’ve long blamed the virus, but a critical new study in Nature Communications 1 reveals that the virus is often just the opening act. The real drama unfolds within your baby’s (sidenote:
ENT Microbiota
This refers to the specific community of microorganisms (bacteria, fungi, viruses) that reside in the interconnected regions of the ear, nose, and throat. This ecosystem is distinct from the gut microbiota and plays a crucial, direct role in local immunity and respiratory health.
), the complex community of bacteria in the nose and throat that serves as the frontline of the immune system. This research provides a new framework for understanding respiratory health during the crucial first year of life.
Researchers followed 300 infants from birth, meticulously tracking their health and analyzing over 2,400 nasal samples. The data reveals a clear mechanism: a viral infection, whether from a common Rhinovirus or Respiratory Syncytial Virus (RSV), profoundly alters the landscape of the respiratory system.
Respiratory syncytial virus (RSV)
Causes 3.6 million hospitalizations each year and approximately 100,000 deaths among children under the age of 5. ²
The presence of a virus was shown to increase the odds of infant (sidenote:
Bacterial Colonization
This is the persistent presence and growth of bacteria on a host surface, such as the nasal passages, without causing clinical signs of disease. It is a necessary prerequisite for infection but is distinct from it, representing an asymptomatic carrier state.
) with Haemophilus influenzae by 44% and Streptococcus pneumoniae by a striking 83%.
For infants already carrying S. pneumoniae, a viral infection amplified its (sidenote:
Colonization Density
This is a quantitative measure of the bacterial load, or the number of a specific bacterium present in a sample, rather than a simple presence/absence result. High colonization density can increase the risk of a pathogen transitioning from a harmless colonizer to an active infection.
) nearly four-fold, creating a high-risk environment for invasive disease.
Here is the most significant insight from the study. The virus doesn’t just help harmful bacteria; it actively sabotages the beneficial microbes that keep them in check.
The analysis identified specific protective species, like Corynebacterium, that normally prevent pathogens from gaining a foothold. The data showed that a viral infection leads to a direct loss of these beneficial bacteria. It is this depletion that opens the door for pathogens to colonize.
In a counterintuitive twist, the same viral infections were associated with a 55% lower odds of acquiring Staphylococcus aureus, revealing just how specific and complex these microbial interactions are.
Shaping a resilient immune system for your child
This work emphasizes that a healthy ENT microbiota is not optional; it is a fundamental component of early life immunity.
In fact, the composition of an infant's nasal microbiota was a more accurate predictor of future bacterial acquisition than standard clinical risk factors. The development of this ecosystem is shaped by the (sidenote:
Exposome
It was in 2005, in an article published in the journal Cancer Epidemiology, Biomarkers & Prevention, that Dr. Christopher Wild first defined the exposome as "life-course environmental exposures (including lifestyle factors), from the prenatal period onwards. It is a complex and dynamic representation that integrates the chemical, microbiological, physical, recreational and medicinal environments, lifestyle, diet and infections." Source), with factors like breastfeeding playing a key role in seeding and nourishing beneficial species.
Understanding these early microbial dynamics is essential, as they lay the foundation for long-term respiratory health and may influence the future risk of conditions like recurrent infections and asthma.
How do you evict VRE post-antibiotics? Not by direct assault, but by rebuilding the ecosystem. A rationally designed 7-strain consortium restores the gut's barrier, thanks to one keystone synergist that unlocks the entire team's potential.
Every clinician knows the trade-off. A course of broad-spectrum antibiotics can be life-saving, but it often leaves the gut microbiome a cleared landscape. This state of (sidenote:
Dysbiosis
An imbalance in the microbial community, characterized by reduced beneficial bacteria and increased harmful species, potentially leading to adverse health outcomes.
) opens the door for colonization by antibiotic-resistant bacteria, chief among them vancomycin-resistant enterococci (VRE). A new study from INRAe details a precise strategy to rebuild the gut's defenses, not with a sledgehammer, but with a scalpel.
