If the gut microbiota remains the best known, it’s not the only one...  The vaginal microbiota also plays an essential role in our health. But what do women know today about the role of the vaginal microbiota? What do they know about how to take care of their microbiota? What role do healthcare professionals play in informing patients? To answer these questions, the Biocodex Microbiota Institute commissioned Ipsos to conduct a major international survey on the subject: the International Microbiota Observatory. To carry out this survey, Ipsos questioned 6,500 people in 7 countries (France, Portugal, Spain, USA, Brazil, Mexico and China). For each country, the sample questioned was representative of the country's population aged 18 and over, in terms of gender, age, profession, region and urban area.

The survey was conducted over the Internet from March 21^st to April 7^th, 2023. This exclusive survey reveals a general lack of understanding of the vaginal microbiota’s contribution to health, and underlines the essential role of healthcare professionals in teaching patients, in particular senior patients, about the role of the vaginal microbiota and the behaviors they should adopt to preserve it as well as possible.

Vaginal microbiota: a little-known organ 

• The level of knowledge of vaginal microbiota is fairly low: only 1 in 5 women say they know exactly the meaning of the term “vaginal microbiota” (21%, vs 18% among overall results). 53% of women say they have never heard about it (vs 55% overall). 
• Questioning about the term “vaginal flora”, notions remain superficial: only 1 in 2 women know what the vaginal flora is exactly (49%), a proportion slightly higher than overall results (40%). 
• Regarding the role and importance of microbiota in health, a large majority of women is aware that the vaginal microbiota acts as a barrier, protecting women from pathogenic microorganisms (67%) and that every woman has a vaginal microbiota that is different from any other woman’s (60%). 
• However, only 1 in 2 women know that the vagina is self-cleaning (52%) and that from childhood to menopause, a woman’s vaginal microbiota is not remaining the same (52%). 
• When it comes to specific knowledge regarding delivery, bacterial diversity or unbalanced microbiota, the level of knowledge plummets: only 1 in 3 women know that the vaginal microbiota bacteria are safe for the vagina of women (37%) and that bacterial vaginosis is associated with an imbalance in the vaginal microbiota (35%). 1 in 3 women are also aware that delivery (vaginally or cesarean section) has an impact on the newborn’s gut microbiota (30%). Only 27% say they know that the vaginal microbiota is balanced when its bacterial diversity is low.

Inappropriate behaviors to protect their vaginal microbiota 

• Faced with questions designed to assess their knowledge of the right behaviors to adopt in order to protect the health of their vaginal microbiota, the interviewees gave a relatively low average score of 2,8/5.
• In detail, and except the cotton underwear, where the correct behavior was adopted by 85% of women, a moderate proportion of women have adopted specific behaviors to protect the health of their vaginal microbiota.
• Almost 1 in 2 women say they take vaginal douches (45%) whereas it's bad for their vaginal microbiota. 
• Only 41% say they have taken probiotics and/or prebiotics (either orally or vaginally). 

Information provided by healthcare professionals is still too rare but is needed! 

• Fewer than 1 in 2 women say that their doctor has ever explained to them how to maintain a balanced vaginal microbiota (42%, but only 20% have had this explained to them more than once) or educated on the importance of preserving as much as possible the balance of their vaginal microbiota (40%, but only 18% say they have done so several times). 

• Finally, only 1 in 3 said their doctor had ever taught them what the vaginal microbiota was and what it was used for (35%, and only 14% had had this explained to them several times). 

• Microbiota information is still too rarely provided by physicians, but women need it! 86% of women surveyed said they would like to have more information about the importance of the vaginal microbiota and its impact on health.

Real differences depending on the profile of the people surveyed: women aged 60 and over are the least aware in terms of knowledge 

• Even though they are at an age when health problems linked to aging will, for many of them, become increasingly present, women aged 60 and over are the least aware in terms of knowledge. Only 40% of them know what vaginal microbiota is (vs 47% among all women). 
• Women aged 60 and over are the least likely to know about the vaginal microbiota, with an average score of knowledge of 3,3/8 (vs 3,6/8 overall).  For instance, less than 1 of 4 women aged 60 and over (23%) know that the vaginal microbiota is balanced when its bacterial diversity is low (vs 27% overall). 
• Regarding the adoption of appropriate behaviors to keep their vaginal microbiota balanced, women aged 60 and are (along with the less than 25 yo age group) the ones that have adopted the least correct behaviors. Less than 1 in 2 women aged 60 and over is using a soap-free cleansing solution (49%, vs 52% overall). 
• At the same time, the 60+ age group is the least likely to discuss the subject with their doctor. Only 1 in 4 women aged 60 and over said their doctor had ever taught them what vaginal microbiota was and what it was used for (29% vs. 35% overall).
• Whereas 90% of the 35-44 years old group said they would like to have more information from their healthcare professionals about the importance of the vaginal microbiota and its impact on health, only 79% of the 60+ age group would like to have more information (vs 86% overall).
• On the other hand, the 25-34 and 35-44 age groups have the highest levels of knowledge about what people need to know and do to preserve their vaginal microbiota.
• For example, the 35-44 age group is much more familiar than others with the term "vaginal flora" (47% know exactly what it is vs. 40% overall). 
• The 25-34 age group is the best informed by their physicians. Almost 1 in 2 women were explained by their doctor what the vaginal microbiota is and what its purpose is (48% vs. 35% overall). A large majority of the 25-34 age group women (56% vs. 42% overall) said they received from their physician information about the good behaviors to adopt in order to maintain a good balanced vaginal microbiota. 

