What is the lung microbiota?

In contrast to its big brother, gut microbiota, it is only very recently that lung microbiota has been investigated. This delay can be partly explained by the difficulty of collecting samples and accessing the lungs themselves, both of which often require the use of an invasive method.³ In addition, the risk of bacterial infection of the upper airways is a real issue.⁴ Lung flora was first identified in 2010;⁵ there have since been very few studies devoted to elucidating the role of the communities of micro-organisms that live there.³  

Nonetheless, our understanding of the composition of the lung microbiota can be summed up in three points:

• Low density of bacteria⁵
• High level of biodiversity. In healthy individuals, bacteria from the Prevotella, Veillonella, Streptococcus, Neisseria, Fusobacterium and Haemophilus⁵ genera are predominant in the lungs. Maintaining the balance of this bacteria relies on the rhythm of inhalation and exhalation⁶
• A tremendous abundance of “anaerobic” bacteria, which develop in the absence of oxygen. These are species of bacteria belonging to the Fusobacterium, Porphyromonas, Prevotella and Veillonella⁷ genera

Nor are bacteria the only micro-organisms (sidenote: Microorganisms Living organisms that are too small to be seen with the naked eye. They include bacteria, viruses, fungi, archaea and protozoa, and are commonly referred to as “microbes”. What is microbiology? Microbiology Society. ) that develop in the lung microbiota of healthy individuals! Fungi (species belonging to the Eremothecium, Systenostrema and Malassezia genera and to the Davidiellaceae family) and viruses (member species of the Anelloviridae family, along with a large number of bacteriophages (sidenote: Bacteriophage Virus that specifically targets and infects bacteria Scitable by Nature education_2014. Bacteriophage definition ) ) are also found to live there.² Recent discoveries have also identified the presence of archaea (sidenote: Archaea Type of micro-organism (different from bacteria) found in all environments, including extreme environments Archaea. Microbiology Society )  in the lungs.⁸ Lastly, while these micro-organisms form an integral part of the lung microbiota, the data currently available are limited. 

Why does the lung microbiota play a major role in our health?

The lung microbiota plays a key role in maintaining the balance of lung function. It acts in four major ways:

• As a barrier to pathogens and an aid to resistance against respiratory infections,⁹ in exactly the same way as the gut microbiota
• It plays a defensive role by actively helping to stimulate innate and adaptive immunity (sidenote: Innate and adaptive immunity  The human body protects itself using two kinds of defense mechanisms: innate immunity and adaptive immunity. Innate immunity is the first line of defense against disease agents and is an immediate response, while adaptive immunity is delayed but provides lasting protection Janeway CA Jr, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease. 5th edition. New York: Garland Science; 2001. Principles of innate and adaptive immunity. ) in case of infections^10,11
• It is involved in the maturation of the pulmonary immune system, enabling, inter alia, tolerance to allergens¹²
• It affects the morphology of the lungs and more specifically, the number of pulmonary alveoli, according to studies in mice¹³

Diseases linked to an imbalance in lung microbiota

When there is an imbalance in the composition of the lung microbiota, a dysbiosis (sidenote: Dysbiosis Generally defined as an alteration in the composition and function of the microbiota caused by a combination of environmental and individual-specific factors. Levy M, Kolodziejczyk AA, Thaiss CA, et al. Dysbiosis and the immune system. Nat Rev Immunol. 2017;17(4):219-232.   ) ¹⁴ emerges, which may be linked to various diseases. Scientific studies to date have not always been able to determine whether the dysbiosis causes or results from such diseases, though.