A precision toolkit for microbiota restoration
Rather than relying on the undefined mix of a fecal transplant, researchers used mathematical modeling to rationally design a consortium of seven specific (sidenote:
Commensal bacteria
Bacteria that cohabit peacefully with their host, particularly in the gut. They can benefit the host by boosting the immune system, aiding digestion, or fighting pathogens.
). This (sidenote:
Live Biotherapeutic Product (LBP)
Biological product containing living microorganisms, such as bacteria, and intended to prevent or treat disorders and diseases (vaccines do not fall into this category).
Rouanet A, Bolca S, Bru A, et al. Live Biotherapeutic Products, A Road Map for Safety Assessment. Front Med (Lausanne). 2020;7:237.
), named Mix7, includes strains from the Lachnospiraceae, Ruminococcaceae, Lactobacillaceae, and Muribaculaceae families. When given to mice challenged with Enterococcus, Mix7 didn't just compete for space; it actively accelerated microbiota restoration. The data shows a rapid recovery of the Bacteroidota phylum, a key group often depleted by antibiotics, which correlates with reduced VRE levels.
Interestingly, the researchers found that the effect of Mix7 was not simply a sum of its parts. When they removed one specific member, (sidenote:
Muribaculum intestinale
A species of anaerobic bacteria belonging to the Muribaculaceae family, a common and abundant member of the healthy mouse gut microbiota. This specific strain was identified in the study as a keystone synergist, essential for the protective effect of the Mix7 consortium
), from the consortium, the entire therapeutic effect vanished. Yet, when administered alone, this bacterium was inert against VRE. In-vitro tests confirmed that none of the Mix7 strains, alone or combined, directly inhibit VRE growth. This points to a cooperative mechanism: M. intestinale is not a direct killer but a keystone synergist, required to enable the other six strains to effectively rebuild the (sidenote:
Ecological Barrier
The protective effect exerted by a healthy and diverse gut microbiota that prevents colonization by invading pathogens. This defense is achieved through mechanisms like competition for nutrients and the production of antimicrobial compounds.
). This is not direct warfare; it's ecological engineering.
This ecological restoration had profound functional consequences. The study found that Mix7 was effective even in a more persistent state of dysbiosis, though not in all subjects, with a 30% to 70% response rate across trials. In "responder" mice, VRE clearance was associated with a complete functional reboot of the gut, marked by higher cecal concentrations of short-chain fatty acids like acetate, propionate, and butyrate, alongside a normalization of bile acid and amino acid profiles.
This variability suggests a powerful clinical application: the initial composition of a patient’s microbiota could serve as a predictive biomarker, allowing for the stratification of patients most likely to benefit from this intervention.
The path from bench to bedside appears promising. Critically for translation, five of the seven bacterial species in Mix7 are shared between mice and humans, with the other two possessing direct human functional equivalents. This work provides a clear blueprint for developing targeted biotherapeutics that not only clear a specific pathogen but also restore the host's endogenous defenses. Such strategies represent a vital new front in the fight against antibiotic-resistant bacteria, a key goal highlighted each year during World Antimicrobial Awareness Week (WAAW).
Each year, since 2015, the WHO organizes the World AMR Awareness Week (WAAW), which aims to increase awareness of global antimicrobial resistance. Held on 18-24 November, this campaign encourages the general public, healthcare professionals and decision-makers to use antimicrobials carefully, to prevent the further emergence of antimicrobial resistance.
Understand the risks of antibiotic resistance in just 15 minutes! That’s the challenge proposed by the Biocodex Microbiota Institute with its first interactive digital fresco, designed to raise broad awareness about this global threat.
It’s a silent pandemic that grows every year and could become, by 2050, the leading cause of death worldwide, ahead of cancer. Antimicrobial resistance is under the spotlight of the World Health Organization, which has organized the World Antimicrobial Awareness Week every year since 2015. This initiative aims to raise awareness and improve understanding of antimicrobial resistance, while also promoting coordinated actions to combat the emergence and spread of drug-resistant pathogens.
