Microbiotalk: "Break barriers and address taboos in women’s health" - 2026

Breaking down barriers: a bold conversation about women’s health. From puberty to conditions such as endometriosis, international experts share the latest scientific advances. The goal: to better understand the interactions between the microbiome, hormones, and health throughout a woman’s life, by breaking down the taboos that still surround these critical topics.

The vaginal microbiota

Despite growing scientific interest, many aspects of women’s health remain surrounded by taboos and knowledge gaps. Hosted by the Biocodex Microbiota Institute, this Microbiotalk 2026 edition aims to deepen understanding of the microbiome’s role across a woman’s life from puberty to conditions such as endometriosis.

Bringing together leading experts, including Prof. Ina Schuppe Koistinen and Prof. Andrew Horne, the event explores key topics such as the development of the vaginal microbiota during puberty and the current challenges in understanding endometriosis and its links with the microbiome.

By addressing these questions, these exchanges contribute to advancing scientific knowledge, improving awareness, and fostering more open discussions around women’s health.

Prof. Ina Schuppe Koistinen

First periods & discovering the intimate ecosystem balance

Image

“Microbiota is like an inner pharmacy, which is producing lots of components that are essential for our health.”

Prof. Ina Schuppe Koistinen's biography

Ina Schuppe Koistinen, PhD is a microbiome researcher, Associate Professor affiliated with Karolinska Institutet, and innovation strategist specializing in microbe–host interactions and their role in women’s health, fertility, and healthy aging. Her research explores how microbial ecosystems influence inflammation, reproductive function, epithelial barrier integrity, and long-term health trajectories.

She is the founder of Beyond Oneness Consulting, advising biotech, medtech, and pharmaceutical companies on translating microbiome science into clinically and commercially viable interventions. Ina has co-founded and led a deep-tech biotech startup developing microbiome-based therapies and has contributed to the clinical and regulatory development of antibiotic-free approaches to treating vaginal dysbiosis.

Her work bridges microbial ecology and translational medicine to harness beneficial microbes to improve reproductive health, extend healthspan, and prevent chronic inflammatory conditions. In addition to her scientific work, she is the author of the popular science book Vulva: Facts, Myths, and Life-Changing Insights and an accomplished visual artist whose work explores the intersection of biology and human experience.

Prof. Ina Schuppe Koistinen's speech

A crash course on the microbiome

So I start with a little crash course on the microbiome. So what is it we actually are talking about?

But maybe you have never thought about that, but humans actually never existed without microbes. They were on the world long before us and we developed in total symbiosis with microbes. That means bacteria, viruses, archaea and other small, small, one single celled organisms in our bodies, in and on our bodies.

So we have about 200 or 20,000 human genes and maybe up to two, 20 million microbial genes. So that means they really outnumber us. And it's like an inner pharmacy, which is producing lots of components that are essential for our health.

And the best thing about it, we actually have a possibility to influence it.

  • We can't change our genes.
  • We are born with them.
  • But we actually can change our microbiome by our lifestyle choices, our diet choices, and many other things I'm going to talk about.

The gut microbiome

The microbiome that is studied most is the one we have in our gut. And in the gut, we have about 1.5kg of microbes, which is a huge number. It's almost like the weight of our brain.

One thing is that we think about the gut microbiome. The more diverse, the more different species, the healthier we are. And we also are very individual. So we overlap in maybe 99.9% of our genes. But in the microbiome we only overlap like one third. So you have a very individual signature.

And the microbiome in the gut affects actually all parts of the body.

  • It affects our skin
  • It affects our brain
  • Other organs
  • And also the vagina

How the microbiome is established

So when we are born we are seeded with the microbes of our mothers. So we call that a vertical transmission.

And there are differences. If you are born with, vaginal delivery or are born with a C-section, but these differences are kind of going away within the 2 to 3 years of age.

And there are many, many sources to get colonized by microbes, by breast milk, for instance, that contains up to 200 different species of lactobacilli and Bifidobacteria, which are essential for the health of the baby.

But then you have kind of keep a relatively stable microbiome for many years of your life, unless you use antibiotics or affected by very severe infections.

Factors that influence the microbiome

But there are many other factors that influence like our lifestyle and our age.

Also:

  • If we live in close nature
  • In close relation to nature
  • To animals
  • And how big the families are

The vaginal microbiome and good health

And, when we think about the vaginal microbiome, then we can say that a microbiome that is dominated by lactobacilli is the one that is associated with good health. So it's different from from the gut.

But these lactobacilli are like the superheros of the vagina because they reduce the pH and by that prevent infection or growth of other bacteria or pathogens.

They also produce other antimicrobial components, such as hydrogen peroxide or bacteriocins that are small peptides that kill off bacteria. They are very kind of adherent to the epithelium or to the layer of the vagina and also have a very close interplay with the immune system.

Changes across life stages

So the vagina microbiome changes during the life course of a woman or a girl.

At birth and during childhood

So when the baby girl is born, the girl or still have the estrogen or the female sex hormone levels of the mother in her blood. And, since the microbiome is very much influenced by estrogen levels. So this will help the girl to establish a microbiome in the vagina that is dominated by lactobacilli.

But since the girl is not able to produce their own estrogen yet, it the microbiome will get more diverse, during childhood.

Puberty and fertile life

But then during puberty and the estrogen levels rise, this microbiome is reestablished with lots of lactobacilli. And that is a good thing.

And that will be kept through the entire fertile life of a woman and also during pregnancy with increasing estrogen levels, the microbiome gets more beneficial and more stable, and that also contributes to healthy pregnancies and less complications.

Menopause

During the menopause or prior to menopause. And after that, then the levels decrease and also the microbiome gets more diverse.

Other factors influencing the vaginal microbiome

There are also other factors than just estrogen that influence the microbiome.

The gut microbiome

It is the gut microbiome. Because the bacteria in the vagina are originally seeded from the gut. We don't understand today the precise mechanisms, how the immune system supports the transfer to the vagina.

But the healthy gut microbiome is important, and a healthy gut microbiome is influenced by our diet. So that is very important.

Menstruation

Menstruation per se is important because if you have blood in the vagina, then the pH level will increase because blood has a neutral pH of seven, and also the nutrients for the bacteria will change. And that is not in favor of lactobacilli.

Pregnancy

Pregnancy influences as I already mentioned.

Sexual intercourse

Sexual intercourse influences the same reason as for menstrual blood. The change of pH and also different nutrients are added to the vaginal environment if you have unprotected sex.

Lifestyle and hygiene

Lifestyle and hygiene is very important.

So my recommendation is always:

  • Just to wash your intimate places with lukewarm water
  • Maybe a specific mild soap
  • And not use any perfumes or any harsh detergents
  • And especially not using any of these vaginal douching techniques where it's a lot of advertisement for

Diseases and drugs

And diseases and drugs to influence the microbiome as well.

Risks linked to low lactobacilli levels

So women that are deficient of lactobacilli in the vagina are at higher risk for reproductive diseases. And also adverse obstetric outcomes. And that's why this is so important.

And that's why this is so important for young girls like Camille to understand that we have to take care of our microbiome, support it in the best way.

So we are protected from:

  • Infections
  • Reduced fertility or difficulty getting pregnant
  • Pregnancy complications
  • Pelvic inflammatory diseases
  • The malignancies that would come with HPV infections for instance
  • Urinary tract infections

Microbiome dynamics during menstruation

So during the menstruation, we have studied in detail how the microbiome shifts and what the dynamics are.

And this is from a recent publication of our lab where we could show in blue, lactobacilli in the vagina. And then there are samples from individual women. Each day during the menstrual cycle, you can see that a big proportion of women, they have a stable microbiome with lactobacilli.

But there is also a proportion that has:

  • Dysbiosis
  • Or, kind of a shift to more pathogenic bacteria during bleeding
  • So during menses
  • And there are others that have a dysbiotic microbiome, during the whole period

So it is very important to understand those dynamics and fluctuations, especially when you do assign drugs and treatments, because the microbiome is not a static environment.

