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Another study has shown health benefits from eating a diet rich in whole grains, as compared to one with lots of refined grains (think bagels, muffins, white bread). Fifty overweight Danish adults were randomly assigned to either a group where all grains eaten were whole grains or a group where all grain products were of refined grains. They did this for 8 weeks, then ate their usual diet for a few weeks (the "washout period"), and then were assigned to the other dietary group for 8 weeks.

They found that eating the diet rich in whole grains resulted in: consuming fewer calories (the whole grains made them feel fuller), losing weight, and a decrease in chronic low-grade inflammation (by measuring blood inflammation markers). The whole grain rye seemed to be especially beneficial. But interestingly, the researchers found that the whole grain diet did not significantly change the gut microbe composition. But they did find that 4 strains of Faecalibacterium prausntzii and one of Prevotella copri increased in abundance after whole grain and decreased after refined grain consumption. F.prausnitzii is a desirable and beneficial keystone species in the gut (here and here).

Other studies show that eating a diet rich in whole grains (rather than refined grains) is associated with a decreased risk of several diseases, including type 2 diabetes and cardiovascular diseases. Bottom line: choose whole grains whenever possible. From Science Daily:

Several reasons why whole grains are healthy

When overweight adults exchange refined grain products -- such as white bread and pasta -- with whole grain varieties, they eat less, they lose weight and the amount of inflammation in their bodies decreases. These are some of the findings of a large Danish study headed by the National Food Institute, Technical University of Denmark. 

The study included 50 adults at risk of developing cardiovascular disease or type 2 diabetes. Blood tests showed that the participants had less inflammation in their bodies when eating whole grains. In particular, it appeared that rye had a beneficial effect on the blood's content of inflammatory markers. Inflammation is the natural response of the body to an infection, but some people have slightly elevated levels of inflammation (so-called low-grade inflammation) even though there is no infection. This is particularly the case in overweight people. In overweight people, an increased level of 'unnecessary' (subclinical) inflammation may lead to increased risk of developing type 2 diabetes.

The study also shows that participants eat less when whole grain products are on the menu -- presumably because whole grain consumption causes satiety. While eating the whole grain diet, participants have generally lost weight. The researchers used DNA sequencing to analyze stool samples from the participants in order to examine whether the different diet types affected the participants' gut bacteria composition. Overall, the analysis did not shown major effects of the dietary grain products on the composition of the gut bacteria. [Original study.]

A while ago I posted the results of studies showing differences in infant  microbiomes (community of microbes) depending on whether the babies were delivered vaginally or by C-section, and also that "vaginal seeding" may eliminate some of these differences. [C-section babies also have a higher incidence of some health issues, such as allergies, asthma, etc.] Well....that research generated a lot of controversy both for and against, and resulted in many women requesting that "vaginal seeding" be done to their babies after they were delivered by C-section. Even the noted microbiome researcher Rob Knight publicly admitted that the procedure was done to his baby after his partner received a C-section.

Vaginal seeding is the process of swabbing the bodies of C-section babies (including the mouth and nose) with a gauze pad containing the vaginal fluids from their mothers in the minutes after birth - so that the baby is exposed to the same maternal microbes as a baby born vaginally (because mothers transmit microbes to the baby as it moves through the birth canal). Initial research showed this made the microbiomes of the C-section babies look a lot like vaginally born babies, especially their skin and oral microbiomes, but whether these differences persist after a few months is unclear.

Now the American College of Obstetrics and Gynecology (ACOG) has come out with a position paper that vaginal seeding should not be done to babies, except as part of an official clinical trial. Their main opposition to the procedure is fear of transmitting pathogenic bacteria or viruses (e.g. group B streptococci, and STDs). The main reasons in support of doing the  vaginal seeding procedure is the body of research finding differences among C-section and vaginally delivered babies (allergies, asthma, etc.), and the concern that at least some of this may be due to lack of  exposure to maternal vaginal microbes during delivery. Instead, ACOG suggests breastfeeding the baby to transmit maternal microbes to the baby to "seed the gut". And if "a patient insists on performing the procedure herself, ACOG recommends ob-gyns have a documented discussion of the potential risks".

