Excessive alcohol use is responsible for three million deaths each year and is a causal factor in more than 200 diseases.¹ On the other hand, when consumed in moderation (sidenote: Moderation Adults of legal drinking age can choose not to drink or to drink in moderation by limiting intake to 2 drinks or less in a day for men and 1 drink or less in a day for women, when alcohol is consumed. Drinking less is better for health than drinking more. https://www.niaaa.nih.gov/alcohol-health/overview-alcohol-consumption/moderate-binge-drinking ) , beer is thought to have beneficial effects on health, particularly in the prevention of cardiovascular disease. These beneficial effects have long been known for both beer and wine, but it is not yet clear whether they are due to moderate consumption or to the compounds contained in these beverages, such as the polyphenols (sidenote: Polyphenol An organic molecule present in plant matter. https://www.medicalnewstoday.com/articles/319728 ) found in large quantities in beer.

Beneficial effect... with or without alcohol?

To shed some light on the matter, a team of Portuguese researchers² carried out a study comparing the effects of alcoholic and non-alcoholic beer on the gut microbiota and on markers of cardiometabolic health (weight, fat mass, cholesterol levels, insulin resistance, etc.).

^Sources

Without changing their diet, 10 men drank 33 cl of lager (alcohol content 5.2%) each day with their dinner for four weeks, while another 9 men consumed a non-alcoholic beer.

A more diverse gut microbiota

Good (and surprising) news for beer lovers: no weight gain and no increase in liver enzymes were noted.  There were also no major changes in cardiometabolic health markers. Stool analyzes revealed greater microbial diversity in the gut microbiota (a sign of good health), but also a tendency towards greater fecal alkaline phosphatase activity – a marker of the gut barrier function – regardless of the type of beer consumed. Therefore, the compounds present in beer seem to outweigh the harmful effects of alcohol on the gut flora.

Benefits linked to polyphenols

The researchers attribute these benefits to polyphenols and isoxanthohumol, an antioxidant substance abundant in beer which reduces the risk of chronic disease. These compounds are found in greater quantities in unfiltered beers, which may have an even greater impact on the health of our gut flora, according to the researchers.

Further work is needed to confirm these results. In the meantime, drink in moderation.

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Over the decades, urbanization and modern infrastructure have reduced our exposure to environmental microorganisms. Improvements in hygiene have protected us from many infectious diseases.

However, a lack of contact with natural bacterial ecosystems in plants, soil, water, etc. is detrimental to our microbiota. What’s more, this absence of nature has consequences for our health: according to scientists, the urban lifestyle (commute-work-sleep routine) favors allergies and diseases with an auto-immune component. Our skin isn’t spared, with urbanization modifying its microbial balance.

However, a touch of nature can help rebalance it. Our skin microbiota is enriched when we walk in urban green spaces, while our children’s microbiota becomes more diversified if they attend green daycare centers. But how can we benefit from plants if we’re locked up in the office eight hours a day?

Green walls for a re-seeded skin microbiota...

A team of Finnish researchers¹ installed air-circulating green walls in university offices. The idea: indoor air is circulated through green plants (philodendrons, Dracaena, ferns, and other plants) using fans. The team compared skin and blood samples from staff working in these green wall offices with those of employees not working between green walls.

The results? Lactobacilli abundance and the diversity of skin proteobacteria, known to help balance the skin microbiota and protect it against harmful microorganisms, rapidly increased in the staff working in green wall offices. In the blood of these employees, the scientists also found a decrease in the level of a pro-inflammatory cytokine (sidenote: Cytokine A small protein involved in communication between cells, especially in the immune system.  Cytokines: Introduction_British Society for Immunology ) and an increase in the level of a cytokine involved in immune response regulation.

...and better quality of life at work

According to the authors of the study, air-circulating green walls balance the moisture in the air and release plant spores or bacteria (including proteobacteria) that settle on the skin. The ability of plants to filter air pollutants may also have a positive effect on the skin microbiota. Either way, green walls are pleasant to look at and potentially beneficial for our health. So while we wait for the results of new studies, should we bring our favorite potted plants to the workplace?

To be continued...

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We already know that taking antibiotics can disrupt gut bacteria. It seems that they are not alone. While most studies focus on the impact of antibiotics on bacteria, few assess the effect on other microorganisms, such as fungi, whose role should not be underestimated. Fungal microbiota or mycobiota dysbiosis has been associated with various disorders and diseases (IBD, celiac disease and colorectal cancer). However, this mycobiota develops progressively in the first few years of life in the same way as bacterial colonization, depending on the mode of delivery, diet or even possible antibiotic treatments.

A study on 37 antibiotic-naive infants

To learn more, researchers followed 37 children for 9.5 months with an average age of 2 months who had never received antibiotics. These infants were hospitalized with respiratory syncytial virus (RSV) infections. Stool samples were taken before, during and after one to four antibiotic treatments (amoxicillin, macrolides) that were prescribed to 21 of them due to complications (otitis media, etc.). The remaining 16 untreated children made up the control group.