The International Microbiota Observatory has also revealed striking contrasts between countries in terms of knowledge, behaviors, and information provided by healthcare professionals. 

About the Biocodex Microbiota Institute

The Biocodex Microbiota Institute is an international hub of knowledge that aims to foster better health by spreading information about human microbiota. To do so, the Institute addresses both healthcare professionals and the general public to raise awareness about the central role of this little-known organ.

BMI-23.42

If the gut microbiota remains the best known, it’s not the only one...  The vaginal microbiota also plays an essential role in our health. But what do women know today about the role of the vaginal microbiota? What do they know about how to take care of their microbiota? What role do healthcare professionals play in informing patients? To answer these questions, the Biocodex Microbiota Institute commissioned Ipsos to conduct a major international survey on the subject: the International Microbiota Observatory. To carry out this survey, Ipsos questioned 6,500 people in 7 countries (France, Portugal, Spain, USA, Brazil, Mexico and China). For each country, the sample questioned was representative of the country's population aged 18 and over, in terms of gender, age, profession, region and urban area.

The survey was conducted over the Internet from March 21^st to April 7^th, 2023. This exclusive survey reveals a general lack of understanding of the vaginal microbiota’s contribution to health, and underlines the essential role of healthcare professionals in teaching patients, in particular senior patients, about the role of the vaginal microbiota and the behaviors they should adopt to preserve it as well as possible.

Vaginal microbiota: a little-known organ 

• The level of knowledge of vaginal microbiota is fairly low: only 1 in 5 women say they know exactly the meaning of the term “vaginal microbiota” (21%, vs 18% among overall results). 53% of women say they have never heard about it (vs 55% overall). 
• Questioning about the term “vaginal flora”, notions remain superficial: only 1 in 2 women know what the vaginal flora is exactly (49%), a proportion slightly higher than overall results (40%). 
• Regarding the role and importance of microbiota in health, a large majority of women is aware that the vaginal microbiota acts as a barrier, protecting women from pathogenic microorganisms (67%) and that every woman has a vaginal microbiota that is different from any other woman’s (60%). 
• However, only 1 in 2 women know that the vagina is self-cleaning (52%) and that from childhood to menopause, a woman’s vaginal microbiota is not remaining the same (52%). 
• When it comes to specific knowledge regarding delivery, bacterial diversity or unbalanced microbiota, the level of knowledge plummets: only 1 in 3 women know that the vaginal microbiota bacteria are safe for the vagina of women (37%) and that bacterial vaginosis is associated with an imbalance in the vaginal microbiota (35%). 1 in 3 women are also aware that delivery (vaginally or cesarean section) has an impact on the newborn’s gut microbiota (30%). Only 27% say they know that the vaginal microbiota is balanced when its bacterial diversity is low.

Inappropriate behaviors to protect their vaginal microbiota 

• Faced with questions designed to assess their knowledge of the right behaviors to adopt in order to protect the health of their vaginal microbiota, the interviewees gave a relatively low average score of 2,8/5.
• In detail, and except the cotton underwear, where the correct behavior was adopted by 85% of women, a moderate proportion of women have adopted specific behaviors to protect the health of their vaginal microbiota.
• Almost 1 in 2 women say they take vaginal douches (45%) whereas it's bad for their vaginal microbiota. 
• Only 41% say they have taken probiotics and/or prebiotics (either orally or vaginally). 

Information provided by healthcare professionals is still too rare but is needed! 

• Fewer than 1 in 2 women say that their doctor has ever explained to them how to maintain a balanced vaginal microbiota (42%, but only 20% have had this explained to them more than once) or educated on the importance of preserving as much as possible the balance of their vaginal microbiota (40%, but only 18% say they have done so several times). 

• Finally, only 1 in 3 said their doctor had ever taught them what the vaginal microbiota was and what it was used for (35%, and only 14% had had this explained to them several times). 

• Microbiota information is still too rarely provided by physicians, but women need it! 86% of women surveyed said they would like to have more information about the importance of the vaginal microbiota and its impact on health.