Let’s take a closer look at the disorders linked to pulmonary dysbiosis:

• winter respiratory infections such as colds and flu (most often viral), where there is an imbalance in lung immunity, along with dysbiosis¹⁵ in the lungs and gut
• asthma:¹⁶ a chronic disease of the respiratory system affecting more than 260 million people worldwide.¹⁷ This condition is associated with an imbalance in the lung microbiota,¹⁶ as well as in gut¹⁸ and nasal¹⁹ microbiota
• cystic fibrosis, a rare genetic disease that mainly affects the airways and the digestive system²⁰
• chronic obstructive pulmonary disease (COPD), which is characterised by progressive narrowing and permanent obstruction of the airways and lungs, causing difficulty breathing¹⁶

Looking after your lung microbiota

You now know about the important role played by the lung microbiota and the gut-lung axis in your health. Researchers have grasped this fully and are currently investigating strategies to prevent or cure lung infections.^23,24

When it comes to preventing winter respiratory infections, there have been some encouraging results when combining probiotics with prebiotics.²⁵ In infants, certain probiotics may well prevent winter infections as early as the first few months of life.²⁶ Lastly, some studies in students have demonstrated the value of using probiotic treatment to achieve a significant reduction in symptom duration.^27,28
 

BMI-21.41

What is exactly the human urinary microbiota?

You have probably heard less about the urinary microbiota than its more well-known neighbors, the gut microbiota and the vaginal microbiota. This is no surprise, since it is a less rich and diverse environment³ whose role requires further research.¹

However, recent studies have shown that the urinary tract is home to a unique urinary microbiota.^4,5 Urine analyses based on culture-dependent methods have traditionally identified pathogens (sidenote: Pathogens A pathogen is a microorganism that causes, or may cause, disease. Pirofski LA, Casadevall A. Q and A: What is a pathogen? A question that begs the point. BMC Biol. 2012 Jan 31;10:6. ) responsible for urinary tract infections (UTIs), such as Escherichia coli.

Advances in detection technologies have led to the discovery of additional bacteria in the urinary microbiota. The genus Lactobacillus is frequently identified, while Gardnerella, Streptococcus, and Corynebacterium also tend to be present, although to a lesser degree.³ In addition, communities of fungi have also been observed.⁶ 

Why is the urinary microbiota a key player in our health?

Microorganisms (sidenote: Microorganisms Living organisms that are too small to be seen with the naked eye. They include bacteria, viruses, fungi, archaea and protozoa, and are commonly referred to as “microbes”. What is microbiology? Microbiology Society. ) inhabiting the urinary microbiota can play a protective role in our health.¹ However, under certain conditions, they can also influence urinary tract infections.²

Several mechanisms have been described: for example, the bacterial genera Lactobacillus and Streptococcus secrete lactic acid, which is believed to play a protective role against pathogens.⁸ Lactic acid lowers the pH of urine (≈ 4.5), creating a microenvironment that is hostile to most pathogenic bacteria.

Furthermore, Lactobacillus (sidenote: Lactobacilli Rod-shaped bacteria whose main characteristic is the production of lactic acid, from where they get the name “lactic acid bacteria”.  Lactobacilli are present in the oral, vaginal and gut microbiota of humans, but also in plants and animals. They are found in fermented foods, such as dairy products (e.g. certain cheeses and yoghurts), pickles, sauerkraut, etc. Lactobacilli are also found in probiotics, with certain species recognized for their beneficial properties.   W. H. Holzapfel et B. J. Wood, The Genera of Lactic Acid Bacteria, 2, Springer-Verlag, 1st ed. 1995 (2012), 411 p. « The genus Lactobacillus par W. P. Hammes, R. F. Vogel Tannock GW. A special fondness for lactobacilli. Appl Environ Microbiol. 2004 Jun;70(6):3189-94. Smith TJ, Rigassio-Radler D, Denmark R, et al. Effect of Lactobacillus rhamnosus LGG® and Bifidobacterium animalis ssp. lactis BB-12® on health-related quality of life in college students affected by upper respiratory infections. Br J Nutr. 2013 Jun;109(11):1999-2007. ) produces additional substances, antibacterial metabolites such as hydrogen peroxide, which also protect against pathogens.⁹ As with the gut microbiota, the urinary microbiota acts as a barrier against pathogens.¹

What diseases are associated with an unbalanced urinary microbiota?

As with all microbiota (gut microbiota, lung microbiota, etc.), when the composition of the urinary microbiota is disrupted, an imbalance, or “dysbiosis (sidenote: Dysbiosis Generally defined as an alteration in the composition and function of the microbiota caused by a combination of environmental and individual-specific factors. Levy M, Kolodziejczyk AA, Thaiss CA, et al. Dysbiosis and the immune system. Nat Rev Immunol. 2017;17(4):219-232.   ) ”,⁹ results. Studies comparing the urinary microbiota of healthy subjects to that of patients suffering from various urinary diseases have identified a link between these diseases and the composition of the urinary microbiota.