As can be expected, there is an outcry and rejection by some (many?) of the ACOG position paper. At least the ACOG paper acknowledges that every woman can make her own decision regarding this issue, even though they may not support it. And absolutely everyone agrees that more research is needed. From Ars Technica:

Doctors warn new parents: Step away from the vaginal fluid swabs

To slather, or not to slather—that is the question that has been roiling doctors, scientists, and new parents recently. And a new ruling by a doctor’s group stands to muck up the debate further. Amid the birth of microbiome research, some scientists have advocated for smearing bacteria-laden vaginal secretions on any newborns who missed out—namely those born via Caesarian section. Scientists keenly hypothesize that such a gooey glaze can “seed” a more-or-less sterile infant with life-long microbial companions. These wee chums may help train an infant's immune system and dodge issues like allergies and asthma later in life. Several studies have indeed found correlations between C-section deliveries and higher risks of those conditions.

In the latest turn to the controversy, the American College of Obstetricians and Gynecologists’ (ACOG) Committee on Obstetric Practice issued a November opinion firmly wiping up the slimy idea. In its opinion, the committee said it: “…does not recommend or encourage vaginal seeding outside of the context of an institutional review board-approved research protocol, and it is recommended that vaginal seeding otherwise not be performed until adequate data regarding the safety and benefit of the process become available.”

The few studies we do have on infant microbiomes provide no clear answers on the significance of an early “seeding” for health. A 2016 review looking at the patterns of microbial communities in the guts of infants in their first year found that C-section babies did show differences in the first three months. However, those differences disappeared by six months. Similarly, a small study of 18 babies also published last year found that vaginal seeding could eliminate microbial differences between vaginally and C-section delivered babies. But the study only looked at the infants' microbiomes in that first month, and the health effects—if any—are unknown.

The most concerning thing about vaginal seeding, the committee argues, is the potential for transmitting pathogens, such as herpes simplex virus, human papilloma virus (HPV), group B streptococci, and Neisseria gonorrhea. .... If a woman insists on the seeding, the committee recommended she be thoroughly tested and informed of the risks—as well as discouraged.

The following is a nice article about a recently published study finding a link between some bacteria commonly found in the mouth and inflammatory bowel diseases (IBD). The researchers found that some strains of oral bacteria are also found in the gut of people with inflammatory bowel diseases.

They theorize that these bacteria make it down to the gut when saliva is swallowed - and for susceptible people this may trigger inflammatory disease. They did a number of experiments to determine that the antibiotic-resistant, inflammation causing species of Klebsiella pneumoniae and Klebsiella aeromobilis could be triggering IBD. These bacteria are able to replace normal colon microbes after antibiotic therapy.

However, it must be noted that other studies also find other microbial differences among those with IBD and healthy people - e.g. low or absent levels of Faecalibacterium prausnitzii, and even fungal and viral differences. From Harvard Magazine:

Gut Health May Begin in the Mouth

Chronic gastrointestinal problems may begin with what is in a patient’s mouth. In a study published Thursday in Science, an international team of researchers—including one from Harvard—reported on strains of oral bacteria that, when swallowed in the 1.5 liters of saliva that people ingest every day, can lodge in the gut and trigger inflammatory bowel conditions like Crohn’s disease and ulcerative colitis.

“For some time now, we’ve noticed that when we look at the microbiome of patients with inflammatory bowel disease, or IBD, we’ve found microbes there that normally reside in the oral cavity,” says study co-author Ramnik Xavier, chief of gastroenterology at Massachusetts General Hospital (MGH)....

Simultaneously, “There’s always been this other search, asking, ‘Are there pathobionts?’”—in other words, microbes that live innocuously in one part of the body but can turn pathogenic when moved to another. “For some time we have been looking for pathobiont organisms for Crohn’s and colitis.”