Real differences depending on the profile of the people surveyed: women aged 60 and over are the least aware in terms of knowledge 

• Even though they are at an age when health problems linked to aging will, for many of them, become increasingly present, women aged 60 and over are the least aware in terms of knowledge. Only 40% of them know what vaginal microbiota is (vs 47% among all women). 
• Women aged 60 and over are the least likely to know about the vaginal microbiota, with an average score of knowledge of 3,3/8 (vs 3,6/8 overall).  For instance, less than 1 of 4 women aged 60 and over (23%) know that the vaginal microbiota is balanced when its bacterial diversity is low (vs 27% overall). 
• Regarding the adoption of appropriate behaviors to keep their vaginal microbiota balanced, women aged 60 and are (along with the less than 25 yo age group) the ones that have adopted the least correct behaviors. Less than 1 in 2 women aged 60 and over is using a soap-free cleansing solution (49%, vs 52% overall). 
• At the same time, the 60+ age group is the least likely to discuss the subject with their doctor. Only 1 in 4 women aged 60 and over said their doctor had ever taught them what vaginal microbiota was and what it was used for (29% vs. 35% overall).
• Whereas 90% of the 35-44 years old group said they would like to have more information from their healthcare professionals about the importance of the vaginal microbiota and its impact on health, only 79% of the 60+ age group would like to have more information (vs 86% overall).
• On the other hand, the 25-34 and 35-44 age groups have the highest levels of knowledge about what people need to know and do to preserve their vaginal microbiota.
• For example, the 35-44 age group is much more familiar than others with the term "vaginal flora" (47% know exactly what it is vs. 40% overall). 
• The 25-34 age group is the best informed by their physicians. Almost 1 in 2 women were explained by their doctor what the vaginal microbiota is and what its purpose is (48% vs. 35% overall). A large majority of the 25-34 age group women (56% vs. 42% overall) said they received from their physician information about the good behaviors to adopt in order to maintain a good balanced vaginal microbiota. 

The International Microbiota Observatory has also revealed striking contrasts between countries in terms of knowledge, behaviors, and information provided by healthcare professionals.

About the Biocodex Microbiota Institute

The Biocodex Microbiota Institute is an international hub of knowledge that aims to foster better health by spreading information about human microbiota. To do so, the Institute addresses both healthcare professionals and the general public to raise awareness about the central role of this little-known organ.

BMI-23.42

It's a faithful relationship. For the third year, Biocodex Microbiota Institute is celebrating World Microbiome Day running with two objectives: raise awareness among lay public about the importance of microbiota and valorize microbiota research through the Biocodex Microbiota Foundation national grant winners.

A look back at the latest microbiota research rewarded by Biocodex Microbiota Foundation

They are scientists, professors, physicians specialized in different specialties (gastroenterology, pediatrics, neurology, cardiology, microbiology, pharmacokinetics…). They come from Portugal, Finland, Belgium, Mexico, United States… They have made major advances in the role of the microbiota on health and associated diseases… And they all have won the Biocodex Microbiota Foundation national’s grant!

Since 2017, The Biocodex Microbiota Foundation rewards national research initiatives which aim to understand the interaction between microbiota and different diseases. On World Microbiome Day 2022, in order to give visibility to researchers, the Biocodex Microbiota Institute gives the floor to the national grant winners through dedicated interviews.

What did the Biocodex Microbiota Foundation national research grant allow them to do? What impact have their research results on patient care? Available on the HCPs’ dedicated section, these testimonies give us a clear idea of the variety and diversity of research projects currently underway. These interviews will be activated via the Institute Twitter’s account during 10 days and Biocodex Microbiota Foundation’s LinkedIn by June 27st. Don’t hesitate to share and spread the good new!

About the Biocodex Microbiota Institute

The Biocodex Microbiota Institute is an international hub of knowledge dedicated to microbiota. The Institute educates the lay public and healthcare professionals on the importance of microbiota on healthcare and well-being.

About the Biocodex Microbiota Foundation

Since 2017, the Biocodex Microbiota Foundation has been working to improve science's understanding of the human microbiota. Each year, the Foundation contributes to the funding of global research on microbiota via grants awarded to innovative scientific research projects. Calls for projects are regularly launched on a specific theme related to the microbiota, with the most promising projects then selected by an international scientific committee made up of independent experts.

BMI-22.38

According to the WHO, diarrhea is currently defined as the passage of at least three loose or liquid stools per day. Recognizing that the joint presence of 2 criteria (frequency + consistency) is necessary, the frequent passing of formed stools (that is, of normal consistency) does not constitute diarrhea, nor does the passing of loose stools at a normal frequency, such as with breastfeeding babies.

However, while common in mild forms, diarrhea can be life-threatening. It was responsible for 1.6 million deaths in 2016, mainly among malnourished or immunocompromised children, or people living with HIV. ¹ The main cause of these deaths was severe dehydration associated with fluid loss due to the repeated passing of stools.

Most cases of acute diarrhea are due to infections from pathogenic bacterial, viral or parasitic microorganisms.^1-3

What is bacterial diarrhea? 

Diarrhea is defined as the passage of at least three loose or liquid stools per day, and infectious diarrhea is diarrhea caused by infection by a pathogen (virus, bacteria, or parasite) ^1-3. If the pathogen is a bacterium, the diarrhea is said to be “bacterial”. 