In fact, studies published to date have demonstrated a clear role for the urinary microbiota in urinary tract infections (UTIs).^8,10 For example, decreased diversity in the urinary microbiota may be a risk factor for urinary tract infections.¹¹

Furthermore, disorders such as urgency urinary incontinence,¹² interstitial cystitis,¹³ and sexually transmitted infections¹⁴ have also been associated with an altered urinary microbiota.

How can we take care of our microbiota? We can have a direct influence on it.

• Diet: it is common knowledge that dietary factors can influence the risk of urinary tract infections. Certain food and dietary products (such as cranberry juice or fermented dairy products containing probiotics) may help reduce the risk of recurrent infection by regulating the microbiota.⁸

• Probiotics: oral and vaginal probiotic have been successful in decreasing recurrence rates for UTIs.¹⁵

• Water: drinking plenty of water is important, but researchers have not yet confirmed that it can cure UTIs.¹

BMI-21.12

What is exactly the human gut microbiota?

You probably have already heard about the “gut flora”, well, scientifically, it is called “the intestinal microbiota” or to put it more simply “the gut microbiota”. What is the definition of gut microbiota ? It consists of trillions¹ of microorganisms (sidenote: Microorganisms Living organisms that are too small to be seen with the naked eye. They include bacteria, viruses, fungi, archaea and protozoa, and are commonly referred to as “microbes”. What is microbiology? Microbiology Society. ) that populate your intestines like bacteria, viruses, fungi (including yeasts), and even parasites.

By the way, microbiota and microbiome are two words often used as one to the other but they have two different meanings while microbiota is used to talk about the microorganism and answer the question “who is there?” basically the “individuals”, the microbiome talks about their genome “what is inside of them”² to answer the question “what are they doing” meaning their function.

Each one of us has a unique microbiota, like a fingerprint.¹ When you’re born, fecal and vaginal microorganisms transmitted by your mother during vaginal delivery, or environmental microorganisms for cesarean delivery,³ induce the start of your gut microbiota colonization⁴. It takes around three years for the gut microbiota to build up, diversify and stabilize.⁵ During adulthood,⁶ the composition is relatively stable until old age when it undergoes profound changes again to become slightly impoverished.⁷

Why is gut microbiota important for your health?

The gut microbiota can be considered a functional organ of the human body. Why should we take care of our microbiota ? It works closely with your intestines and have 4 important roles:

What affects your gut microbiota ?

The composition of the gut microbiota is characterized by its high diversity (number of different species present in an individual) and its abundance (total number of microorganisms present). When the composition is disrupted, the balance is broken, and a dysbiosis  (sidenote: Dysbiosis Generally defined as an alteration in the composition and function of the microbiota caused by a combination of environmental and individual-specific factors. Levy M, Kolodziejczyk AA, Thaiss CA, et al. Dysbiosis and the immune system. Nat Rev Immunol. 2017;17(4):219-232.   ) emerges,¹³ which can be associated with several diseases. 

Numerous factors can have an impact on the diversity and composition of the gut microbiota. Among these factors, these are the following:

Factors linked to the individual themselves, such as:

• The age⁶
• Genetics¹³ 
• Certain illnesses and injuries¹³ 

Others factors are linked to the individual's environment:

• Medication use: antibiotics, anti-inflammatories, etc.⁸ 
• Infections (viral gastroenteritis…)¹³
• Lifestyle: unbalanced diet (high-fat diet for example), or changes in diet, stress, smoking, alcoohol excess, etc. ¹³

What are the diseases that could be linked to gut microbiota ?

Dysbiosis, cause or consequence of these diseases? The question has not yet been answered with certainty by scientific studies.