A cornerstone of scientific information and a key player in educating and training healthcare professionals and the general public on the importance of human microbiota, the Biocodex Microbiota Institute is taking part in this campaign for the sixth consecutive year by offering its audiences an educational, engaging, and interactive workshop: the first awareness mural on antibiotic resistance.
15 minutes to grasp the urgency and take action
Primarily intended for healthcare professionals (general practitioners, pharmacists, pediatricians, hospital staff, and healthcare students), the workshop is designed to be simple, visual, and participatory. It takes the form of a game with 60 cards that allow participants to reconstruct different antibiotic use scenarios and assess their consequences on multiple levels:
The workshop then invites participants to take a step back and reflect on the global risks associated with antibiotic resistance (increasing deaths, pressure on research, and the potential return to a “post-antibiotic era”). Finally, it concludes on a positive note, focusing on concrete, multi-stakeholder solutions: prevention, vaccination, research, responsible prescribing, and the One Health approach. And for the first time, this tool is freely available accessible and downloadable by everyone.
A ready-to-use tool accessible to everyone
Developed in partnership with Querceo, the workshop was designed to be easy to implement:
Short duration (15 minutes) and a format adaptable to groups of around ten participants
Can be used during medical congresses, hospital meetings, university courses, or public events.
Nearly 3 out of 4 people now know that antibiotics have an impact on their microbiota (73%, +4 points vs 2023). However, only 2 out of 5 patients report having received information from a healthcare professional about these effects (39%), and barely 38% say they were advised on how to limit the consequences.
“These figures reveal a concerning gap: while public awareness is growing, medical guidance on antibiotics remains insufficient.
This interactive and educational workshop is not meant to replace the information provided by healthcare professionals, but rather to offer an additional way of understanding the issue. Its goal is clear: to strengthen dialogue between healthcare providers and patients, and to raise broader public awareness of this major health challenge one that shapes today’s medicine and will determine the health of future generations.”
Olivier Valcke, Director of the Biocodex Microbiota Institute
About the Biocodex Microbiota Institute
The Biocodex Microbiota Institute is an international knowledge hub dedicated to human microbiota. The Institute communicates with its users in seven languages, targeting both healthcare professionals and the general public with the aim of raising awareness about the vital role this organ plays in our health. The Biocodex Microbiota Institute’s primary mission is educational: to spread the word about the importance of microbiota for everyone.
About Querceo
Querceo is a consulting firm that takes a collaborative and systemic approach to supporting organizations through the ecological transition. By creating and disseminating awareness-raising workshops, such as the Biodiversity Mural, the One Health Mural, or the SiNergie workshop, Querceo helps mobilize organizations, enabling each individual to understand and take ownership of the major challenges of tomorrow.
Antimicrobial resistance (AMR) threatens the effectiveness of healthcare. It is time to take action: this page provides you with practical tools to equip yourself and raise awareness among your patients about this global issue.
Antibiotics have revolutionized modern medicine, saving countless lives. However, their repeated or inappropriate use profoundly disrupts the gut microbiota, reducing its diversity and protective capacity. This dual aspect of therapeutic progress and microbial imbalance highlights the need for judicious use.
70 %
of people claim to know that antibiotics impact the microbiome
35 %
Only 1 in 3 people had been informed by a HCP that taking antibiotics could have negative consequences on the balance of their microbiota
To mark the WHO's annual World AMR Awareness Week, The Biocodex Microbiota Institute takes stock.
What is the World AMR Awareness Week?
Each year, since 2015, the WHO organizes the World AMR Awareness Week (WAAW), which aims to increase awareness of global antimicrobial resistance.
Held on 18-24 November, this campaign encourages the general public, healthcare professionals and decision-makers to use antibiotics, antivirals, antifungals and antiparasitics carefully, to prevent the further emergence of antimicrobial resistance.