Which bacteria are responsible?

The bacteria involved are often⁶:

• Shigella, responsible for an illness called shigellosis and for 212,438 deaths worldwide in 2016,
• and Vibrio cholerae, responsible for dreaded cholera epidemics and for 107,290 recorded deaths in 2016, generally in poor populations without access to clean drinking water.

However, these are not the only ones. The bacteria Salmonella or Escherichia coli sometimes make the headlines in Western countries when they contaminate foodstuffs (raw ground meat, cheese, etc.) and necessitate much-publicized product recalls from supermarkets.

How do bacteria cause acute diarrhea?

In bacterial diarrhea, as in infectious diarrhea in general, it all begins with a confrontation between a pathogen (in this case a bacterium), transmitted by contaminated food, polluted water or contact with a sick person, and the host (our body). However, the dangerous nature of bacteria varies from one bacterium to another, and behind one name, there are actually many types of bacteria. For example, there are over 2,500 different salmonella strains of varying degrees of aggressiveness⁷. The same applies to Escherichia coli: not all E. coli are pathogenic, and among those that are pathogenic, there are many different strains^2,8.>

The outcome of the confrontation between the bacterium and the body depends on complex equilibriums, which largely involve the gut microbiota. Thus, animals lacking in intestinal flora are very susceptible to bacteria responsible for diarrhea: a micro-dose of certain strains of salmonella is enough to cause a fatal infection, while a dose 100 to 100 million times stronger is necessary to kill mice with intact gut microbiota⁹. The science behind this difference Without microbiota, the immune system is immature and thus unarmed against an invasion of pathogens, which are also able to freely settle in with no other bacteria occupying the territory⁹.

When the bacteria get the upper hand, they secrete specific toxins, which explains why each bacterial diarrhea is different^2,10:

• the toxin from Shigella destroys the cells of the digestive tract lining and thus causes severe diarrhea containing blood and mucus; <
• the toxin from Vibrio cholerae disrupts the absorption and secretion of ions and water in the digestive tract, causing a very liquid diarrhea rich in ions;
• the different types of E. coli produce different toxins: Enteropathogenic E. coli causes persistent liquid diarrhea (usually among infants), while Enteroinvasive E. coli causes diarrhea containing bile and mucus, etc.

Acute bacterial diarrhea caused by an infectious agent creates a major intestinal dysbiosis². It will take the microbiota several weeks to recover its equilibrium, which, in some cases, never returns to its initial state^2,11.

How to prevent bacterial diarrhea?

Due to the dangerous nature of Shigella, there is hope of a vaccine which could eventually not only prevent the 200,000 or so deaths caused annually by this bacteria, but could also reduce the need for antibiotics and the emergence of resistance that makes treatment ineffective. Several vaccines against Shigella are currently undergoing development, but none are yet officially approved¹².

Another research avenue: the gut microbiota. In humans, a “healthy” gut microbiota is considered a means of preventing cholera¹³<. In addition, probiotics are seen as a means of limiting the severity of some bacterial infections²: the probiotic yeast Saccharomyces boulardii could facilitate the restoration of gut microbiota in children suffering from acute diarrhea¹⁴; the probiotic E. coli (non-pathogenic) inhibits the formation of biofilms by pathogenic bacteria, including pathogenic E. coli²; a trio of specific strains of Lactobacillus, Bifidobacterium and Streptococcus reduces the duration of bloody diarrhea (dysentery) and hospitalization².

To these preventive measures, of course, are added the advice of hygiene and social distancing, which apply to all types of infectious diarrhea (see boxed text). In the specific case of food-borne infections (salmonella, E. Coli), care should be taken to cook food properly (E. coli is killed by heat, which explains why contaminated foods are often raw or undercooked meats).

How to treat bacterial diarrhea?

Quite common and usually not serious, bacterial diarrhea often clears up on its own. Attention should be paid, however, to the risk of dehydration among the very young, the elderly and immunocompromised patients. Loss of water and electrolytes (sodium, potassium and chloride ions) should be compensated for:

• orally (with oral rehydration solutions, or ORS);
• or intravenously in the most serious cases.

Health professionals may also recommend certain probiotic strains to treat acute infectious diarrhea in children. These good bacteria reduce the duration of diarrhea, and/or the duration of hospitalization, and/or the quantity of stools (ESPGHAN 2023).