Take-home messages

So my take home message here is:

  • Remember we are ecosystems.
  • The microbiome is a key driver of our health and longevity.
  • The gut and vaginal microbiomes do regulate immunity, metabolism and the barrier function.
  • And that's why they are so important for our health.
  • An imbalance of the microbiome thus fuel inflammation, disease risk, and also accelerated aging.
  • We have a chance to influence our microbiome by lifestyle choices, but it's also formed by hormone levels and the environment we live in.
  • The best support for the microbiome is a diet that is rich in vegetables and dietary fibers, and also in fermented foods that support our microbiota.
  • And the vagina, per se is an amazing organ.
  • It actually cleans and protects itself through natural discharge and a balanced vaginal microbiota.
  • So it's important for all of us to take good care of it.
Prof. Ina Schuppe Koistinen's answers (Q&A sessions)

Question n°1

In the assembly, there's a lot of parents of teenagers and also behind the screen, and we would like to know from your point of view, what are the most important message, parents and teenagers should know about the microbial microbiome at puberty? 

Expert's answer

I think the most important message is that girls should be aware of the discharge. And that discharge changes during your tween puberty. And also not kind of, washing with very strong detergents and destroying the microbiome. So the best is really to let the vagina do the job herself because of the discharge, it's cleanses. And if we destroy the environment with perfumes or products that kind of, designed to put shame on female bodies, we will just, kind of destroy that balance. So be aware of treating it gently and keep the balance. 


Question n°2 

And you talk about the discharge and the maybe order, but how can we help, a teenage girl to understand what is “normal” versus when they should consult, a doctor?

Expert's answer

Yeah, this is very difficult. And I think it's general, as you also put on your original slide here, breaking taboos because we don't talk about it, but we need to talk about it because if we don't teach our daughters what is normal, how should they know? And in general it is if there is a very, very strong odor, if there is itching or some other symptoms that are disturbing, then you should see a doctor and not just wash more, use more soap and all these things that are kind of intuitive but are counterproductive for the microbiome.


Question n°3

And so if you have to give 1 or 2 simple tips to help protect the microbiome during adolescence, what would they be?

Expert's answer

Yeah, I already mentioned the tips. Yeah. To avoid perfumes and soaps I think that's the most important. And also just to not to be ashamed. Yeah. And and just to see it as a natural part of your body and don't believe in all this rubbish that is on social media that your vagina should smell like pineapple, that I mean, there is so much misinformation out there. Don't believe it.


Question n°4

And then you mentioned in your talk that, there's a lot of factors influencing the the vaginal microbiota. How do hormones and first period shape the microbiota is it like, a balance ? What's happens?

Expert's answer

I mean, during puberty, the, estrogen levels or the female sex hormone levels in blood increase and that estrogen makes that the cells that line the vagina produce more glycogen. And glycogen is a nutrient for, for lactobacilli. So they are kind of the biology is designed to make lactobacilli grow to protect the vagina. And that's a natural process. And we should just kind of leave it there.

3 key messages

  • Humans function as ecosystems, where the gut and vaginal microbiomes play a central role in regulating immunity, metabolism, and protective barriers that influence overall health.

  • Microbial balance is continuously shaped by hormones, lifestyle, and environmental factors, and imbalances can contribute to inflammation and increased disease risk.

  • Supporting microbiota from early life through healthy habits such as a diverse, fiber-rich diet is important, while the vagina naturally maintains protection and balance through its own microbiota.

Download her presentation

Prof. Andrew Horne

Endometriosis: understanding better to break taboos & take action

Image

“And whilst there are, larger studies emerging, we don't have a consistent, if you like, endometriosis microbiome pattern as yet.”

Prof. Andrew Horne's biography

Professor of Gynaecology and Reproductive Sciences at the University of Edinburgh, Prof. Horne is Director of the Centre for Reproductive Health and Honorary Consultant Gynaecologist at NHS Lothian. A leading expert in endometriosis and pelvic pain, he has published over 200 peer-reviewed articles. He serves as President of the World Endometriosis Society, Trustee to Endometriosis UK, and Specialty Advisor to the Chief Medical Officer of Scotland for Obstetrics and Gynaecology.

Prof. Andrew Horne's speech

Endometriosis: definition and prevalence

So I hope, everyone here has heard of endometriosis, particularly, because this is Endometriosis Awareness Month. But I think particularly because this is a really common condition, it's said to affect, 1 in 10 women and those assigned female at birth. That's the equivalent of an estimated 190 million individuals worldwide.

Endometriosis is a condition that's defined by the presence of tissue, like the lining of the womb, outside of the womb, outside of the uterus, and that tissue can be found almost anywhere within the body, can be found within under the diaphragm. It can be found on the umbilicus. It can even be found within the lung.


Main pelvic subtypes

But the commonest site for endometriosis is within the pelvis, and there are three, pelvic subtypes.

  • The commonest, which accounts for around 80% of the disease that we see is called a superficial peritoneal endometriosis. This is when you get, diffuse endometriosis lesions around the pelvic sidewall.
  • Endometriosis can also exist as a ovarian disease. This is a cystic form of endometriosis, often called “chocolate cysts” because they have altered blood inside them. And these cysts appear on the ovaries.
  • Or you can choose this as a deep disease. And deep disease is a more fibrotic and nodular disease that often involves the bowel or the bladder


Symptoms and associated conditions

The endometriosis can cause a large number of different symptoms. Probably the most recognized are painful symptoms.

  • Painful periods are often very severe and debilitating.
  • Pain outside of periods.
  • Pain with sex.
  • Pain with menstruation.
  • Pain on defecation.

But it can also, cause a range of other symptoms such as diarrhea and constipation, other urinary symptoms, fatigue, depression, and around a third of people who experience endometriosis, suffer from infertility, difficulty getting pregnant.

It's also associated with other gynecological conditions out adenomyosis and fibroids. Is associated with other chronic pain conditions, other inflammatory conditions, and in later life, it can put people at greater risk of conditions like cardiovascular disease and also certain types of cancer.

Diagnostic approaches

Endometriosis is diagnosed using a number of different, approaches, a history and examination, is important. Imaging is important. And laparoscopy or keyhole surgery, is often necessary. And this is carried out under a general anesthetic to try and visualize the disease and often take, a biopsy of the disease.

And there are a number of emerging tests which hope to supersede, the invasive nature of a laparoscopy. Both saliva and blood in particular, have been studied.


Limits of current diagnosis

But one of the problems, with the endometriosis, diagnosis is that none of these approaches are particularly effective.

So, for example:

  • a clinical history, an examination isn't able to differentiate between the three subtypes of Endometriosis that you can see here.
  • Imaging is only effective for ovarian and deep disease and isn't effective to detect superficial peritoneal disease.
  • Surgery, of course, is dictated by, access.
  • They're often, huge waiting times for patients to have surgery.
  • Even with a laparoscopy, sometimes disease can be unrecognized or microscopic disease can be difficult to pick up.

The biopsy, is also not always helpful. It can be complicated by artifacts, and around 50% of biopsies taken for Endometriosis don’t confirm the disease.

I know whilst there's been a lot of work looking at different, biomarkers, sadly none of these have been, validated in such that they can be, brought into clinical practice, at present.


The diagnostic journey

So patients with Endometriosis often have this awful, prolonged diagnostic journey estimated to be around, eight years in most countries across the world.

So they might:

  • See multiple different, healthcare professionals in the primary care setting
  • Perhaps go to accidents and emergency and casualty departments
  • Before they actually see a specialist, a gynecologist.

And even when they see a gynecologist, they might have to undergo multiple, imaging tests. They might see other specialties, before they have a definitive diagnosis. And importantly, before they're given appropriate treatment for the condition.


Treatment approaches

So how is endometriosis diagnosed? Well, it can be diagnosed in a disease specific way if you like. And that can be either by surgery and this is laparoscopic or keyhole surgery to remove, the lesions. Or it can be treated with a range of different hormone treatments.

And the rationale for using hormones is: we know that Endometriosis is an estrogen dependent condition. And if you give hormones that suppress, ovarian, estrogen production, it's been shown to help with this, the painful symptoms associated with the condition.