But the role of the human gut microbiota doesn’t stop at the gut: recent studies have identified that the gut microbiota may play a role beyond the gastrointestinal tract. In fact, gut microbiota has been associated with several extra-intestinal diseases: for example, acne²³ , allergies²⁴ , obesity,²⁵ anxiety disorders,²⁶ autism-spectrum disorders²⁶…And that’s not all of it. It seems that gut microbiota can also be associated with neurodegenerative diseases like Alzheimer’s,²⁷ Parkinson’s.²⁸ In fact, there is bidirectional communication between the gut and the brain, named “gut- brain- axis”, and gut microbiota could influence these interactions. That is why your gut is sometimes called your second brain.

How to take care of your microbiota?

You know by now the central role of the gut microbiota in human health. So how should you take care of your own microbiota? How to improve your gut microbiota ? Many scientific studies raised the question of how to avoid any disruption in its composition and keep it as balanced as possible.²⁹ The answer is not as simple as bring in good bacteria or yeast to fill or enrich the existing microbiota or replace the bad ones. In fact, the idea is to influence the microbiota to help it to function smoothly thereby improving host health.³⁰

BMI 21.10

What is exactly the human vaginal microbiota?

The vaginal microbiota or vaginal flora consists of the hundreds of bacteria and the smaller number of fungi (Candida) that populate the vagina.¹

For most women (and in contrast to the gut microbiota) the vaginal microbiota is balanced when its diversity is low (c. 200 bacterial species) and when lactobacilli – rod-shaped bacteria – predominate.¹

The vaginal microbiota is a dynamic community subject to the influence of factors that include ethnic origin, sex hormones, hormonal contraception, sexual behavior, vaginal douching, diet, smoking habits, social environment (e.g. living space) and genes.^1,3

At the same time, the vaginal flora doesn’t live alone. The anus and the entrance to the vagina are located right next to each other and intestinal bacteria from the former can colonize the latter.⁴ The gut therefore constitutes a natural reservoir of lactobacilli for the vagina, which is important for the balance of the vaginal flora^.5,6,7

How does the vaginal microbiota change throughout life?

The body evolves throughout life, and so does the vaginal microbiota. The vaginal microbiota’s composition changes greatly from childhood through adulthood to the menopause.¹ Hormonal changes alter the rhythm of our lives, and impact the vaginal microbiota as well. For example, menstruation temporarily alters vaginal microbial diversity.⁸ The microbiota also plays a role in childbirth.^1,10 During pregnancy, physiological changes occur to adapt the mother’s body to the fetus and vice versa.⁹ In pregnant woman, the vaginal microbiota is more stable, less rich and less diverse⁹, with high levels of estrogen ensuring the outright dominance of lactobacilli.^1,8 Lastly, at menopause the vaginal microbiota settles into a new balance.¹⁰

Why is the vaginal microbiota a key factor in health?

The bacteria in the vaginal microbiota help maintain a healthy vaginal environment.¹ Some of these bacteria, particularly lactobacilli, prevent pathogenic microorganisms (sidenote: Microorganisms Living organisms too small to see with the naked eye. This includes bacteria, viruses, fungi, archaea, protozoa, etc., collectively known as ’microbes’. Source: What is microbiology? Microbiology Society. ) from establishing themselves in the vagina. A number of mechanisms have been proposed:

• by producing lactic acid the microbiota promotes an acidic environment (pH ≤ 4.5) unsuitable for many pathogens^11,12
• defensive compounds produced by the microbiota, such as hydrogen peroxide (H₂O₂) or antibacterial substances (bacteriocins), attack alien bacteria, viruses and fungi^11,12
• the microbiota acts as a barrier, making it difficult for pathogens to establish themselves on the vaginal walls. The presence of lactobacilli accelerates the renewal of the epithelium, to which pathogens may try to attach themselves^11,12
• the microbiota facilitates the production by the vaginal epithelium of a protective mucus which keeps pathogens at bay^11,12
• by stimulating the woman’s immune system, the microbiota improves her ability to fight attacks by pathogens^11,12

An unbalanced vaginal microbiota: what are the associated diseases?