Key points to remember about bacterial infectious diarrhea

• Diarrhea is defined as the passage of at least three loose or liquid stools per day, and infectious diarrhea is diarrhea caused by infection by a pathogen (virus, bacteria, or parasite). Due to the resulting dehydration, diarrhea was responsible for 1.6 million deaths in 2016, mainly among malnourished or immunocompromised children or people living with HIV^1-3.
• In cases of infection by a bacterium, diarrhea is said to be “bacterial”. The bacteria Shigella (shigellosis) and Vibrio cholerae (cholera) are the deadliest in poor countries without access to clean drinking water. In Western countries, Salmonella and Escherichia coli are associated with food contamination, while C. difficile is the main bacterium responsible for nosocomial infectious diarrhea in adults⁶.
• Sometimes, the gut microbiota manage to counter the infection; at other times, the bacteria kills the gut microbiota and causes diarrhea of which the characteristics (presence of blood, presence of mucus, passing of a large amount of liquid, etc.) depend on the type of bacteria involved ^2,1.
•  Prevention of viral diarrhea rests above all on good hygiene practices (washing and cooking of food, hand-washing, social distancing, etc.). Probiotics could have a place in the prevention of certain bacterial infections ². Lastly, researchers are working on the development of vaccines against Shigella ¹².
• treatment of bacterial diarrhea focuses on fighting dehydration.Antibiotics can be prescribed by health care professionals for people at risk (infants, the elderly, immunocompromised patients) or when the infection spreads from the intestines to other parts of the body ⁷. Probiotics can also be prescribed to reduce diarrhea and hospitalization time(ESPGHAN 2023).

What is parasitic diarrhea?

Diarrhea is defined as the passage of at least three loose or liquid stools per day, and infectious diarrhea is diarrhea caused by infection by a pathogen (virus, bacteria, or parasite). ^1-3 If the pathogen is a parasite, the diarrhea is said to be “parasitic”.

Which parasites are responsible?

Intestinal parasites can be classified into two main categories : ^6-8

• protozoa, organisms made up of a single cell and measuring less than one millimeter, among which the best-known are Giardia intestinalis (responsible for giardiasis), Entamoeba histolytica (which causes the dreaded amebiasis), Cyclospora cayetanensis (cyclosporiasis) and Cryptosporidium spp (cryptosporidiosis);
• helminths, organisms made up of multiple cells, better known under the name worms, of which the most well-known is undeniably Ascaris lumbricoides.

Infections by these 2 types of parasites are common: 350 million people are estimated to be infected by the 3 most common types of protozoa, and 895 million by helminths transmitted through soil. Due to the globalization of food production, international travel and waves of migration, protozoa infections are now more common in the West than worm infections. ⁶

How do parasites cause acute parasitic diarrhea?

In parasitic diarrhea, as in infectious diarrhea in general, it all begins with a confrontation between a pathogen (in this case a parasite), usually transmitted by contaminated food or polluted water, and the host (our body). However, parasitic infection does not necessarily lead to symptoms such as diarrhea. Infections by the protozoan Entamoeba histolytica are usually asymptomatic, but can provoke an invasive disease of the large intestine in immunocompromised patients.⁷ The same applies in the case of worms: a mild infection often goes unnoticed, while the presence of a large number of worms can cause a whole series of symptoms such as growth disorders and problems with physical development. This is because the worms feed on the tissues of the host, leading to intestinal blood loss and hindering absorption of nutrients. ^8,9 

Each parasite has its own habits : ⁷

• among protozoa, Giardia intestinalis infects the upper part of the small intestine and can cause, 6 to 15 days after infection, acute diarrhea that is very liquid, while Entamoeba histolytica attacks the large intestine and can cause bloody diarrhea with mucus ;
• the worm Ascaris lumbricoides infects us through the ingestion of its eggs, which may be present on improperly washed food (fruits and vegetables) or in polluted water. Its eggs release larvae into the digestive tract. These in turn pass through the wall of the digestive tract and reach the lungs via the bloodstream, where they may cause their first symptoms (early pulmonary phase). This is just the start. The larvae climb the trachea up to the esophagus and slide down the esophagus and then the digestive tract, where they turn into adults (late intestinal phase, with diarrhea, mild abdominal pain, weight loss, nausea and vomiting), which lay eggs that are eliminated in stools.

How to prevent parasitic diarrhea?

Prevention rests above all on hygiene advice which applies to all types of infectious diarrhea.

Another avenue inspired by an observation: different people react differently to parasites; some are asymptomatic while others suffer from acute diarrhea. The gut microbiota can explain this clinical variation: for example, in Bangladesh, low abundance of the bacterium Megasphaera before and at the time of detection of the parasite Cryptosporidium has been associated with parasitic diarrhea in infants, which suggests that the gut microbiota may play a role in the severity of cryptosporidiosis. ¹⁰

If we look at helminths, the connections between these worms and gut microbiota are also the subject of multiple studies. Complex interactions exist between the two, but also with the host's immune system. However, intestinal worms should not necessarily be avoided: in small doses, they could have beneficial health effects, such as resistance to other digestive system pathogens or even the prevention of allergic ailments.¹¹

How to treat parasitic diarrhea?

As with all types of diarrhea, parasitic diarrhea exposes the very young, the elderly and immunocompromised patients in particular to the risk of dehydration. Treatment thus focuses primarily on treating the symptoms, namely, fighting the loss of water and electrolytes (sodium, potassium and chloride ions):

• orally (with oral rehydration solutions, or ORS);
• or intravenously in the most serious cases.