And alongside that, we often, offer pain management strategies, non-steroidal anti-inflammatory neuromodulator drugs like nortriptyline and pregabalin, and then complementary therapy, if you like, like physiotherapy, psychological, treatments. And then patients themselves often use things like tense machines, heat and cool packs and dietary changes, which I'll talk about in a minute.


Surgery

So let's look, first of all, at surgery for Endometriosis.

Well, the surgery, although it's performed laparoscopically can be either performed by excision or ablation with, for example, late, lace or heat. And there's a huge amount of debate, particularly across the internet, about which of these approaches, is better. And fortunately, at the moment we don't have any evidence for one, above the other.

The other problem with, surgery is of course, it carries risks.

  • You have to have a general anesthetic
  • Then there's a risk of complications at the time of surgery
  • The surgery itself can even put patients at risk of developing, chronic post, surgical pain.

The other problem is that surgery, isn’t  a cure for endometriosis, around 30% of patients experience no benefit. And then their high recurrence rates of up to 50%, within five years.


Hormone treatments

What about, hormone treatments for Endometriosis?

Well, there are range of different hormone treatments that can be used. And these includes combined contraceptives, progestin and GnRH agonists and antagonists. And they can be given by a range of different approaches.

But:

  • There isn't one particular hormone that said to be more effective than the other.
  • They're only effective when they're being taken.
  • They all have a range of different, side effects.
  • They’re all contraceptive.

And this is often a young population of women who are maybe wanting to have a family and don't want to take something which is not, fertility sparing.

We carried out a survey of patients across the UK, just over, 1500 patients, responded to this survey asking them about these hormone treatments. And this is the word cloud from the question that we asked them: which hormone or medication helped most. And you can see that whilst there is a large number of different, treatments, there isn't one treatment that comes to the fore. And in fact, the evidence would suggest that current hormone treatment leaves about 50% of patients with persistent or recurrent pain.


Self-management and diet

So it's perhaps not surprising that, patients, turn to other treatment strategies, strategy self-management strategies, such as changing their diet.

And we carried out another survey just three years ago now of just under 3000 individuals with Endometriosis across the globe. And you can see that they use a different, number of approaches, in terms of removing things from their diet, perhaps not surprisingly, things like alcohol and, caffeine, processed sugar, ultra processed foods.

And you can see that and these approaches did appear to have an impact upon reducing some of their painful symptoms.


Gut microbiome research

And so, perhaps not surprisingly, there has been a move to look, at gut bacteria in the microbiome. and endometriosis.

So if we look at what, studies have been performed to date, first of all, focusing on animal studies, most of these studies, have used models of induced endometriosis. And this is largely because, mice, for example, the commonest animal that is studied don't actually spontaneously develop Endometriosis, says they don't menstruate. So you have to develop a model of mouse menstruation and then, using that model and induce endometriosis.

The other problem with these studies is:

  • They focus largely on disease development and not symptom relief.
  • They also use a wide number of different approaches.
  • So there's little consistency.
  • Whilst there have been some promising, treatments suggested, the studies supporting these have lacked measures of well-being or behavior.

If we look at the human studies, looking at the gut microbiome, there have only been a small number of studies to date, and most of them have involved only small numbers of patients. So they're difficult to generalize.

And again, like the animal studies, they've used a multitude of different, approaches. And whilst there are, larger studies emerging, we don't have a consistent, if you like, endometriosis microbiome pattern as yet.


ENDO 1000 study

But I think things are changing. And one of the studies that we're leading on, in Edinburgh hopes to address this. And this is called the ENDO 1000 study. You can scan the QR codes here if you want to hear a bit more about it and follow the the study on social media.

And with this study, what we're hoping to do is, a recruit a thousand people with endometriosis associate symptoms. And we launched this study. I'm just in January this year. And then we're going to work with them really closely over a period of two years.

They'll record:

  • Their symptoms
  • Any treatments that they have
  • Any changes in their health on our Endo1000 app.

And at the same time, we'll collect, biological samples:

  • Saliva to look at their genetics
  • Blood to look at their inflammatory profile
  • Urine, feces and a vaginal swab to look at their microbiome and their metabolome.

And the idea is that we'll collate all of the information that we collect from the app, from interrogation of these bio samples with data that we'll also collect from a smartwatch, looking at their activity and sleep patterns into this big, resource that we can interrogate to look for patterns that might help, with, another noninvasive, diagnosis, test for endometriosis.

But I think, most importantly, help us identify patterns which can predict the best medical and surgical, and self-management strategies for the condition.

Prof. Andrew Horne's answers (Q&A sessions)

Question n°1

Endometriosis can take years to be diagnosed, but for women, what are the key warning signs that people should look out for?

Expert's answer

So I think one of them is in particular that you've just mentioned is that kind of normalization of pain. So if you have painful symptoms that are interfering with your ability to work or to socialize, it's really important you seek help. In terms of symptoms which might make you think it’s endometriosis: symptoms that have a cyclical pattern so there may be related to the menstrual cycle that can be, a warning sign.


Question n°2

How can someone understand which option might fit them best?

Expert's answer

So it's slightly depends which symptoms are important to them and what point they are in their life course. So if pain is a primary symptom, then they might go for surgery or some hormone treatments. But of course if fertility is an issue for them. Surgery can be helpful for some types of endometriosis, but often patients have to undergo IVF. I'm always very positive about that aspect of the disease if someone is given a first diagnosis, because we have to emphasize that two thirds of people will conceive spontaneously, without any support, if they happen to have endometriosis. So the one third often undergo IVF treatment, which of course is a big undertaking that IVF treatments and patients with endometriosis is generally very successful. So there’s hope.


Question n°3

In your opinion, what would be the next step in research?

Expert's answer

So I think it's it's about, performing these bigger studies a bit a bit like ENDO 1000, to try and actually define the endometriosis microbiome pattern and then obviously look at that pattern. And that pattern might be used, as I say in in diagnosis. But I think more importantly potentially to alleviate the symptoms associated with the condition.


Question n°4

Symptoms sometimes overlap with IBS. In your opinion, could the microbiome be part of the link between the two conditions ?

Expert's answer

Yes. I mean, around 20 to 40% of patients who have an endometriosis diagnosis will also have, irritable bowel syndrome. So there's definitely a link there. And I think the gut microbiome is the most natural place to to look for that link.

3 key messages

  • Only a small number of human studies have investigated the relationship between gut bacteria and endometriosis.

  • Most existing studies involve small, heterogeneous patient groups and use different methods and measurements, making results difficult to compare and limiting the reliability of conclusions.

  • Current research has not yet identified a consistent gut microbiome signature associated with endometriosis, although a few larger studies are beginning to emerge.

Download his presentation

Microbiotalk: "Break barriers and address taboos in women’s health" - 2025

Discover our previous edition

What women know(and don't know) about their vaginal microbiota

Explore our 2025 observatory results

Disclaimer: these exchanges took place in English and were translated into other languages using artificial intelligence. 

Summary
Off
Sidebar
Off
Migrated content
Désactivé
Updated content
Désactivé
Hide image
Off
Article Off

When your beauty routine kills certain bacteria

The use of moisturizers and sunscreens is associated with changes in the skin microbiota that lives on the surface of your skin and contributes to its health.

The skin microbiota

The skin is a vital barrier: it protects our bodies from the sun's harmful ultraviolet rays, various chemicals we come into contact with, and microorganisms we encounter. To help it perform this task, it hosts skin microbiota, a collection of microorganisms that play a key role in our immunity. But what effect do the moisturizers and sunscreens we regularly apply to this tiny world have?
To identify and understand the influence of these routines on our skin microbiota and skin health, a team of researchers studied the faces of 10 men and 27 women1.