Dysbiosis: effects of antibiotics on health and microbiota
Repeated exposure to antibiotics can profoundly disrupt the balance of the microbiota, leading to dysbiosis with various clinical consequences. These alterations in the microbiota are now recognized as a risk factor in many diseases. Better understanding them means strengthening prevention and personalizing care.
Antimicrobial resistance: a serious threat for human health
The widespread and sometimes inappropriate use of antibiotics is making them less and less effective in treating infections, with many bacteria now resistant to antibiotics. Surveillance, research, and awareness remain essential to controlling this major health issue.
Microbiotalk: short conferences on antimicrobial resistance
This Microbiotalk conference aims to illuminate the multifaceted challenges of AMR, exploring the intricate connections between gut microbiota, environmental factors, and public health. Featuring international experts and patient advocates, the event delves into topics such as the impact of antibiotics on the intestinal microbiota, the emergence of resistance in early childhood, environmental reservoirs of resistant bacteria, and the critical role of patient and public engagement.
Antimicrobial resistance fresco: learn, play and act now
Every initiative counts in the fight against antimicrobial resistance. Visualizing data, sharing knowledge, and strengthening collaboration among healthcare professionals are essential levers. Collective awareness is at the heart of the global prevention strategy.
Discover the first collage illustrating the challenges of antimicrobial resistance.
After antibiotic treatment, the microbiota takes time to regain its balance. Approaches based on understanding the interactions between antibiotics and intestinal flora are paving the way for new support strategies. This knowledge opens up promising prospects for maintaining a healthy microbiota and preventing post-treatment dysbiosis.
How to rebuild my gut microbiota after taking antibiotics?
How to talk about gut health: Pr. Sokol's advices. This educational video series is designed to help healthcare professionals better communicate with their patients about gut microbiota
The effects of antibiotic resistance extend beyond the clinical sphere: they also affect the environment, the microbiota, and global health. This global phenomenon requires an integrated “one health” approach to be effective. Now is the time for understanding, prevention, and collaboration.
Check out our articles to explore the full range of impacts of resistance and the solutions being considered on a global scale:
A Chinese research team has recently identified a bacterium in the gut microbiota that may be involved in chemotherapy resistance in patients with colorectal cancer. They have also identified a phage capable of specifically targeting this bacterium and restoring tumor sensitivity to treatment.
Will phages (viruses that target bacteria) soon be part of the therapeutic arsenal for fighting colorectal cancer (CRC)? So suggests a fascinating study published in the journal Cell Host & Microbe. 1
According to the authors, a gut bacterium found in abundance in those who fail to respond to treatment may be responsible for resistance to chemotherapy. Eradicating this bacterium with phages may make it possible to restore the sensitivity of cancer cells to treatment and thus improve patient survival.
To show this, the researchers went through several stages. First, based on the analysis of the microbiota of two independent cohorts of patients (a total of 106 patients, 34 of whom did not respond to treatment), they noticed that the abundance of the bacterium Bacteroides fragilis was significantly higher in non-responders, and that this abundance was correlated with a poorer prognosis.
1.9 million
The number of new cases of colorectal cancer worldwide in 2020. ²
930,000
The number of deaths related to colorectal cancer in 2020. ²
A gut bacterium that worsens prognosis
The scientists asked whether B. fragilis was responsible for chemoresistance. To test their hypothesis, they cultured human cancer cells in the presence of B. fragilis and then with two chemotherapy drugs, 5-fluorouracil (5-FU) and oxaliplatin (OXA).
The results indicated that B. fragilis does indeed reduce the sensitivity of cancer cells to chemotherapy, in particular by suppressing chemotherapy-induced apoptosis. These results were confirmed in vivo in the same experiment on mouse models of CRC, with a greater number of tumors present in mice exposed to B. fragilis than in those not exposed, following treatment with 5-FU and OXA.
An RNA analysis of the cells co-cultured with or without B. fragilis and then treated with 5-FU and OXA showed that B. fragilis upregulates the Notch1 metabolic pathway that appears to underlie the chemoresistance of CRC cells.