At the time of hospitalization (i.e. before treatment), the mycobiome of the 37 children was overwhelmingly dominated by Saccharomyces and to a much lesser extent Malassezia, Candida and Cladosporium.
 

More Candida, diversity and abundance

One to two days after the start of the antibiotic treatment, the abundance of Candida greatly increased in infants on amoxicillin, at the expense of Saccharomyces. An overabundance of Candida continued to be observed more than 6 weeks after the start of treatment.

In addition, antibiotics, which are known to induce a collapse in the diversity and abundance of bacterial microbiota, were associated with an increase in the abundance and diversity of the mycobiota. This appeared within 3 to 5 days of the start of treatment and persisted well beyond that time (> 6 weeks) with the difference most marked in the macrolide group.
 

Are there bacteria that play a regulatory role?

These results strongly suggest that gut bacteria regulate mycobiota on an ongoing basis.  This regulation takes the form of competition for nutrient sources through the production of antifungal compounds by bacteria and, conversely, antibacterial compounds by fungi. As soon as bacteria are affected by an antibiotic, their regulatory role is altered and certain fungi, particularly Candida, are given free rein to develop. As such, gut mycobiota dysbiosis after a single antibiotic treatment could, together with an alteration of gut bacteria, induce the long-term effects of antibiotics on human health.

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Medical research on the impact of antibiotics is hindered by the fact that the studies are generally carried out on polymedicated sick and hospitalized patients. As such, various confounding factors (infection, medications, hospital environment, potential immunosuppression) skew the observations.

The only solution is to conduct prospective studies on healthy outpatient adults, such as this one. American researchers measured the impact of four antibiotic treatments, namely azithromycin (AZM), levofloxacin (LVX), cefpodoxime (CPD) or a combination of CPD and AZM), on the gut microbiota of 20 healthy volunteers randomized into four groups by collecting their stools before, during and two months after the end of treatment (15 collection points in all).

Antibiotic-induced gut dysbiosis 

First finding: antibiotics reduce bacterial abundance and diversity. Depending on the treatment received, changes in abundance differed :

• higher levels of both Bacteroidetes and Clostridium for patients receiving CPD or CPD + AZM at Day 6,
• higher levels of Firmicutes, such as Eubacterium, Ruminococcus and Anaerostipes, for those receiving LVX or AZM.

In addition, AZM (alone or in combination), which has a long half-life, delays the recovery of bacterial abundance, eight bacterial species and some associated metabolic pathways compared to other antibiotics.

A reservoir of resistance genes

Another effect of the antibiotics was the emergence of a long-lasting reservoir of resistance genes in volunteers receiving CPD, AZM and CPD+ AZM treatments, in contrast to those receiving LVX. However, more importantly, the altered composition of their resistome would lead to an increase in three genes (tetO, cfxA, and tet40), two of which do not confer resistance to the antibiotics administered.

Consequently, antibiotic disruption appears to create opportunities for bacteria with broad resistance. For example, Bacteroides that survive CPD treatment, probably via ß-lactam resistance gene cfxA, would create a low-diversity, high-Bacteroides environment, favourable to pathogens such as Enterobacter. Short courses of antibiotics could trigger the acquisition or entrenchment of diverse resistance genes.

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Irritable Bowel Syndrome is a functional gastrointestinal disorder which has depression as one of its most common psychiatric comorbidities. A multi-omic study has recently highlighted the role of the gut microbiota and its metabolites in IBS and associated depression. 

This study³ involved 431 patients from two cohorts:

• one discovery cohort (n=330 patients, 264 with IBS and 66 controls)
• and one validation cohort (n=101 patients, 86 with IBS and 15 controls).

Metagenomic and metabolomic analyses were conducted on stool and serum samples to identify potential biomarkers of the disease.

Serum metabolites as potential IBS markers

Stool analysis revealed only moderate dysbiosis. It appears neither fecal microbiota composition nor fecal metabolites can discriminate IBS patients from healthy individuals. 

However, serum metabolites identified in patients showed significant differences, with greater power to distinguish IBS patients from healthy controls. In total, 726 serum metabolites were identified (compared with only 8 fecal metabolites), including a cluster of fatty acyl-CoAs (a type of fatty acid) enriched in IBS.

_{^{Sources (sidenote: Black CJ, Ford AC. Global burden of irritable bowel syndrome: trends, predictions and risk factors. Nat Rev Gastroenterol Hepatol 2020; 17: 473-86. )}}

Gut bacteria strongly associated with fecal metabolites

Numerous associations (522) between fecal metabolites and gut bacteria were also found. In particular, three species (Odoribacter splanchnicus, Escherichia coli, and Ruminococcus gnavus) were strongly associated with a low abundance of dihydropteroic acid, an intermediate product for folic acid, itself present in very low amounts in IBS patients. Furthermore, among the most significant serum markers in IBS patients were fatty acyl-CoAs, suggesting a deregulation of fatty acid metabolism in IBS.