Your beauty routine changes your microbiota

When it comes to skin, we all have things in common (such as hosting bacteria like Cutibacterium acnes and Staphylococcus epidermidis, according to the skin of the 37 participants in this study), and differences (a highly variable diversity of species living on our epidermis). Our facial skincare routine seems to have a significant impact on this tiny world: the relative abundance of skin microbiota species is higher in participants who only use moisturizer compared to those who use a combination of moisturizer and sunscreen. Certain bacterial species also seem to depend on skincare routines: if you double up on skin hydration with sunscreen, you are likely to promote bacteria such as Corynebacterium sanguinis and Brachybacterium nesterenkovii.

Some figures on skin diseases

  • 4.69 billion cases of skin and subcutaneous tissue disorders, responsible for 41.9 million disability-adjusted life years, were recorded worldwide in 20212.
     
  • Skin and subcutaneous diseases are forming one of the top 10 causes of disability2.
     
  • Most of the skin diseases burden in any community is caused by about 10 common general skin diagnoses and that, with the essential medicines, the right training and support, local health teams could effectively care for these patients2.
     
  • On February 10, 2025, skin diseases were declared a global public health priority by the World Health Organization (WHO)3.

Effect of sun exposure

Another factor that greatly influences this microscopic world on your skin is sun exposure, which is enough to alter the abundance of beneficial microorganisms, such as Malassezia restricta yeast or S. epidermidis bacteria. Do you enjoy sunbathing and regularly use moisturizer? Your lifestyle probably promotes the growth of protective species such as S. epidermidis, which keep pathogens such as S. aureus at bay. And when we talk about the sun, we inevitably think of hyperpigmentation: according to this study, the use of sunscreen appears to be unrelated to the bacteria associated with hyperpigmentation (Corynebacterium spp.). These results still need to be confirmed in larger cohorts.

One thing is certain: when you apply your moisturizer or sunscreen tomorrow, you will spare a thought for the tiny bacteria, fungi, and other viruses that discreetly coexist on the surface of your skin for your own good!

Feel good in your skin... and your skin microbiota

Find out more!
Summary
Off
Sidebar
On
Migrated content
Désactivé
Updated content
Désactivé
Hide image
Off
News Off

Bacterial metabolites and immunotherapy effectiveness

It is not so much the intestinal bacterial species as their metabolic pathways that determine the effectiveness of immunotherapy in cancer treatment. Could this pave the way for therapies combining immunotherapy and biotics?

The gut microbiota

(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.
 
)
significantly improves cancer survival, but its effectiveness varies greatly from one patient to another. Studies have shown a link between certain gut bacteria and efficacy, but the species implicated are inconsistent from one study to another. What if it wasn't so much the species themselves as the metabolites they produce that made all the difference? This is the hypothesis, confirmed by a Dutch team1.

400 000 Each year, approximately 400 000 children develop cancer².

1/6 Cancer is a leading cause of death worldwide, accounting for nearly 10 million deaths in 2020, or nearly one in six deaths².

Bacterial species vary

Analysis of 781 fecal samples from cancer patients treated with ICB shows that bacterial species composition varies greatly between patients and between studies. Furthermore, bacterial diversity does not appear to be related to treatment response. Finally, the profile of the intestinal flora in terms of bacterial species does not allow for a clear distinction between responders and non-responders.

Top 6 (cases)²

The most common in 2020 (in terms of new cases of cancer) were:

  • breast (2.26 million cases);
  • lung (2.21 million cases);
  • colon and rectum (1.93 million cases);
  • prostate (1.41 million cases);
  • skin (non-melanoma) (1.20 million cases); and
  • stomach (1.09 million cases).

Metabolic dysbiosis is associated with poor prognosis

The results are quite different when we look at the metabolism of the gut microbiota rather than its bacterial composition. These functions are relatively stable between patients and between studies. Non-responders show more pronounced functional dysbiosis than responders. Furthermore, the closer the flora's metabolic profile is to that of a healthy control microbiota, the better the response to ICB.

These results are confirmed in a prospective cohort. Thus, an alteration in the metabolic functions of the gut microbiota appears to go hand in hand with a poor response to immunotherapy.

Top 5 (deaths)²

The most common causes of cancer death in 2020 were:

  • lung (1.80 million deaths);
  • colon and rectum (916 000 deaths);
  • liver (830 000 deaths); 
  • stomach (769 000 deaths); and
  • breast (685 000 deaths).

The pathways involved

Finally, the researchers identified various metabolic pathways involved in the response to treatment, including the methyl erythritol phosphate (MEP) pathway. This pathway, which is specific to bacteria, produces phosphoantigens (e.g., HMBPP) and activates Vδ2 lymphocytes involved in antitumor immunity. It is strongly associated with a better response to ICB in different types of cancer. The researchers provide mechanistic evidence: bacteria capable of producing HMBPP (an intermediate in the MEP pathway) stimulate the antitumor activity of Vδ2 T lymphocytes.

A reverse, inhibitory pathway has also been revealed: microbial production of riboflavin is associated with resistance to ICB, induces suppression of immunity mediated by another type of T lymphocyte (MAIT cells, Mucosal-Associated Invariant T cells) and is associated with lower survival rates.

Thus, the metabolic capacity of the microbiota appears to be a major determinant of response to ICB. Will understanding and modulating these microbial functions pave the way for new therapeutic interventions, combining microbiota and immunotherapy to improve the effectiveness of cancer treatments?

This one gut microbe could change the way cancer therapy performs

Learn more
Summary
Off
Sidebar
On
Migrated content
Désactivé
Updated content
Désactivé
Hide image
Off
News Immunotherapy Off

Chronic abdominal pain in children: could it be IBS?

“Mom, dad, my tummy hurts…”. Just an excuse to skip school, or a real illness? If the abdominal pain is recurrent (more than 4 days a month, for more than two months), it may be irritable bowel syndrome, or IBS.

Let’s dispel a few misconceptions from the outset. No, IBS isn’t just in the child’s head: it’s a real, recognized disorder. No, it’s not caused by a poor diet, although certain dietary imbalances can make it worse. No, it’s not the parents’ fault. No, it’s not a serious illness, and it’s certainly not cancer. 

Now that we’ve covered those points, how can you recognize the symptoms? When should you see a healthcare professional? What solutions are available? The answers are below.

The gut microbiota Irritable bowel syndrome (IBS) Functional gastrointestinal disorders
IBS

Definition, epidemiology, symptoms and diagnosis

What is IBS in children?

IBS is a disorder of intestinal function that cannot be explained by any identifiable abnormality (lesion, disease, etc.) 1,2. In short, everything seems fine in young Louise’s stomach, but she really is in pain.

What distinguishes abdominal pain caused by IBS from other types of stomach pain? First, its recurrence: more than 4 days a month, for more than two months. But that’s not all: the symptoms are linked to bowel movements and/or a change in stool frequency and/or appearance (Rome IV criteria 3). 

Is your teenager Raphaël often constipated, but you’re not sure if it’s IBS or functional constipation? It’s actually quite simple: if he has IBS, the pain will not go away when the constipation episode ends 2.

What impact does IBS have on the child’s life and the family?

Although not life-threatening, IBS has a significant impact on children’s quality of life: missed school days, difficulty concentrating and remembering things, giving up sports, social isolation, low self-esteem, sleep disorders and fatigue, to name but a few.

The entire family unit is disrupted, whether emotionally (severe anxiety), economically (cost of treatment, sleep deprivation of parents and impact of medical appointments on their work) or in terms of daily life (giving up certain activities, time spent on diagnosis and treatment) 2,4,5,6.

IBS in children greatly impacts the parents’ professional lives: loss of parental work productivity accounts for nearly a quarter of the cost of care in the European Union. 2

1 in 20 children are affected

Louise and Raphaël are far from being isolated cases. Globally, it is estimated that one in nine children suffer from a functional abdominal disorder, and that one in 20 children suffer specifically from IBS, the most common subtype of these disorders in children  7.

Young Asians may be more affected than Europeans or Americans, but the difference remains slight and may be explained simply by different interpretations of diagnostic criteria  7.