Stress, illness, excessive hygiene (douches), medication (antibiotic therapy, etc.), alcohol, tobacco… all of these factors can impact the composition of the vaginal microbiota.^8,13 When the composition of the microbiota is unbalanced, we have what we call a “dysbiosis (sidenote: Dysbiosis Generally defined as an alteration in the composition and function of the microbiota caused by a combination of environmental and individual-specific factors. Levy M, Kolodziejczyk AA, Thaiss CA, et al. Dysbiosis and the immune system. Nat Rev Immunol. 2017;17(4):219-232.   ) ”.^8,11

A vaginal dysbiosis is when lactobacilli, the key bacteria in the vaginal flora, lose their predominance, paving the way for opportunistic microorganisms to colonize the vagina.^8,11 Their presence is often associated with vaginal discharge, itching and burning, or a fishy smell, but can also be asymptomatic.⁸

A vaginal dysbiosis is associated to:

• a bacterial vaginosis, due to colonization by pathogenic bacteria¹
• a candidiasis, due to the proliferation of a fungus⁸
• reduced fertility¹¹
• a higher risk of premature birth¹

Knowing what has a direct impact on it, how can we take care of our vaginal microbiota?

Taking care of the vaginal microbiota is essential. Daily intimate hygiene is crucial to prevent dysbiosis. There’s much false information out there, so it’s important to understand the DO’S and DON’TS.

Daily:

While vaginal douching is not recommended since it alters the vaginal flora, external washing of the vulva with a suitable intimate gel¹⁵ helps reduce the unwanted accumulation of vaginal discharge, sweat, urine and fecal contaminants.¹⁶

To contribute to the good health of vaginal microbiota:

Hygiene is still necessary¹⁵, but it’s not enough. Several options for the vaginal microbiota already exist or are currently being tested:

• Probiotics: Probiotics are live microorganisms that, when administered in appropriate amounts, confer health benefits on the host.^17,18 They can reduce or safely correct microbiota imbalances. Probiotics for women administered either via the vagina or orally may help rebalance the vaginal flora, improve symptoms and reduce the risk of recurrence of various vaginal infection^13,19,20,21. This is true both for women of childbearing age and postmenopausal women.^13,20,21
• Prebiotics: Prebiotics are specific non-digestible dietary fibers that confer a health benefit. They are selectively used by beneficial microorganisms in the host’s microbiota.^22,23 When added to probiotics in specific products, they are known as symbiotics.²⁴ Prebiotics for women are thought to promote the growth of lactobacilli and to help restore healthy vaginal acidity.^19,25,26

BMI-21.12 TEST

Dysbiosis caused by a course of antibiotics can lead to Clostridioides difficile infection. This pathogen is associated with significant morbidity and mortality, as well as high health care costs worldwide. Identifying markers of this infection could contribute to improving treatment and reducing the severity of infection.

More than 1000 patients recruited from 34 European hospitals.

In this observational, prospective, multicenter study, the gut microbiota of hospitalized patients aged over 50 years was analyzed (16S rRNA sequencing combined with an oligotyping technique for identifying C. difficile) the day before starting antibiotic therapy with the aim of identifying microbial markers predictive of antibiotic-associated diarrhea (AAD) and C. difficile infection (CDI). A longitudinal analysis was also performed to assess the impact of certain antibiotics (sidenote: Penicillin + beta-lactamase inhibitor, other classes of beta-lactams, Fluoroquinolones )  on the gut microbiota.

Markers predictive of CDI

135 patients reported diarrhea in the 90 days following treatment, 15 of which had CDI. Researchers observed that the diversity of the microbiota on D1, prior to any antibiotic therapy, was lower in patients who had suffered CDI compared with those who had suffered AAD or patients who had not had diarrhea at all. The composition of their gut microbiota was also different: Enterococcus was more abundant, whereas there was a reduction in Blautia, Ruminococcus, Porphyromonas, Bifidobacteria, Odoribacter, Prevotella and Ezakiella spp. compared with patients who had not had CDI. Ruminococcus, Ezakiella and Odoribacter spp., five days prior to the onset of CDI in this cohort. These predictive markers were compared with those from a Canadian cohort of elderly patients who suffered CDI. In exactly the same way, the gut diversity was reduced; there was an increase in Enterococcus and a reduction in Ruminococcus, Ezakiella and Odoribacter spp. five days prior to the onset of infection.