The researchers then asked what interactions between the bacteria and cancer cells activated the Notch1 pathway. Using scanning electron microscopy of cells in vitro and in vivo, they observed that B. fragilis did indeed adhere to cancer cells.
According to the authors, on the surface of the bacteria there is a membrane lipoprotein from the SusD/RagB family that is capable of binding specifically to Notch1 receptors on cancer cells. This binding activates the Notch1 signaling pathway and induces the “epithelial-to-mesenchymal transition”, which corresponds to the first stage of cancer cell dissemination (metastases).
3rd most common
type of cancer. ²
2nd most common
cause of cancer-related death. ²
People over 50
are the most affected. ²
Phages to the rescue
To cap off the study, the researchers identified a phage called VA7 that is capable of specifically eliminating B. fragilis safely and effectively. They administered the VA7 phage to CRC mice that had become chemoresistant following exposure to B. fragilis and found that it completely reversed the induced chemoresistance.
This study is particularly interesting because it shows that:
An abundance of B. fragilis in the microbiota of CRC patients could serve as a non-invasive biomarker to predict the effectiveness of chemotherapy.
Combining chemotherapy with VA7 phages in patients with an abundance of B. fragilis could improve clinical response without side effects.
To be continued...
B. fragilis is not the only bacterium that influences the prognosis of colon cancer
According to French researchers, colibactin-producing Escherichia coli (a genotoxic and protumor substance) is also present in abundance in certain colorectal cancers, particularly right-sided colon cancer. 3 This bacterium makes cancer cells less visible to the antitumor immune system and less sensitive to the action of chemotherapy. In 2019, a Chinese study 4 showed that Fusobacterium nucleatum also reduced the effectiveness of 5-fluorouracil.
A super simple way to improve your lifestyle is to eat almonds daily. According to a new study, if you have an unbalanced diet, snacking on these nuts may have a very positive impact on your gut flora and overall health.
Concerned about your health but find it difficult to eat healthily? Need to lose weight but suffer from cravings? Try replacing cereal bars, cookies, and other fatty, sugary, and salty snacks with almonds. A study conducted by researchers at Florida State University 1 in the United States suggests your gut microbiota would benefit greatly, and so would your health.
People who eat a Western diet often suffer from dysbiosis, while being overweight generally leads to gut imbalances. To find out whether almonds could help remedy this, the scientists recruited 15 overweight or obese adults and divided them into two groups:
The first group followed a “typical” American diet (high in fat, carbohydrates, meat, processed foods, etc.)
The second followed the same diet, but supplemented with 42.5 g of almonds per day (two small handfuls, or about 30 almonds).
After four weeks, all participants returned to a normal diet for 15 days, then switched diets for another four weeks.
The researchers took stool and blood samples to analyze changes in gut microbiota composition and bacterial metabolites, as well as various health markers.
The results showed that snacking on almonds enriches the gut microbiota with beneficial bacteria and suppresses pathogenic microorganisms.
Furthermore, these changes are correlated with clear improvements in certain health markers.
By supporting the proliferation of Faecalibacterium prausnitzii, a well-known beneficial bacterium that produces butyrate (a short-chain fatty acid, (sidenote:
Short chain fatty acids (SCFA)
Short chain fatty acids (SCFA) are a source of energy (fuel) for an individual’s cells. They interact with the immune system and are involved in communication between the intestine and the brain.
Silva YP, Bernardi A, Frozza RL. The Role of Short-Chain Fatty Acids From Gut Microbiota in Gut-Brain Communication. Front Endocrinol (Lausanne). 2020;11:25.)), almonds could strengthen the intestinal barrier, reduce inflammation, and promote cardiovascular health.
By reducing the abundance of pathogenic bacteria such as Ruminococcus torques, these nuts could lead to a health-beneficial reorganization of the microbiota’s ecological niche.
Almonds may slow cellular aging.
Two large handfuls of almonds (60 g per day) may protect cells from oxidative damage while strengthening the body’s antioxidant defenses. So say scientists who compiled the results of eight clinical trials on the antioxidant effects of almonds. 2 However, to fully benefit from these effects, almonds should be eaten “plain,” i.e., unpeeled, unroasted, and unsalted.