The researchers believe they have found them: two strains of Klebsiella bacteria, microbes commonly found in the mouth. ....the researchers pinpointed a strain of Klebsiella pneumoniae as the trigger for the immune response. A subsequent experiment using samples from two ulcerative colitis patients turned up another inflammation-causing strain, of Klebsiella aeromobilis

Checking databases of thousands of IBD patients at MGH and the Hospital of the University of Pennsylvania, Xavier and others found that people with inflammatory bowel conditions had significantly more Klebsiella bacteria in their gut microbiome than healthy patients did. Most likely, he explains, oral bacteria, including Klebsiella, traffics through everyone’s gut in the saliva we swallow. Usually it passes through harmlessly; but in people with a genetic susceptibility to IBD that alters the gut microbiome, the Klebsiella has a chance to take hold in the intestine and proliferate, inducing an immune response that causes the disease. 

And there is another twist: Klebsiella bacteria are often extremely resistant to multiple antibiotics. That explains, Xavier says, “why antibiotics have limited value in treating patients with Crohn’s disease and ulcerative colitis....  “Because we also showed in a 2014 paper that patients who took antibiotics—and this has been seen in the old clinical data accumulated before the microbiome was even examined in IBD—that patients who took antibiotics early in the disease had more complicated outcomes.” 

Klebsiella  pneumoniae Credit: Wikipedia

A number of recent studies have suggested that as people age, the community of gut microbes (gut microbiota or gut microbiome) becomes less diverse than in younger people. And note that greater gut microbial diversity is generally viewed as healthy and good. However, now a study done in China finds a different result. The study examined the gut microbes of more than 1000 very healthy people, from ages 3 to over 100, and found that the gut microbial communities were very similar among very healthy people in their mid 30s to over 100 years in age.

Whether this is cause or effect is unknown. But the researchers speculate that the similarities in the gut microbiota among people from their 30s to 100+ is a consequence of an active healthy lifestyle and diet. And it suggests that somehow changing an elderly person's gut microbial community (if it's not "normal") to that of a 30-year-old might help promote health. From Science Daily:

'Ridiculously healthy' elderly have the same gut microbiome as healthy 30-year-olds

In one of the largest microbiota studies conducted in humans, researchers at Western University, Lawson Health Research Institute and Tianyi Health Science Institute in Zhenjiang, Jiangsu, China have shown a potential link between healthy aging and a healthy gut.

With the establishment of the China-Canada Institute, the researchers studied the gut bacteria in a cohort of more than 1,000 Chinese individuals in a variety of age-ranges from 3 to over 100 years-old who were self-selected to be extremely healthy with no known health issues and no family history of disease. The results showed a direct correlation between health and the microbes in the intestine. ....The study, published this month in the journal mSphere, showed that the overall microbiota composition of the healthy elderly group was similar to that of people decades younger, and that the gut microbiota differed little between individuals from the ages of 30 to over 100.

"The main conclusion is that if you are ridiculously healthy and 90 years old, your gut microbiota is not that different from a healthy 30 year old in the same population," said Greg Gloor, the principal investigator on the study and also a professor at Western's Schulich School of Medicine & Dentistry and Scientist at Lawson Health Research Institute. Whether this is cause or effect is unknown, but the study authors point out that it is the diversity of the gut microbiota that remained the same through their study group.

"This demonstrates that maintaining diversity of your gut as you age is a biomarker of healthy aging, just like low-cholesterol is a biomarker of a healthy circulatory system," Gloor said. The researchers suggest that resetting an elderly microbiota to that of a 30-year-old might help promote health. "By studying healthy people, we hope to know what we are striving for when people get sick," said Reid. [Original study.]

Centenarian in Bama County, China. Credit: National Geographic.

Finally - research is being done on ear microbiomes (the community of microbes that live in the ears) and how they differ in people with ear infections and those without ear infections. A recently presented ear microbiome study (at the annual American Academy of Otolaryngology meeting) makes perfect sense, and ties in perfectly with sinus microbiome research. Specifically, that there are microbial communities or microbiomes in the ears, and if the microbial communities go out of whack (dysbiosis) it can cause symptoms (ear infection).

This research reminds me of a wonderful anecdote about ear infections and how they could possibly be treated - an ear wax transplant. From a 2012 article in ENT Today: Restoring Microbial Balance Key to Keeping Sinuses Healthy

Andrew Goldberg, MD, never tires of telling people about how he was outsmarted by a patient while working as a second-year otolaryngology resident at the University of Pittsburgh. Now the director of rhinology and sinus surgery at the University of California San Francisco Medical Center, Dr. Goldberg recalled how he assisted in the examination of a patient with a history of chronic otiti sexterna [ear infection] in one ear. Despite repeated trips to doctors for antibiotics, vinegar washes and drops, the patient’s ear trouble always came back.