5.8 % Worldwide prevalence of irritable bowel syndrome. ⁷

Risk factors

The likelihood of developing IBS depends on ² :

  • age: Louise may face a rough patch between ages 8 and 12, but once she turns 12, she can expect things to gradually improve on their own;
  • gender: girls may be more affected (although there is no consensus on this point), perhaps due to hormonal factors;
  • a history of premature birth, asthma or eczema, which appear to be associated with an increased risk.

But above all, in the case of both Louise and Raphaël, IBS is more likely to be the result of a combination of factors, starting with psychological ones (anxiety about school or relationships, difficult experiences, etc.), which can make a child more susceptible to abdominal pain.

Has Louise suffered from gastrointestinal infections such as gastroenteritis, or food allergies? Does Raphaël enjoy foods that are too fatty, too spicy or too sweet? This could trigger or worsen their symptoms 2.

The challenge of diagnosis in children

Because there are no specific biomarkers, diagnosis of IBS in children, as in adults, is based on the assessment of clinical symptoms 2,8.

But here lies the first obstacle: symptoms vary from one child to another, to the extent that IBS has been classified into four subtypes.

Other difficulties might include young Louise struggling to describe her symptoms or teenager Raphaël feeling embarrassed to talk about them, while their parents may over- or under-interpret their child’s words depending on their stress or personal experience, increasing the risk of underdiagnosis.

Finally, there are undeniable cultural differences in the perception of pain and intestinal transit 2,8.

Therefore, while IBS is the most common functional gastrointestinal disorder in children, its complex diagnosis often means a long, difficult and expensive experience for families.

Subtypes of irritable bowel syndrome (IBS) and their diagnostic criteria according to the Rome IV criteria:

IBS-C: constipation-predominant

More than a quarter (25%) of stools are classified as severe constipation (hard, difficult-to-pass lumps) or mild to moderate constipation (lumpy, sausage-shaped stools), and less than a quarter (25%) as mild diarrhea (fluffy pieces with ragged edges, a mushy stool) or severe diarrhea (watery stools with no solid pieces).

IBS-D: diarrhea-predominant

More than a quarter (25%) of stools are classified as mild diarrhea (fluffy pieces with ragged edges, a mushy stool) or severe diarrhea (watery stools with no solid pieces), and less than a quarter (25%) as severe constipation (hard, difficult-to-pass lumps) or mild to moderate constipation (lumpy, sausage-shaped stools).

IBS-M: mixed bowel habits

More than a quarter (25%) of stools are classified as severe constipation (hard, difficult-to-pass lumps) or mild to moderate constipation (lumpy, sausage-shaped stools), and more than a quarter (25%) as mild diarrhea (fluffy pieces with ragged edges, a mushy stool) or severe diarrhea (watery stools with no solid pieces).

IBS-U: unclassified

Patients who meet diagnostic criteria for IBS but whose bowel habits cannot be accurately categorized into one of the three groups above.

IBS subcategories are very important in the management of affected children. 2

Where does this pain come from? What science says today

The origin is still very unclear

The mechanisms behind pediatric functional abdominal disorders in general, and IBS in particular, remain poorly understood in 2025. The prevailing theory suggests that IBS results from a disruption of the gut-brain axis 9.

Two mechanisms have been proposed 2 :

  • The top-down model suggests that the disorder begins in the brain: Louise’s symptoms may be triggered by her anxiety, as her brain sends abnormal signals to her gut causing pain, bowel problems and changes in the gut microbiota;
  • The bottom-up model suggests that everything begins in the gut: Louise’s disorder may have been triggered by a gastrointestinal infection that sent pain alert messages to the brain.

While both mechanisms will likely coexist (bidirectional interaction between the brain and the gut) in Louise once the disorder is established, it remains difficult to know which one initiated it 2.

The microbiota: just one piece of the puzzle

Whether it is the cause (bottom-up model) or the consequence (top-down model) of Louise’s IBS, the gut microbiota is now a major line of research. Several factors explain this interest:

  • Louise’s gut microbiota influences her digestion, immunity and gut-brain communication;
  • it is less diverse and some bacteria are more prevalent: this imbalance is called dysbiosis 2,10,11; 
  • a simple transfer of Louise’s microbiota to microbiota-free mice is enough to trigger symptoms in the rodents (visceral sensitivity, changes in bowel function, etc.) 2.

Nevertheless, IBS remains a multifactorial condition: gut flora is just one piece of a much more complex puzzle.

Pr. Premysl Bercik

“Over the past decade, particular attention has been paid to the gut microbiota, which is believed to play a key role in IBS.”

Prof. Premysl Bercik

Further studies are still needed, particularly in children, to confirm the role of the gut microbiota and, perhaps one day, to establish a profile of the gut bacteria associated with the disorder, or even to identify the “microbial signature” specific to each child in order to tailor treatment accordingly 2. This is because the treatment Louise needs is not the same as that needed by Raphaël.

What this means for parents

The gut microbiota can therefore serve as a possible tool 12 as part of a personalized, multidisciplinary therapeutic approach 2,8.

A high-fiber diet and use of specific probiotics (to support beneficial bacteria) or antibiotics (to kill pathogenic bacteria) are strategies that could help Louise or Raphaël, always under medical supervision 8,9.

How can we help a child with IBS?

From diagnosis to treatment decisions

Effective management of Louise’s IBS requires an accurate diagnosis: detailed medical history (background, medications, social and psychological factors) and a physical examination to rule out organic disorders 2,8.

The IBS subtype (is Louise’s IBS constipation-predominant, diarrhea-predominant, mixed or unclassified?) must be identified as it will guide the therapeutic approach and the personalization of treatment over time 2,8.

Once the diagnosis has been made, Louise and her family must work together with the medical team to make decisions: close communication between the child, family and medical staff improves treatment success.

Education should focus on the nature of the diagnosis, the relevance of the connection between the gut and brain, the effects of lifestyle and other triggers, and an outline of potential treatment approaches and options. 13

Multidisciplinary management

Approaches combining multiple therapies, in addition to any medication strategies, deliver the best results 2, 5, 8, 13 :

  • Psychology: communication and dialogue between child, parent and clinician 13
  • Hypnotherapy (home-based or otherwise) 14, cognitive behavioral therapy (CBT), neurostimulation 13
  • Nutrition: a personalized, child-centered approach incorporating advice from a dietitian, promoting fiber intake and avoiding age-inappropriate restrictive diets 13
  • Probiotics, and more specifically lactobacilli such as Lactobacillus rhamnosus GG 5, 13 or L. reuteri 4, and prebiotics to selectively feed the good bacteria;
  • Healthy lifestyle: physical exercise, sleep consistency.

Management of children with IBS may include either non-pharmacological (diet, psychologic interventions, specific fibers and probiotics) and pharmacological strategies (PEG, rifaximin, antispasmodics, gut-brain neuromodulators), as long as they are individualized to the patient’s symptoms, often entailing a multidisciplinary approach. 8

Avoid:

  • self-medication and/or dosages and durations exceeding local recommendations (e.g., repeated use of laxatives); 
  • vicious cycles: parental anxiety, which increases as the child’s symptoms worsen, can undermine treatment. 2

When to consult a healthcare professional ¹³

  • When pain is recurrent (lasting more than 4 days a month, for more than two months), to establish a diagnosis
  • When the child’s quality of life is affected (school absenteeism, isolation, depression, etc.)
  • Before starting any self-treatment (diet or probiotics)
  • In case of prolonged use of over-the-counter painkillers or laxatives 
  • If a parent has concerns (even without warning signs)

IBS is diagnosed by a doctor or pediatrician. They can assess the situation, reassure your child and recommend appropriate treatment. If your child experiences frequent abdominal pain, talk to a healthcare professional. They can guide you to the most suitable solutions.

Patients stories: living with Irritable Bowel Syndrome (IBS)

Recommended by our community:

Warning signs requiring prompt medical attention

  • Family history of chronic inflammatory bowel disease, celiac disease or peptic ulcer
  • Persistent right-sided abdominal pain
  • Difficulty swallowing or pain when swallowing
  • Persistent vomiting
  • Gastrointestinal bleeding
  • Nighttime diarrhea
  • Arthritis
  • Sores or fissures around the anus
  • Unintentional weight loss
  • Slowed statural growth
  • Delayed puberty
  • Unexplained fever

Please note

The Biocodex Microbiota Institute aims to raise awareness about the human microbiome among the general public and healthcare professionals. It is not intended to provide medical advice. For any questions or concerns, please consult a healthcare professional.