Deregulated tryptophan/serotonin metabolism correlates with severity of depression 

The results suggest a correlation between tryptophan/serotonin metabolism and the severity of depression associated to IBS. Certain bacteria strains, such as Clostridium nexile or Roseburia inulinivorans, are over-represented in IBS patients with depression and are associated with the presence of certain tryptophan metabolites in serum. The L-tryptophan synthesis pathway is also strongly associated with the severity of depression.

Common and recurrent. This is the profile of urinary tract infections, which tend to affect the same women, 20% to 30% of whom see the infection return up to six times, or even more, per year. Since the gut acts as a reservoir of pathogenic bacteria that travel up the vulva, researchers have been interested in the potential existence of a “gut-bladder” axis, whereby gut dysbiosis is linked to susceptibility to recurrent urinary tract infections (rUTIs).For women suffering from rUTIs is there a specific dynamic in, and between, the gut and bladder? Are microbiota-mediated immunological differences linked to this susceptibility?

To answer this question, a one-year longitudinal clinical study was conducted on 15 women with a history of rUTIs and 16 healthy women. 

Gut dysbiosis and inflammation

The results showed that women with a history of rUTIs had a less diverse gut microbiota, with more Bacteroidetes, and fewer Firmicutes and butyrate-producing bacteria such as Blautia, which are known to regulate inflammation. In fact, blood tests indicate that women susceptible to infection present characteristics of low-grade inflammation. This suggests that susceptibility to rUTIs is partly mediated by a gut-bladder axis, via gut dysbiosis and altered systemic immunity.

The role of E. coli

24 urinary tract infections were reported during the study, all in the rUTI group, and in 82% of the cases, they were caused by E. coli.
However, the dysbiosis observed in the rUTI women did not seem to affect the dynamics of this bacterium: the E. coli populations in the gut and bladder were comparable between the two groups, both in terms of relative abundance and phylogroups. However, no symptoms of urinary tract infection occurred in the healthy controls, suggesting that they alone manage to eliminate E. coli from their bladders. Another finding was that the E. coli strains that cause UTIs often colonize the gut persistently, without being permanently eliminated by repeated exposure to antibiotics. In other words, antibiotics may cure UTIs in the short term by eliminating E. coli from the bladder, but would not protect against recurrences over the long term caused by residual E. coli in the gut.

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What is the gut microbiota? Why are the first 1,000 days of our life so important for its proper development? What is the link to immunity? Why does it play a key role for our health? How does it change over our lifetime?

Want to find out more? Read our articles on this subject.

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BMI 22.45

Prostate cancer is the second most common cancer in men and the fifth deadliest cancer in the world with more than 375,000 deaths in 2020². Despite these figures, prostate cancer is characterized by a very heterogeneous course (in the United States, the 5-year survival rate is estimated at 90%¹).
Today, it is the aggressiveness of the tumor that primarily guides treatment decisions. It is assessed inter alia by the Gleason histopathological score after biopsy, which is an invasive procedure. The identification of urinary markers, which, in combination with clinical data, allows the detection of aggressive forms of the disease, is therefore generating great interest among clinicians.

The urinary microbiota analyzed by molecular imaging and genomics

Studies had already revealed a link between prostate cancer and a specific urinary microbial profile, but also differences in the prostatic bacterial community according to the Gleason score. English researchers therefore turned to the prostate and urinary microbiome, still incompletely characterized, to explore its prognostic potential¹. Using tools such as fluorescence microscopy, anaerobic bacterial culture and genomic sequencing, they analyzed samples of urine and of prostate tissue secretions collected from more than 600 individuals examined in hospital for suspected prostate cancer or hematuria. The subjects were divided into clinical groups and patients diagnosed with prostate cancer stratified according to the D'Amico score.

Anaerobic bacteria linked to tumor progression 

Researchers have demonstrated a significant link between the presence of bacteria in urine and an increased risk of prostate cancer. They also discovered four new bacterial species in the urine samples, the prostatic secretions and the tissues, belonging to the phyla Firmicutes (Fenollariasp. nov. and Peptoniphilus sp.nov), Actinobacteria (Varibaculum sp.nov) and Bacteroidetes (Porphyromonas sp.nov). Five anaerobic species, including three of these new bacteria, were associated with a 2.6-fold increased risk of adverse disease progression, and could serve as potential prognostic biomarkers.

A prognostic, even therapeutic, potential which encourages continued research

The researchers arrived at a hypothesis: these anaerobic bacteria may act on certain metabolic processes.
Such as the conversion of cholesterol into androstenedione, a precursor of testosterone which stimulates tumor growth, or the degradation of citrate, a known marker of prostate cancer aggressiveness. But a causal link between the overrepresentation of these bacteria in patients and disease progression cannot be established at this stage. New research must therefore be undertaken in this respect: if this link is confirmed, a prognostic urine test that is very practical for clinics could be developed. More importantly, targeted antibiotic treatments could control, or even prevent, disease progression.