Not this time. The doctors assumed that their treatments had finally done the trick, only to be told by the patient that he had likely cured himself by taking earwax from his good ear and sticking it in his bad ear. “I had no idea what that meant. I’m sure that we assumed, at the time, that what he was telling us was nonsense, that he was a little nutty,” Dr. Goldberg said. “We never thought anything more about it.”

The home remedy, however, now seems prescient in light of accumulating research suggesting that microbiomes, or distinct bacterial communities that coexist with us throughout our bodies, may play key roles in maintaining human health. When he began conducting his own microbiome research about five years ago, Dr. Goldberg realized that his former patient may have taken an intact, healthy microbiome and used it to re-inoculate the disrupted bacterial community in his bad ear.

Description of the recently presented study - unfortunately no details were given about specific microbes. From Health Day News at Medline Plus: 'Microbiomes' May Hold Key to Kids' Ear Infections

Recurrent ear infections are the bane of many children -- and the parents who have to deal with their care. Now, research suggests that naturally occurring, "helpful" bacterial colonies in the ear -- called "microbiomes" by scientists -- may help decide a person's vulnerability to these infections. "The children and adults with normal middle ears differed significantly in terms of middle ear microbiomes," concluded a team of Japanese researchers led by Dr. Shujiro Minami of the National Institute of Sensory Organs in Tokyo.

These bacterial ear infections -- called otitis media -- typically start in the middle ear, and 5 out of 6 kids will develop at least one ear infection by the time they turn 3. In the new study, Minami and colleagues wanted to see what role the ear's microbiome might play in these outbreaks. To do so, they took swab samples of the middle ears of 155 children and adults who were having ear surgery due to recurrent ear infections (88 cases) or some other condition.

Among patients with a history of ear infections, the researchers found significant differences in the makeup of microbial communities for people with active ("wet") or inactive ("dry") inflammation. In fact, people whose ear infection was dormant "had similar middle ear microbiomes as the normal [no ear infection] middle ears group," the researchers said. On the other hand, the researchers found that people with an active ear infection had bacterial communities that differed widely from those of people not suffering such outbreaks.

An opinion piece in a journal raises the question of whether having some parasites in the gut is beneficial. We tend to think of parasites as harmful (and yes, some parasite species cause tremendous human suffering and death), but some others seem to exist harmlessly in humans. I'm posting this article because the authors raise the question of whether with progress (sanitation, antibiotics, a Western diet, etc.) we have also lost something beneficial to humans - one-celled organisms (protozoa) that are parasites. They are found in people living in undeveloped countries, but people in developed countries have usually few or none.

Which leads to the question - is the loss of these parasites one of the reasons for the major increase in autoimmune disorders and such diseases as Crohn's disease and colitis? The answers to these questions are unknown at this time, so studies are needed. The authors point out that after millions of years of coevolution, the protists could be providing some beneficial effects to their human hosts - and that they may be part of a normal, healthy gut microbial community (microbiome).

As we know, studies show that in developed Western countries (as compared to undeveloped countries) there is lower microbial diversity in the gut - in other words, with industrialization comes lower bacterial diversity. But... higher microbial diversity is considered beneficial. Normally the human gut has hundreds of microbial species (bacteria, viruses, fungi) living in it and interacting. Some diseases or conditions result in alterations in these microbes, and even "microbial communities being out of whack" (dysbiosis).  The authors of the paper give examples of how the presence of certain non-pathogenic protozoan species in the gut is linked to higher gut microbial diversity and with the presence of bacteria that are anti-inflammatory and beneficial.

KEEP IN MIND: Gut protozoa are one-celled organisms (called protists) that live in the gut as parasites. Numerous protozoa can inhabit the gastrointestinal tract of humans.  According to a Tulane Univ. site "The majority of these protozoa are non-pathogenic commensals, or only result in mild disease", but some of these organisms can cause severe disease under certain conditions. [NOTE: commensal = characterized by a relationship in which one species is benefited while the other is unaffected]. In the following excerpts, a helminth refers to a parasitic worm, such as a fluke, tapeworm, or nematode.