Sources

1. Vermeijden NK, de Silva L, Manathunga S, et al Epidemiology of Pediatric Functional Abdominal Pain Disorders: A Meta-Analysis. Pediatrics. 2025 Feb 1;155(2):e2024067677. doi: 10.1542/peds.2024-067677. 

2. Devanarayana NM, Rajindrajith S. Irritable bowel syndrome in children: Current knowledge, challenges and opportunities. World J Gastroenterol. 2018 Jun 7;24(21):2211-2235. doi: 10.3748/wjg.v24.i21.2211. 

3. Rome Foundation. Appendix A: Rome IV Diagnostic Criteria for FGIDs. Available from: https://theromefoundation.org/rome-iv/rome-iv-criteria/. [Last concult: 2026 Jan 20]

4. Romano C, Ferrau' V, Cavataio F, Iacono G, Spina M, Lionetti E, Comisi F, Famiani A, Comito D. Lactobacillus reuteri in children with functional abdominal pain (FAP). J Paediatr Child Health. 2014 Oct;50(10):E68-71. doi: 10.1111/j.1440-1754.2010.01797.x. 

5. Kianifar H, Jafari SA, Kiani M, et al. Probiotic for irritable bowel syndrome in pediatric patients: a randomized controlled clinical trial. Electron Physician. 2015 Sep 16;7(5):1255-60. doi: 10.14661/1255.

6. Vernon-Roberts A, Alexander I, Day AS. Systematic Review of Pediatric Functional Gastrointestinal Disorders (Rome IV Criteria). J Clin Med. 2021 Oct 29;10(21):5087. doi: 10.3390/jcm10215087.

7. Vermeijden NK, de Silva L, Manathunga S, Spoolder D, Korterink J, Vlieger A, Rajindrajith S, Benninga M. Epidemiology of Pediatric Functional Abdominal Pain Disorders: A Meta-Analysis. Pediatrics. 2025 Feb 1;155(2):e2024067677. doi: 10.1542/peds.2024-067677.

8. Di Nardo G, Barbara G, et al. Italian guidelines for the management of irritable bowel syndrome in children and adolescents : Joint Consensus from the Italian Societies of: Gastroenterology, Hepatology and Pediatric Nutrition (SIGENP), Pediatrics (SIP), Gastroenterology and Endoscopy (SIGE) and Neurogastroenterology and Motility (SINGEM). Ital J Pediatr. 2024 Mar 14;50(1):51. doi: 10.1186/s13052-024-01607-y.

9. Gordon M, Sinopoulou V, Tabbers M et al. Psychosocial Interventions for the Treatment of Functional Abdominal Pain Disorders in Children: A Systematic Review and Meta-analysis. JAMA Pediatr. 2022 Jun 1;176(6):560-568. doi: 10.1001/jamapediatrics.2022.0313. 

10. Saulnier DM, Riehle K, Mistretta TA et al. Gastrointestinal microbiome signatures of pediatric patients with irritable bowel syndrome. Gastroenterology. 2011 Nov;141(5):1782-91. doi: 10.1053/j.gastro.2011.06.072.

11. Hollister EB, Oezguen N, Chumpitazi BP, et al. (2019). Leveraging Human Microbiome Features to Diagnose and Stratify Children with Irritable Bowel Syndrome. J Mol Diagn. 2019 May;21(3):449-461. doi: 10.1016/j.jmoldx.2019.01.006.

12. Baştürk A, Artan R, Yılmaz A. Efficacy of synbiotic, probiotic, and prebiotic treatments for irritable bowel syndrome in children: A randomized controlled trial. Turk J Gastroenterol. 2016 Sep;27(5):439-443. doi: 10.5152/tjg.2016.16301. 

13. Groen J, Gordon M, Chogle A, et al. ESPGHAN/NASPGHAN guidelines for treatment of irritable bowel syndrome and functional abdominal pain-not otherwise specified in children aged 4–18 years. J Pediatr Gastroenterol Nutr. 2025 Aug;81(2):442-471. doi:10.1002/jpn3.70070.

14. Rutten JMTM, Vlieger AM, Frankenhuis C et al. Home-Based Hypnotherapy Self-exercises vs Individual Hypnotherapy With a Therapist for Treatment of Pediatric Irritable Bowel Syndrome, Functional Abdominal Pain, or Functional Abdominal Pain Syndrome: A Randomized Clinical Trial. JAMA Pediatr. 2017 May 1;171(5):470-477. doi: 10.1001/jamapediatrics.2017.0091.

Summary
Off
Sidebar
Off
Migrated content
Désactivé
Updated content
Désactivé
Hide image
Off
News Off

Can sweeteners help us lose weight and maintain a healthy gut microbiota?

Somewhat controversial “light” products are once again under the spotlight. A recent European study suggests that sweeteners, when part of a balanced, low-sugar diet, may help facilitate weight loss without harming health or gut microbiota.

The gut microbiota

Can “light” products that use sweeteners help us lose weight? Opinions and scientific data differ and there is no clear answer to this question: some say they are harmful to health and microbiota, others that they are harmless, and others still that they are beneficial.

With more than a billion people obese and 43% of adults overweight worldwide1, the question has major implications.

Sweeteners: good or bad?

In a new study2, European scientists have attempted to provide some unequivocal answers. They studied the impact of sweetened products on weight loss maintenance, health (cholesterol, blood sugar, blood pressure, etc.), and microbiota.

For the study, they recruited 277 obese or overweight people who had recently lost an average of 10 kg following a 2-month low-calorie diet.
 

Taste without calories

Sweeteners are food ingredients that provide a sweet taste but have few or no calories and help us avoid the harmful effects of sugar (tooth decay, increased blood sugar, etc.)4.

  • “Intense” sweeteners include saccharin (E954), aspartame (E951), sucralose, acesulfame potassium (E950), and stevia extract, which are used in cookies, cakes, and beverages (sodas).
  • Polyols include maltitol (E965), isomalt (E953), lactitol (E966), mannitol (E421), sorbitol (E420), and xylitol (E967), which are often found in sugar-free confectionery, particularly chewing gum.

For 10 months, they were put on a balanced, healthy diet relatively low in sugary products, with less than 10% of energy derived from added sugars, as recommended by the World Health Organization.3 There were no restrictions on food quantity.

The participants were divided into two groups:

  • A “sweeteners” group in which all sweet foods and drinks contained sweeteners
  • A “sugar” group, in which these products contained real sugar.

The results?

No problematic effects

Firstly, all participants maintained a significant portion of their weight loss during the 10 months of eating without restriction, proving that a balanced diet helps us stay slim. However, the sweeteners group maintained an additional 1.6 kg of weight loss compared to the sugar group.

Secondly, their cardiometabolic health parameters improved temporarily, although the differences subsequently diminished. In any case, no harmful effects of sweeteners were observed.

Unexpected positive impact on microbiota

More interestingly, the microbiota of the sweeteners group was significantly enriched with bacteria that produce beneficial short-chain fatty acids ( (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. ) ). In particular, the researchers noted the activation of certain metabolic pathways linked to better fat utilization and increased satiety. All these effects were potentially conducive to better weight control.

Only a few digestive symptoms (bloating, gas, loose stools, etc.) were observed in the sweeteners group.

For the authors, this study proves that the prolonged use of sweeteners as part of a healthy, low-sugar diet contributes to maintaining weight loss without any adverse effects on health or the gut microbiota.

Exciting!

When sodas harm your microbiota and your health

Find out more!
Summary
Off
Sidebar
On
Migrated content
Désactivé
Updated content
Désactivé
Hide image
Off
News Off

Sweeteners facilitate weight loss and are safe for microbiota

Accused of disrupting microbiota and metabolic health, sweeteners are the subject of new data. A large-scale European study has recently shed light on their real impact on weight and the gut microbiota.