When a health care professional suspects that a parasitic infection could be the cause of diarrhea (e.g. if a patient has recently returned from the tropics), they will usually request examination of a stool sample in order to identify the possible parasite. However, it is not always so simple. The parasite may not be present in all stools (which would require multiple samples), and the presence of a small quantity of a parasite does not necessarily mean that the culprit has been found. This makes parasitic infections such as giardiasis potentially difficult to diagnose, and the treatment decision also depends on the history and symptoms of the patient. ¹²

Key points to remember about parasitic infectious diarrhea

• Diarrhea is defined as the passage of at least three loose or liquid stools per day, and infectious diarrhea is diarrhea caused by infection by a pathogen (virus, bacteria, or parasite). Due to the resulting dehydration, diarrhea was responsible for 1.6 million deaths in 2016, mainly among malnourished or immunocompromised children or people living with HIV. ^1-3
• In cases of infection by a parasite, diarrhea is said to be “parasitic”. There are 2 types of intestinal parasites: protozoa, measuring less than one millimeter, among which the best-known are Giardia intestinalis, responsible for giardiasis, and Entamoeba histolytica, which causes the dreaded amebiasis; and helminths, better known by the name worms, of which the most well-known is undeniably ascaris (roundworm). ^6-8
• In the great majority of cases, the presence of digestive parasites is asymptomatic and not severe, possibly even beneficial (immunity). Sometimes, however, they cause diarrhea, of which the characteristics (presence of blood, presence of mucus, significant amount of liquid, etc.) depend on the parasite. ⁷
• Prevention of parasitic diarrhea rests above all on good hygiene practices (washing and cooking of food, hand-washing) and on the development of access to clean drinking water. Microbiota are also the subject of multiple studies, since they may explain the variation in symptoms and severity from one person to another. ¹⁰
• The treatment of parasitic diarrhea focuses on fighting dehydration. If the parasite is identified, the prescription of medication can be considered. ⁹ Systematic deworming programs are also proposed. ⁸

What is viral diarrhea?

Diarrhea is defined as the passage of at least three loose or liquid stools per day, and infectious diarrhea is diarrhea caused by infection by a pathogen (virus, bacteria, or parasite). ^1-3  If the pathogen is a virus, the diarrhea is said to be “viral”.

Which viruses are responsible?

While rotavirus is the deadliest (210,000 estimated deaths in 2016 among children under the age of 5), it is far from the only virus responsible for acute diarrhea or even death: adenovirus, norovirus, sapovirus and astrovirus each kill between 17,000 and 37,000 young children every year. ⁶

Note: SARS-Cov-2, the code name of the virus responsible for the COVID-19 pandemic, can also cause diarrhea. However, the frequency of these cases is difficult to quantify. Figures vary widely from one study to another, with some researchers reporting an incidence rate of diarrhea in 2% of cases, others in 50%! ⁷

How does a small virus cause acute viral diarrhea?

In viral diarrhea, as in infectious diarrhea in general, it all begins with a confrontation between a pathogen (in this case a virus) and the host. The outcome of this confrontation depends on complex equilibriums, which largely involve the gut microbiota: in mice, for example, certain bacteria seem to be able to prevent or even cure a rotavirus infection. ⁸ The same virus will thus have a different effect depending on the state of the gut microbiota of the infected person. A less diversified microbiota would be more susceptible to the virus. ¹²

When the virus gains the upper hand, the process is always essentially the same: the virus infects the cells that line the small intestine and causes lesions that hinder the absorption of fluids. ⁹ The result is very liquid diarrhea (but without the presence of blood) which may be accompanied by other symptoms such as vomiting, nausea, abdominal cramps and fever. ¹⁰ This is the famous viral gastroenteritis, which reappears every winter. Particularly severe in the case of infection by rotavirus, which causes more pronounced symptoms, it is usually accompanied by dysbiosis of the gut microbiota, unsettled by the invasion of this virus. ^11,12

How to prevent viral diarrhea?

Given the danger of rotavirus for frail individuals, preventive vaccines have been developed to reduce its mortality rate in young children. It is estimated that the vaccination of infants against rotavirus prevented 139,000 deaths in children under the age of five in the period 2006 to 2019. This figure is considered to be both significant yet low considering the hopes pinned on the vaccination: the vaccine seems to be less effective in low- or moderate-income countries (which are paradoxically the most affected).

Among the factors that might explain this lower effectiveness is the composition of the body’s microbiota, which affects the immune response to the vaccination in the gut. ^13-16 To this preventive measure, of course, are added the advice of hygiene and social distancing, which apply to all types of infectious diarrhea.

How to treat viral diarrhea?