Excerpts from Trends in Parasitology:  Gut Protozoa: Friends or Foes of the Human Gut Microbiota?

The importance of the gut microbiota for human health has sparked a strong interest in the study of the factors that shape its composition and diversity.... We argue that protozoa, like helminths, represent an important factor to take into account when studying the gut microbiome, and that their presence – especially considering their long coevolutionary history with humans – may be beneficial. From this perspective, we examine the relationship between the protozoa and their hosts, as well as their relevance for public health.

The human gut microbiota spans the tree of life and includes bacteria, viruses, and eukaryotes such as fungi, helminths, and protozoa. ...The observation that the gut bacterial microbiome is less diverse in populations from industrialized countries, compared to nonindustrialized countries, has been mostly explained by differences in dietary fiber intake, food sterilization, and the use of antibiotics. Here, we propose that the decreased prevalence of helminths and gut protozoa in industrialized countries is partly responsible for this loss of bacterial diversity.

We argue, based on the knowledge of helminths, that some intestinal protozoa might have beneficial effects on their host through their influence on the gut bacterial microbiome. The role of protozoa in shaping the gut microbiome of healthy individuals remains, however, largely unrecognized. The mechanisms through which protozoa influence the gut bacteria – and the consequences for human health of their absence in developed countries – are poorly understood and call for further attention. 

 The question is therefore whether gut eukaryotes are simply parasites that are detrimental to human health or whether, on the contrary, they could provide, after millions of years of coevolution, some beneficial effects to their hosts. Historically, protozoa and helminths have been considered parasites and assumed to have a detrimental effect on the host organism. Indeed, foodborne and waterborne parasitic diseases are important worldwide, resulting in considerable morbidity and mortality. However, while the focus remains on pathogens that have been investigated from a parasitological point of view, the eukaryotic residents of the gut are often commensal (i.e., benefiting from interacting with the host without affecting it) or even beneficial.

For example, even though some helminths can cause severe illness, infections are often asymptomatic, probably reflecting a long coevolutionary history (since at least 500 million years) and tolerance of these parasites by humans. Similarly, although the best-known protozoan microorganisms found in the human gut are pathogens (i.e., Cryptosporidium spp., Giardia intestinalis, Entamoeba histolytica), it is important to remember that many protozoa, in particular Blastocystis spp., can be found with high prevalence in healthy populations, and are common (and likely ancient) members of healthy microbiomes. Indeed, although protozoan cysts are not as resistant to decay as helminth eggs, they can be found in coprolites, confirming that protozoa, like helminths, were part of our ancestral gut community. 

Interestingly, recent findings also showed that the presence of commensal protozoa (Entamoeba spp. other than Entamoeba histolytica) was strongly associated with increased diversity and various shifts in composition of the gut bacterial microbiota in rural nonindustrialized populations. Higher diversity has also been found in subjects carrying Blastocystis spp., one of the few protozoa to be present at appreciable frequency in industrialized populations. These results suggest similarities between helminths and protozoa in their effect on the gut bacterial microbiome, and raise the possibility of a potentially beneficial effect of (some) protozoa on human health.

Here, we argue that some intestinal protozoan inhabitants could play an important, yet largely unrecognized, role in shaping the gut bacterial microbiota and in maintaining the host–microbe equilibrium, and they should be considered as ‘friends’ of the human gut.

Entamoeba coli - a non-pathogenic species that frequently lives as a commensal parasite in the human gastrointestinal tract. Credit: Wikipedia.

 A study was just published by researchers at the University of California that reviewed the role of Lactobacillus bacteria in a variety of diseases and conditions. What was surprising was that while we generally think of Lactobacillus bacteria as beneficial, some studies suggest that in certain diseases or conditions they may not be. But it is unknown if in those cases whether they're causing harm or why they are there in increased amounts.