Antibiotic-induced dysbiosis

The authors also found that antibiotics induced dysbiosis, which was classed as such six days after the start of treatment. The gut microbiota of patients taking beta-lactam antibiotics (a different class from penicillin) suffered the most disruption. All beta-lactams (regardless of whether they are combined with a beta-lactamase inhibitor or not) increase the abundance of Enterococcus. Treatment with penicillin combined with a beta-lactamase inhibitor was also associated with a reduction in bacteria belonging to the Clostridiales Incertae Sedis XI family, known for being associated with a reduced risk of CDI. The other classes of beta-lactams induced a reduction in bacteria belonging to Lachnospiraceae, including butyrate-producing species, known for their beneficial effects on health. Collectively, all the classes of antibiotics studied considerably altered the composition of the gut microbiota and are well documented, as they involve a high risk of developing CDI.

All women know that the hormonal fluctuations of the menstrual cycle influence, among other things, the vaginal flora and gut transit. So could female contraceptives, particularly those that work on hormones, modify, for better or worse, the dynamics of the vaginal and gut microbiota?

Oral contraceptives boost the vaginal flora...

The vaginal microbiota has a unique quality: it is in good health when its diversity is low and rod-shaped bacteria, lactobacilli, predominate. This contrasts with other microbiota, including the gut microbiota, which are considered in balance when highly diversified. The predominance of lactobacilli protects the vagina against infection, since lactobacilli release lactic acid (among other substances), which slows the proliferation of pathogens. However, where dominant lactobacilli are replaced by other types of bacteria and the vaginal flora loses its balance (dysbiosis), bacterial vaginosis can result. However, hormonal contraceptives (oral or vaginal) seem to reduce the risk of contracting this disease.¹ How? By boosting the lactobacilli! The estrogens contained in these contraceptives result in large quantities of glycogen being deposited on the vaginal walls. Glycogen is the favorite food of lactobacilli and allows the bacteria to multiply and produce more lactic acid. What about other types of contraception? Although research in this area is still limited, the vaginal ring does not seem to cause any substantial modification of the vaginal flora, while IUDs (whether copper or hormonal) appear to have no effect.¹

...but slightly disturb the gut microbiota

Unlike the vaginal microbiota, a healthy gut flora should be diverse. However, the pill artificially maintains constant levels of estrogen and progesterone in the blood, which appears to disturb the gut microbiota. In a recent study involving 16 healthy premenopausal women², oral contraceptives were associated with a minor decrease in gut microbiota diversity and differences in the abundance of several bacterial taxa. However, it is not yet known whether the hormones in the pill have a direct effect on the gut microbiota or whether they work indirectly via other physiological processes that themselves affect the bacteria in the gut. Despite this, these preliminary results show that the pill may affect women’s health. Hence the need for further studies to gain a more complete understanding of the impact of these drugs on the gut microbiota.

Delayed growth, long-term consequences on the metabolism, immunity, and cognitive development… malnutrition in children is still a global health problem, with therapeutic and food-related solutions that are still incomplete or even insufficient. Researchers have realized that the gut microbiota of these children has maturation deficits, with seemingly underdeveloped microbial communities compared to those of healthy children. The aim of this study, which steers away from the norm, is to concentrate on the gut microbiota in order to influence growth, and to see how a food supplement that targets gut microbiota (MDCF-2) improves the growth of 118 malnourished Bangladeshi children versus a pre-existing ready-to-use supplementary food (RUSF).

Children who grow and put on weight more quickly

Although RUSF has more calories, the children who received MDCF-2 gained more weight and grew more quickly. In addition, children who received MDCF-2 presented with higher levels of proteins associated with bone growth and neurological development. Another encouraging result: 21 types of bacteria that are positively linked with changes in growth were detected.

Hope for millions of children?

To date, over 30 million children under the age of five years still suffer from malnutrition world-wide. This study suggests that the healthy growth of children is inexorably linked to optimal development of their gut microbial communities after birth. Larger studies conducted in more varied geographical areas should make it possible to confirm the advantages of a nutritional therapy that targets the gut microbiota compared with traditional strategies. Confirmation of these therapeutic claims would mark a significant success in the fight against the consequences of child malnutrition.