Very common and usually not serious, viral diarrhea can nonetheless lead to severe dehydration in the most frail individuals (infants, malnourished children, immunocompromised adults, the elderly). Treatment focuses on fighting the loss of water and electrolytes (e.g. replenishing lost sodium, potassium and chloride ions):

• orally (with oral rehydration solutions, or ORS);
• or intravenously in the most serious cases.

Health professionals may also recommend certain probiotic strains to treat acute gastroenteritis in children. These good bacteria reduce the duration of diarrhea, and/or the duration of hospitalization, and/or the quantity of stools (ESPGHAN 2023).

Key points to remember

• Diarrhea is defined as the passage of at least three loose or liquid stools per day, and infectious diarrhea is diarrhea caused by infection by a pathogen (virus, bacteria, or parasite). Due to the resulting dehydration, diarrhea was responsible for 1.6 million deaths in 2016, mainly among malnourished or immunocompromised children or people living with HIV. ^1-3
• In cases of infection by a virus, diarrhea is said to be “viral”. The rotavirus virus causes the most deaths, followed, far behind, by adenovirus, norovirus, sapovirus and astrovirus. ⁶
• Sometimes, the gut microbiota manage to counter the infection; at other times, the virus kills the gut microbiota and causes watery diarrhea, which may be combined with other symptoms  such as vomiting, nausea, abdominal cramps and fever. This is viral gastroenteritis. ¹⁰
• Prevention of viral diarrhea rests on the vaccination of infants against rotavirus (less effective in low- or moderate-income countries), access to clean drinking water, and hygiene and social distancing practices which apply to all types of infectious diarrhea. ^13-16
• The treatment of viral diarrhea focuses on fighting dehydration. Certain probiotic strains can be prescribed for the treatment of acute gastroenteritis in children (ESPGHAN 2023). Antibiotics, on the other hand, are ineffective against viruses and can also worsen the diarrhea.

Physical activity and gastrointestinal distress

Physical activity is, in its nature, putting stress on the body, particularly if it is intense or prolonged. While moderate amounts of exercise have a positive effect on gut permeability and inflammation ¹, sustained and intense exercise can have deleterious effects on the gut functionality ², in agreement with gastrointestinal distress and disorders being common, especially among endurance athletes. ³

Since the gut microbiome is linked to the gastrointestinal physiology ⁴, the gut microbiome could potentially play a role in gastrointestinal distress and physiological responses to exercise, influencing athletic performance. 

Effects of the gut microbiota on endurance exercise

Pointing towards a more direct effect of the gut microbiota on endurance exercise, a landmark study published in Nature Medicine in 2019 ¹⁰, found that marathon runners have elevated levels of Veillonella. The researchers found that lactate, formed during prolonged endurance, was transported from the circulation into the intestine where it was metabolized by Veillonella into propionate.

When the scientists fed mice the lactate-utilizing Veillonella microbes or administered propionate via intracolonic infusion, the endurance of the mice improved, as reflected by increased treadmill run performance. ¹⁰ Intriguingly, the study proposed that gut microbes may directly enhance athletic performance. Another recent study also reported that the gut microbiome is involved in stimulating gut-derived signals to the brain affecting motivation for exercise in mice. ¹¹

These discoveries suggest that by targeting the gut microbiome, athletes could potentially improve their athletic performance.

Gut-centric dietary strategies to influence athletic performance

An obvious way to target the gut microbiome is through the diet, since microbes feed on dietary components reaching the colon. Traditionally, many sports-centric dietary strategies focused on high protein, high carbohydrates, low fiber intake, and food avoidance. While such strategies may be sufficient to support host metabolism, restore glycogen stores, and reduce gastrointestinal distress during exercise ¹², the lack of dietary fiber could over time be detrimental to the athlete’s gut microbiota and bowel habits. ¹³

In contrast, gut-directed dietary strategies including adequate dietary fiber from a variety of foods, probiotics, and prebiotics, could support a diverse gut microbiome ¹³ and contribute to regular bowel habits. ⁴ The intake of dietary fiber and prebiotics fuels the resident gut microbes as they serve as substrates for the microbes. Once these indigestible components reach the colon, the microbes ferment them into gas and short-chain fatty acids.

While too much gas can cause discomfort and bloating, the resulting three main short-chain fatty acids – acetate, propionate and butyrate are associated with colonic health and integrity. These molecules can act locally in the gut, affecting our intestinal barrier function, motility, nervous system, and immune system, as well as in distant organs, affecting host metabolism. ¹⁴

To nurture our invisible microbial coach in the gut, scientists and athletes need to develop gut-centric dietary strategies that, on the one hand, reduce gastrointestinal symptoms during exercise and, on the other hand, support a diverse gut microbiome, stimulate colonic fermentation, and promote regular bowel movements — aspects that may all be key for athletic performance.

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Bacteria, viruses, fungi (including yeasts) and even parasites: a whole flora, known as the “gut microbiota”, inhabits our digestive system.