Can low-calorie sweeteners such as aspartame, sucralose, or acesulfame be part of a diet for managing overweight or obesity? This topic is controversial.

Contradictory scientific data

While some studies have raised concerns that have led the WHO to advise against their use for weight loss and health improvement1, several long-term clinical trials suggest that these additives are at worst harmless and at best beneficial in these areas.

The same problem applies to microbiota: some studies suggest they have adverse effects on certain aspects of the gut microbiota linked to glycemic response, while others show the opposite, and still others show that it is mainly sugary drinks that impact microbiota and metabolites associated with diabetes risk.

29% The market share of calorie-free or low-calorie beverages in Europe.³

17.7% The reduction in added sugar content in beverages in Europe since 2015.³

A real-world study settles the matter

To try shed some light on the matter, a team of researchers recruited 341 overweight or obese individuals (average BMI of 31; 70% women, average age 47) living in Denmark, Greece, Spain, and the Netherlands. Their goal was to test the real effect of replacing sugar with sweeteners after weight loss.

The volunteers first followed a low-calorie diet for two months, then those who lost more than 5% of their body weight (277 people) adopted a healthy, balanced diet without quantity restrictions for the following 10 months.

Half of them consumed sweetened products instead of sugar-rich products (the “sweeteners” group); the other half received conventional sweetened products amounting to less than 10% of their total energy intake, in accordance with WHO recommendations (the “sugar” group).

The researchers analyzed changes in body weight and cardiometabolic markers in all participants, as well as the microbiota composition of a sample of 137 individuals from both groups.

Better weight maintenance and enriched microbiota

Published in Nature Metabolism2, the results show that participants lost an average of 10 kg on the low-calorie diet and that, in both groups, this loss was generally maintained during the 10 months of ad libitum dieting.

Interestingly, the sweeteners group achieved better results, maintaining an additional weight loss of 1.6 kg on average compared to the sugar group, demonstrating the benefits of sweeteners for those seeking to maintain weight loss.

The microbiota of the sweeteners group was also richer in bacteria that produce short-chain fatty acids ( (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. ) ) and methane, which is associated with increased energy expenditure, greater satiety, and improved metabolic health. This is evidence that, contrary to what is commonly stated, sweeteners do not damage microbiota and may even lead to potentially beneficial changes.

There was a temporary improvement in certain cardiometabolic health markers, particularly cholesterol, although this improvement receded after 12 months. There was no deterioration in these markers.

Conclusion

This high-quality study (multicenter, long-term, real-world conditions, etc.) provides evidence that the prolonged use of sweeteners as part of a healthy, low-sugar diet can contribute to weight loss without adverse effects on cardiometabolic parameters or the gut microbiota.

Now you know!

The psychobiotic diet: modulating gut microbiota to reduce stress

Find out more!
Summary
Off
Sidebar
On
Migrated content
Désactivé
Updated content
Désactivé
Hide image
Off
News Off

Why women with blood type A have a lower risk of preterm birth

Women with blood type A may be better protected against certain infections. Why? Because their vagina contains higher levels of a beneficial bacterium called Lactobacillus crispatus.

The vaginal microbiota

More than one in ten children worldwide are born (sidenote: Preterm birth birth before 37 completed weeks of gestation. There are sub-categories of preterm birth, based on gestational age:
- extremely preterm (less than 28 weeks);
- very preterm (between 28 and 32 weeks);
- moderate to late preterm (between 32 and 37 weeks). Source: WHO
)
. A British team recently analyzed data from thousands of young mothers 1 to show that blood type influences the composition of the maternal vaginal microbiota, and with it, immunity and pregnancy outcomes: women with blood type A may be better protected against certain infectious risks thanks to the increased presence in the vagina of beneficial bacterium, Lactobacillus crispatus.

How is this possible?

You’re probably aware that the four main blood types are A, B, AB, and O. These letters indicate the presence of large sugar molecules called antigens, of type A and/or B (or their absence in the case of type O), on the surface of red blood cells. Among other things, these groups determine compatibility for transfusions.

What is less well known is that these “marker” antigens are not only found in the blood: they are also present in other cells (e.g., in the vagina or cervix) and in bodily fluids (including those produced by the cervix and vagina). By contributing to the adhesion or feeding of bacteria, these antigens influence susceptibility to infections. For example, people with type O blood are statistically more vulnerable to Helicobacter pylori, while those with type B blood are more vulnerable to bacteria such as E. coli.

Does each blood type have its own vaginal flora?

Researchers have now confirmed that A, B, and O antigens play a role in vaginal microbiota composition. Women with blood type A are more likely to have a vaginal microbiota dominated by L. crispatus, a beneficial bacterium that very easily attaches to the A marker. A direct consequence of this connection is a less inflammatory vaginal flora and a higher chance of full-term delivery. 

Conversely, L. crispatus is often depleted in women with blood type O, particularly high-risk women due to a previous preterm delivery, and those with blood type B, who generally harbor more of the pathogen S. agalactiae, a bacterium that easily attaches to the B marker.

Some figures on premature birth

  • An estimated 13.4 million babies were born preterm in 2020 (before 37 completed weeks of gestation) ².
     
  • Across countries, the rate of preterm birth ranges from 4–16% of babies born in 2020 ².
     
  • More than 90% of extremely preterm babies (less than 28 weeks) born in low-income countries die within the first few days of life, yet less than 10% of extremely preterm babies die in high-income settings ².
     
  • Preterm birth complications are the leading cause of death among children under 5 years of age, responsible for approximately 900 000 deaths in 2019 ².
     
  • Three-quarters of these deaths could be prevented with current, cost-effective interventions ².

Not so fast

However, do not over-interpret these results, or take liberties with your vaginal flora if you’re in group A. The effect of blood type on the risk of preterm birth remains low and is much less important than factors such as ethnicity (African and Asian women are at higher risk) or medical history. This discovery should primarily be seen as a gateway to future antigen-based therapies aimed at preventing preterm births.

L. iners facing trial for causing preterm birth Vaginal microbiota, a key indicator of the risk of preterm birth?

Read the article
Summary
Off
Sidebar
On
Migrated content
Désactivé
Updated content
Désactivé
Hide image
Off
News Off

Esophageal squamous cell carcinoma (ESCC): could the gut mycobiota lend a hand?

Gut mycobiota profile could serve as a biomarker to predict responses to neoadjuvant immunochemotherapy in the treatment of esophageal squamous cell carcinoma. It could even inspire new therapeutic avenues.

Neoadjuvant immunochemotherapy is seen as a major advance in the treatment of (sidenote: Esophageal Squamous Cell Carcinoma (ESCC) Type of esophageal carcinoma (EC) that can affect any part of the esophagus, but is usually located in the upper or middle third. The average age of onset of ESCC is between the ages of 60 to 70 years and it is more frequently seen in males. It is usually asymptomatic until an advanced disease stage with common presenting symptoms being dysphagia (at first with solids then progressing to fluids) and weight loss. Less commonly odynophagia, hoarseness of voice, coughing, or chest pain can be presenting features. Source : https://www.orpha.net/en/disease/detail/99977 ) . However, it remains difficult to predict which patients will respond favorably to it. Faced with this major challenge, the gut mycobiota appears to offer hope, a Chinese study having found that gut fungal signatures may serve as biomarkers.

Partially repaired dysbiosis

An analysis of fecal samples showed that 68 ESCC patients had a significant dysbiosis of the gut mycobiota prior to treatment compared to 19 healthy controls: reduced diversity, higher abundance of pathogenic fungi and lower presence of beneficial fungi, and less complex ecological networks, indicating fewer synergies. Treatment with neoadjuvant immunochemotherapy improves the diversity and richness of the fungal community and rebalances certain beneficial metabolic pathways, although without reaching the levels seen in healthy subjects.

1/29,400 Esophageal squamous cell carcinoma (ESCC) has an estimated annual incidence of 1/29,400 ¹.