Over 30 million children aged under 5 years suffer from moderate acute malnutrition (MAM) (sidenote: Moderate Acute Malnutrition (MAM) Defined by the World Health Organization as a weight/height ratio two to three standard deviations lower than the median of the age cohort )  world-wide. The main characteristic of this global scourge is that these children have an immature gut microbiota (GM). During a previous clinical trial (sidenote: Raman AS, Gehrig JL, Venkatesh S, et al. A sparse covarying unit that describes healthy and impaired human gut microbiota development. Science. 2019;365(6449):eaau4735. ) , the authors of this study defined a prototype food supplement (MDCF-2), which made it possible to restore the GM of children aged 12 to 18 months suffering from MAM. This new study aims to confirm the efficacy of MDCF-2 in children suffering from MAM in a larger study conducted over a longer period of time.

An interventional study conducted on 123 Bangladeshi children

In this randomized, controlled trial, 123 Bangladeshi children (12 to 18 months old) suffering from MAM received either MDCF-2 supplementation (204 kcal per daily dose of 50 g), or an existing ready-to-use supplementary food (RUSF, 247 kcal per daily dose of 50 g) twice a day for three months, followed by a one-month follow-up. At the same time, the team of researchers monitored weight, height, and arm circumference on a weekly basis, and also took blood and stool samples regularly.

Faster growth, more weight gain

Of the 118 children who completed the study (59 in each group), those in the MDCF-2 group had grown more rapidly than those in the RUSF group. For the children in the MDCF-2 group, the mean weekly variation in the weight-for-height index was 0.021, versus 0.010 in the RUSF group. As for weight-for-age, the mean weekly variation was 0.017 in the MDCF-2 group and 0.010 in the RUSF group. The variations in arm circumference and height-for-age index were similar in both groups.

Blood and intestinal biomarkers identified

After supplementation with MDCF-2, 714 proteins were significantly modified, versus 82 in the RUSF group. Although some of them were associated with musculoskeletal and nervous system development (p<0.001), 70 were also correlated with the weight-for-height index. On the other hand, proinflammatory markers, accentuated by malnutrition at the start of the study, were more largely reduced by MDCF-2 supplementation. With regard to the microbiota, MDCF-2 supplementation made it possible to significantly increase 21 bacterial taxa positively associated with the weight-for-height index (p<0.001) and inversely, to reduce two bacterial taxa (Escherichia coli and a species of Bifidobacterium) negatively associated with the weight-for-height index (p<0.001).

This study backs the following statement: adequate calorie and nutritional supply is insufficient for remedying the consequences of long-term malnutrition. According to the authors, optimal maturation of the GM is a priority. In order to evaluate the efficacy of this new therapeutic approach, larger studies are needed, which should be conducted in different geographical locations and in a broader pediatric age bracket.

We all know how vegetables are good for us when it comes to nutrition, digestion, hydration, and reducing stress, but with this new discovery their benefits seem endless: the winning combination of nitrates and their effects on our oral bacteria. Like many other vegetables, beetroot is rich in inorganic nitrate, which is transformed by the oral bacteria into nitrite and then nitric oxide (NO). NO is beneficial to the health of our arteries and our grey matter. The only problem is that NO production diminishes with age. Could a glass of nitrate-rich beetroot juice help roll back the years?

Ten days of nitrate-rich beetroot juice for an oral microbiota in top form

This supplementation has fast-acting effects: a study has shown that consuming beetroot juice for ten days was enough to considerably modify the oral microbiota of about thirty Icelanders aged 70-80. Consuming the nitrate-rich juice influenced a number of bacterial groups in their oral microbiota. Specifically, there was a decrease in certain bacteria associated with inflammation (Prevotella and Veillonella) and in the dreaded Clostridium difficile, which can infect the gut and cause diarrhea. Conversely, other bacteria became relatively more abundant, such as a group comprising Neisseria and Haemophilus, both of which are associated with periodontal health, younger age, lower BMI, and abstinence from smoking.