And it's all for our own good: the intestinal microbiota aids digestion, contributes to the maturation of our immune system, protects us from pathogens and intestinal toxins, and so on. This list of benefits is far from exhaustive, as the gut microbiota has many other strings to its bow, including when it comes to sport: this invisible coach could help us in our efforts, improve our times and motivate us for training sessions!

The prospects opened up by the discovery of these links between microbiota, the digestive system and sport are immense: can we optimize athlete performance through a personalized approach to microbiota?

Dive into the heart of a microscopic world to discover this bidirectional relationship with our muscular and mental performance.

Dive into microbiota and sport exhibition

Find out more about the link between microbiota and sport 

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Expert opinion

Dr. Henrik Roager is an Associate Professor and researcher at the University of Copenhagen. He leads the Microbiome & Metabolomics research group, focusing on how gut microbiota contributes to digestion, health, and athletic performance. Watch the video to know what Dr. Henrik Roager has to say about the contribution of microbiomes in sports.

To find out more

Discover our selection of articles on the health and microbiota benefits of sport.

Do athletes have a specific microbiota?

A number of studies have looked closely at the microbiota of top-level athletes in an attempt to identify any specific characteristics, or even the bacteria associated with their performance. Generally speaking, athletes (sidenote: Athlete A competitive sportsman or sportswoman who strives for a high level of performance through training.
Source: Rousseau AS. Nutrition, santé et performance du sportif d’endurance / Nutrition, health and performance of endurance athletes. Cahiers de Nutrition et Diététique. 2022 eb ;57(1) : 78-94 ) ' flora does indeed seem different.

First of all, the gut microbiota of athletes is more diverse. The athletes’ cardiorespiratory fitness, and more specifically their maximum oxygen consumption (VO2max (sidenote: VO2max A criterion specific to each athlete, VO2max is the maximum quantity of oxygen that the body can extract from the air and transport to the muscle fibers to meet their needs during exercise. The higher the VO2max, the better the performance. When this criterion is low, sporting ability is limited, and specific training will be needed to boost it. ) ), seems to be linked to the diversity of their gut microbiota. ²

Secondly, the microbiota of athletes is richer in beneficial bacteria (Bifidobacterium, Lactobacilli, and Akkermansia) and produces more valuable short-chain fatty acids (SCFAs (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. ) ) ^3,4. However, there are major differences based on the sport and the athlete. For example, in the microbiota of the aforementioned rugby players, several bacterial taxa are over-represented, starting with Akkermansiaceae. ¹ In marathon runners and cross-country skiers, the gut flora is richer in bacteria from the large Firmicutes family (which includes “good bacteria” lactobacilli) and less rich in Bacteroidetes. The result is a favorable ratio between these two bacterial families (F/B ratio) associated with a higher VO2max, a key factor in performance. ⁵

Prevotella, bacteria associated with better physical performance, are also over-represented in marathon runners. ⁵ The same was true of professional cyclists in the US: Prevotella abundance increased with the number of hours they trained per week. ²

However, the big question that remains is whether athletes’ specific microbiota is the cause of their extraordinary performance or the consequence of their intense sporting activities, combined with a very specific diet. The answer is probably a virtuous circle involving a bit of both.

Is modulating the gut microbiota an ideal strategy for improving athletes’ health and performance?

A direct consequence of the relationship between the gut microbiota and sporting performance is the temptation for athletes to optimize their gut flora, whether through diet (to nourish their bacteria) or probiotics. ⁶

On the dietary side, research is beginning to take up the subject, focusing in particular on the benefits of a high-fiber diet for athletes’ microbiota and digestive health. ³ After all, athletes tend to opt for pasta over lentils and salad. However, their fiber intake should be proportional to their high caloric intake: 14 g of fiber per 1,000 kcal per day should help promote gastrointestinal health and performance. Furthermore, fiber intake should be avoided just before or after exercise, to avoid adding the effects of fiber (bloating, accelerated transit) to an already strained digestive system. ³

As for probiotics, the wide range of strains, doses, sports, and athletes makes it difficult to reach any conclusions. ³ Nevertheless, scientific studies have reported beneficial effects on general health, particularly immunity. In female swimmers, a probiotic yoghurt containing Lactobacillus acidophilus spp., Lactobacillus delbrueckii bulgaricus, Bifidobacterium bifidum, and Streptococcus salivarus thermophilus limits episodes of respiratory infection after competition. In rugby players, a probiotic containing several strains also reduces the frequency of upper respiratory tract disorders and gastrointestinal symptoms. Other studies show an improvement in immune function. ⁶

In terms of performance, certain experiments on mice seem promising. The most striking example is the bacterium Veillonella atypica, associated with the performance of marathon runners, which transforms a waste product of their muscles (lactate) into fuel (propionate).

By simply adding this bacterium to the digestive tract of mice, they become the new stars of the treadmill. ⁷ On the other hand, mice fed a diet devoid of fibers that are fermentable by bacteria drag themselves along the treadmill, losing muscle masse. ⁴ However, these results in rodents are preliminary and must be confirmed by studies on humans.