Likely to affect weight and satiety
Almond consumption may also lead to a decrease in certain toxic bile compounds associated with intestinal diseases, particularly colon cancer, and an increase in ketone body levels.
Ketone bodies are molecules produced by the digestion of body fat. The increase in these bodies during the experiment may be linked to the satiating effect of almonds, which encourages the body to use its fat reserves as a source of energy more often.
Lastly, almond consumption was associated with an increase in the levels of two hormones, GLP-1 and YY, which play a role in hunger control, insulin sensitivity, and blood sugar control after meals.
According to the researchers, “daily almond snacking not only helps maintain gut homeostasis but also may alter the metabolic state and improve metabolic health.”
Keep this in mind the next time you go grocery shopping.
Could lactobacilli, the guardians of vaginal health, also boost the chances of getting pregnant after a frozen embryo transfer? This is suggested by a US study 1 that also links this trend to ethnic origin.
When talking about (sidenote:
Infertility
Disorder of the male or female reproductive system defined by the inability to achieve pregnancy after 12 months or more of regular unprotected sexual intercourse.
https://www.who.int/news-room/fact-sheets/detail/infertility ) and ART (assisted reproductive technology), we often think of a journey filled with hope, expectation... and sometimes disappointment. Among the proposed techniques, frozen embryo transfer consists of placing in the uterus an embryo previously conceived in the laboratory through (sidenote:
In vitro fertilization (IVF)
A medical assistance technique for procreation where fertilization takes place in the laboratory, in a test tube (“in vitro”), and not in the woman’s uterus: eggs retrieved from the woman after hormonal stimulation are placed in a nutrient solution with sperm collected from the man. The embryos thus conceived in the laboratory will then be transferred to the future mother’s uterus via the vagina. If an embryo implants, the pregnancy begins.
https://www.service-public.fr/particuliers/vosdroits/F31462 https://medclinics.com/fr/fiv/ https://www.fiv.fr/fecondation-fiv/), then frozen and subsequently transferred.
17,5 %
Infertility is common worldwide, with a lifetime prevalence estimated at 17.5%.
The aim? To achieve embryo implantation, thus initiating the eagerly awaited pregnancy. However, in reality, it’s not automatic: only 41% of egg retrievals result in pregnancy in women under 35.
+52% pregnancies with Lactobacilli
In this context, every little bit helps. And it seems that help might come from the microbiota, already involved in female and male infertility and in miscarriages. Could it also promote embryo implantation in cases of ART? A study conducted in the United States focused on 87 women who underwent frozen embryo transfer. It analyzed their vaginal microbiota at the time of transfer to see if it influenced the outcomes.
Did you know ?
Although in vitro fertilization (IVF) success rates have gradually improved, the rate of live births per egg retrieval remains around 41% for women under 35 and progressively decreases with maternal age.
Result: among women whose vaginas were largely dominated by lactobacilli, particularly Lactobacillus crispatus or L. gasseri species, chances of pregnancy were 52% higher! Two-thirds of the women who became pregnant after embryo transfer had more than 80% lactobacilli in their vaginas.
Conversely, women whose microbiota hosted more opportunistic bacteria like Enterobacteriaceae or Streptococcus were less likely to become pregnant. However, neither the richness nor the diversity of the flora was associated with ART success: it is the type of bacteria that makes the difference.
Another interesting point addressed by the study: ethnic disparities. The authors made sure to include Hispanic women, who represent 19% of the US population but are often missing from studies.
The results show they had lower pregnancy rates. And their vaginal microbiota is less often dominated by beneficial Lactobacillus compared with non-Hispanic white women. A link worth exploring, which could partly explain lower rates of successful frozen embryo transfer in the Hispanic community.
Inflammatory Bowel Disease (IBD) and microplastics: an explosive cocktail?
Microplastics: beware of takeaway food packaging and their impact on the microbiota!