Blood pressure down, attention up, morale excellent

Nitrate supplementation via beetroot juice reduced average blood pressure in participants. High blood pressure is a risk factor for cognitive decline. In this study, a reduction in blood pressure went hand in hand with an increase in certain bacteria (Streptococcus and Rothia) whose presence increases following absorption of the juice. Moreover, nitrate-rich beetroot juice also proved beneficial to cognitive health. However, the participants in the study were active and healthy seniors whose blood pressure was generally good. It remains to be seen whether this beneficial effect can be reproduced in other age groups and in people in poorer health. In the meantime, we should all include as many vegetables as possible in our meals and smoothies!

Sources

^{Vanhatalo A, L'Heureux JE, Kelly J et al. Network analysis of nitrate-sensitive oral microbiome reveals interactions with cognitive function and cardiovascular health across dietary interventions. Redox Biol. 2021 Mar 5;41:101933.}

Endometriosis (EMS) is an inflammatory disease characterized by the presence of endometrial tissue outside the uterine cavity. Different studies suggest a prevalence for the disease of between 6% and 15% for women of reproductive age. EMS can cause severe primary dysmenorrhea, reduced infertility, and pelvic mass, seriously affecting women’s quality of life. The pathogenesis of EMS is still poorly understood, but the microbiota may be involved. Certain hypotheses blame inflammatory endotoxins found in the peritoneal cavity, such as bacterial lipopolysaccharide (LPS). These inflammatory endotoxins could regulate the pro-inflammatory reaction and promote the growth of endometriosis.¹

Vaginal lactobacillus diminished

To further investigate the “bacterial contamination hypothesis”, a team collected microbiota samples from along the reproductive tracts of 36 women with endometriosis and 14 controls who had undergone surgery for a benign gynecological tumor. The results? An increasingly pronounced dysbiosis as one moves up the reproductive tract, a decrease in Lactobacillus in the vaginal flora which becomes more pronounced as one moves up towards the endometrium, and specific OTUs (sidenote: Operational Taxonomic Unit groups of organisms usually not cultivated or not identified, classified on the basis of the similarity of the DNA sequencing of a given gene. Frequently used as an equivalent to the concept of species )  in the cervical mucus which increase in the upper genital tract (endometrial samples and peritoneal fluid). This alteration of the microbiota all along the reproductive tract suggests that certain bacteria may be involved in the pathogenesis of EMS.

Role of the gut microbiota?

EMS is far from being limited to gynecological symptoms: up to 90% of patients report gastrointestinal symptoms as well.² Two studies, one in Sweden² (66 EMS patients, 198 matched controls) and the other in Shanghai³ (12 EMS patients with moderate to severe forms of the disease, 12 controls), examined the link between the gut microbiota and EMS: the alpha (sidenote: Beta diversity Rate of variation in species composition, calculated by comparing the number of unique taxa in each ecosystem ) , and to a lesser extent beta (sidenote: Beta diversity Rate of variation in species composition, calculated by comparing the number of unique taxa in each ecosystem ) , diversity of the EMS patients’ flora was found to be lower than that of the controls. In addition, the abundance of bacterial taxa differed. In the Chinese study, Prevotella was dominant among the EMS patients, while Coprococcus prevailed among the controls. Additionally, the gut microbiota of the EMS group was enriched for certain microbial function categories (environmental information processing, endocrine system, and immune system). Serum levels of hormones (particularly estradiol) and inflammatory factors (notably IL-8) were significantly higher in the women with EMS.³ Lastly, correlations were detected between the abundance of both Blautia and Dorea and estradiol level, and between Subdoligranulum abundance and IL-8 level.³ Thus, there are associations between the gut microbiota and both serum hormones and inflammatory factors in EMS.

Estrogen or inflammatory etiology?

EMS is an estrogen-dependent disease² and EMS patients generally have high estrogen levels in the serum.³ The gut microbiota, including Ruminococcaceae and Clostridia, may affect estrogen levels in the serum by modulating the reabsorption of estrogen excreted in the bile which eventually enters the gut.³ Other authors suggest a regulatory role for the gut microbiota in inflammatory processes outside the gastrointestinal tract.² In other words, although correlations have been observed and hypotheses suggested, the actual mechanisms involved have not yet been elucidated. Nevertheless, these three studies highlight the involvement of the microbiota of the reproductive and digestive tracts in EMS, giving hope for an improvement in the diagnosis and management of the disease.