0,1% Although fungi make up less than 0.1% of the microbiome, they possess unique metabolic features that contribute to host functions ².

A mycobiota that predicts success

Most importantly, the profiles of the mycobiota sampled prior to treatment make it possible to distinguish future responders from non-responders. Responders have higher fungal diversity before treatment, more stable networks, suggesting greater resilience, and higher abundance of beneficial fungi (including Candida boidinii) correlated with “hot” tumor signatures (stimulation of T-helper 1 cells, pro-inflammatory cytokines, elevated cytotoxic markers).

What about non-responders? Their mycobiota was enriched in immunosuppressive species associated with characteristics of “cold” tumors (Th-2 cells, immunosuppressive cytokines).
Thus, the mycobiota of responders appears to promote immunity that contributes to tumor phenotypes favorable to the success of immunotherapy, while that of non-responders may contribute to tumor microenvironments that are resistant to immunotherapy.

What is the survival rate for patients with ESCC?

As ESCC is usually diagnosed at an advanced disease stage, the overall prognosis is poor, with an overall 5-year survival of between 10-20%. In patients treated with curative intent the cure rate currently approaches 40% 1.

Predict... and modulate response to treatment

Lastly, the mycobiota appears to be able to accurately and robustly predict future treatment efficacy, with the (sidenote: Area under the curve (AUC) Indication of the discriminatory power of a classification model, for example, an AUC of 1.0 indicates a perfect classifier. It is the probability that the classification model will correctly classify a positive sample. ) reaching 82.9% (genus-level) and even 87.4% (species-level). The Saccharomyces genus appears to be the most robust predictor of non-response. These results suggest that the gut mycobiota may ultimately serve as a biomarker for stratifying patients in ESCC treatment.

Another potential application? Optimizing the results of immunotherapy, with the fungi identified, whether beneficial or harmful, representing targets for modulating the microbiota. The researchers’ initial findings show that administration of Candida boidinii enhanced the efficacy of anti-PD-1 therapy in mice. Could beneficial fungi one day improve treatment responses in patients with ESCC?

Oral microbiota involved in pancreatic cancer

Read the article
Summary
Off
Sidebar
On
Migrated content
Désactivé
Updated content
Désactivé
Hide image
Off
News Oncology Off

Alcoholism: Can gut bacteria reduce its effects on the brain?

Alcoholism appears to disrupt the blood-brain barrier via the gut-brain axis. The gut bacterium Faecalibacterium prausnitzii may mitigate these effects and alcohol-induced cognitive impairment.

Actu GP : Agir sur le microbiote pour réduire la dépendance à l’alcool ?

Ethanol, which can cross the blood-brain barrier (BBB), can damage the central nervous system. But it could also alter this barrier that protects our brain. A pathological process in which the gut-brain axis is involved, according to research published at the end of 2025 1.

The flora of alcoholics

Researchers analyzed the gut microbiota of 30 men who had suffered from alcohol use disorder (AUD) for years, and 30 control subjects. Compared to the control subjects, men with AUD showed cognitive impairment and signs of anxiety, depression, and sleep disorders. Their gut microbiota showed no significant differences in terms of abundance and diversity. However, the composition of their flora was specific: alcohol use disorder was associated with a decrease in Faecalibacterium and an increase in Streptococcus, a bacterium associated with inflammation.

Microbial metabolites present in plasma are also disrupted in cases of AUD: 604 metabolites were overexpressed (particularly in pathways related to lipid metabolism, amino acid metabolism, and bile acid secretion) and 606 were underexpressed. These variations were linked to the abundance of certain bacteria, such as Faecalibacterium.

Alcohol or fecal transplantation, same consequences in mice

The authors also show that chronic alcohol consumption leads to cognitive decline and BBB impairment in mice, with the appearance of leaks in the prefrontal cortex and hippocampus and a decrease in the expression of tight junction proteins in endothelial cells.

But above all, a simple fecal transplant from patients with AUD to axenic mice is enough to cause the same effects.The alteration of the gut microbiota caused by alcohol would therefore be partly responsible for the disruption of the BBB.

  • Harmful alcohol consumption is defined, particularly in Anglo-Saxon countries, as more than 3 drinks per day or 7 per week for women, and more than 4 drinks per day or 14 per week for men 2.
     
  • It is estimated that 400 million people, or 7% of the global population aged 15 and older, had alcohol use disorders in 2019. Of these, 209 million people (3.7% of the global adult population) were dependent on alcohol 3.

The restorative effect of Faecalibacterium prausnitzi

Since Faecalibacterium is less abundant in AUD patients, researchers tested whether F. prausnitzii could protect mice from brain disorders caused by chronic alcohol consumption. And indeed it does: cognitive function is improved, BBB leakage is reduced, and junction proteins are boosted.

Physiologically, F. prausnitzii led to a significant increase in certain short-chain fatty acids (butyric acid, valeric acid, and caproic acid) known for their anti-inflammatory effects. It therefore appears that this bacterium can protect the BBB from ethanol damage through the action of beneficial bacterial metabolites.

Binge drinking: alcohol-related gut dysbiosis may contribute to addiction

Find out more!
Summary
Off
Sidebar
On
Migrated content
Désactivé
Updated content
Désactivé
Hide image
Off
News Gut-brain axis Off

Alcoholism: when the gut microbiota and the brain drink too much

Alcoholism could turn your brain into a sieve. But a tiny bacterium called Faecalibacterium prausnitzii could be the savior and protect your memory.

The gut microbiota

We know that alcohol can damage the brain. But did you know that it could also weaken the barrier that protects the brain from “intruders” coming from the blood? This protection, called the blood-brain barrier, is a bit like a safety net for our gray matter. And surprise: our gut seems to be playing a role in this scenario.

A microbiota not so innocent

Chronic alcoholics not only have problems with memory and concentration, but also with anxiety, depression and sleep disorders. Their gut microbiota is also suffering: Faecalibacterium, an anti-inflammatory bacterium, is less present, while Streptococcus, an inflammatory bacterium, is taking advantage of the situation to set up shop. And that’s not all: the blood plasma of alcoholic men is very different from that of men who are not addicted to drinking, with more than 600 molecules in excess and just as many in deficit. In short, an alcohol use disorder disrupts the gut microbiota, the composition of the blood and the functioning of the brain.

When the brain leaks... literally

To better understand the underlying mechanisms, mice were given alcohol for several weeks. The result: chronic alcohol consumption makes the barrier protecting their noggin permeable; leaks appear in key areas, and proteins essential to the integrity of the blood-brain barrier are down.

More surprisingly, transferring the intestinal microbiota of alcoholic patients to germ-free mice that do not drink alcohol is enough to induce the same type of brain leaks. Thus, the alteration of the intestinal microbiota caused by alcoholism is responsible for the disruption of the blood-brain barrier.

  • Excessive alcohol consumption is defined, particularly in Anglo-Saxon countries, as more than 3 drinks per day or 7 per week for women, and more than 4 drinks per day or 14 per week for men 1.
     
  • In 2019, an estimated 400 million people, or 7% of the world population aged 15 years and older, had alcohol use disorders. Of these, 209 million people (or 3.7% of the world adult population) were dependent on alcohol 2.

Faecalibacterium prausnitzii, the savior?

Since the friendly bacterium Faecalibacterium is missing in alcoholics, the researchers tested whether it could protect mice. Bingo! A few doses of Faecalibacterium prausnitzii allow mice to regain better cognitive abilities and their brain leaks less. How can a gut bacterium protect the barrier that surrounds the brain? Probably through the small anti-inflammatory fatty acids it produces in our digestive system, which slip into the bloodstream and thus reach the brain. Could F. prausnitzii protect against the damage caused by alcoholism? Maybe, although many other studies are still needed, this study 3 having been conducted only in men (not women) and mice. In any case, alcohol remains a substance to be consumed in moderation.

Binge drinking leaves gut microbiota of young people with a hangover

Find out more!
Summary
Off
Sidebar
On
Migrated content
Désactivé
Updated content
Désactivé
Hide image
Off
News Off