Studies have found that Lactobacillus numbers are decreased ("depleted") in: some infectious diseases such as human immunodeficiency virus (HIV), in diarrhea-dominant irritable bowel syndrome (IBS) patients, type 1 diabetes, multiple sclerosis, colorectal cancer, and maternal prenatal stress (resulted in the infant having decreased levels of Lactobacillus bacteria). Lactobacillus levels were found to be either increased or decreased (depending on the study) in: cancer [but breast cancer, head and neck squamous cell cancer had increases in Lactobacillus levels], type 2 diabetes, and obesity. Increased amounts (intestinal "abundance") of Lactobacillus species has been found in: Crohn’s disease (CD) patients and rheumatoid arthritis (RA) patients. Studies also found benefits for consuming probiotics (with varying strains of Lactobacillus) for treating most of these diseases and conditions.

It used to be thought that Lactobacillus species were main species of the gut, but as genetic sequencing tests were developed, it became clear that Lactobacillus species are less than 1% of the bacterial species of the gut - thus a "minor member" of the gut microbiome. But as can be seen in the review study - much is still unknown about Lactobacillus species. What is true for one Lactobacillus species may not apply to another one. Studies find that feeding or nourishing beneficial microbes in the gut is good (e.g., eat foods with lots of fiber), as well as eating foods with lots of naturally occurring microbes (e.g., raw fruits and vegetables, cheeses, and fermented foods).

NOTE: In the following excerpts autochthonous = native (to the gut), and allochthonous - not native (originates elsewhere - such as from ingested probiotics). Excerpts from Current Opinion in Biotechnology:

Intestinal Lactobacillus in health and disease, a driver or just along for the ride?

Similarly, a number of recent publications in which culture independent methods were employed (e.g. 16S rRNA gene amplicon sequencing) identified Lactobacillus as being significantly enriched in the distal gut during either health or disease.....Lactobacillus species have been isolated from the entirety of the human GI tract (oral cavity to feces) as well as the skin and vagina. This genus is estimated to constitute 6% of the total bacterial cell numbers in the human duodenum and approximately 0.3% of all bacteria in the colon..... Lactobacillus can also dominate the human vaginal microbiota (90 to 100% of total bacteria present) and is found on the skin, but in much lower relative abundance.

Only a few out of the >200 known Lactobacillus species  have been consistently and repeatedly associated with the human GI tract. Recently, this number was increased to over 50 Lactobacillus species that were repeatedly detected in the stools of healthy volunteers. The most abundant Lactobacilli included L. casei, L. delbruckeii, L.murinus, L. plantarum, L.rhamnosus, and L. ruminus. Some of these species (e.g. L. rhamnosus and L. murinus) are rarely isolated from environments outside the intestine and are considered gut-autochthonous microorganisms. Other mucosal sites are colonized by distinct species (e.g. L. crispatus in the vagina). 

Both human immunodeficiency virus (HIV)-infected humans and simian immunodeficiency virus (SIV)- infected rhesus macaques harbor reduced numbers of intestinal Lactobacillus..... Several recent animal studies have indicated a broader role for Lactobacillus in prevention and resolution of infectious disease. Tryptophan metabolites (indole aldehydes) produced by indigenous L. reuteri strains activate host aryl hydrocarbon receptors (AHR) to promote gut and vaginal epithelial barrier and antimicrobial responses required for limiting the expansion of Candida albicans, an opportunistic pathogen. Autochthonous Lactobacillus might also have a role in the resolution of infectious disease and recovery of immune homeostasis.

A meta-analysis of reports investigating the fecal microbiomes from IBS patients and healthy subjects concluded Lactobacillus was depleted in diarrhea-dominant, IBS patients..... Consistent with these results, meta-analysis of probiotic intervention studies randomized controlled trials (RCTs)) for treatment of IBS concluded that multi-species probiotics diminish symptoms (abdominal pain, bloating, and flatulence scores). Conversely, intestinal abundance of Lactobacillus and other genera including Bifidobacterium were recently positively correlated with Crohn’s disease (CD)patients .... These findings contrast with ulcerative colitis (UC) in which probiotic Lactobacillus consumption has been with improved clinical symptoms.

The intestinal microbiota of patients with severe and early onset rheumatoid arthritis (RA) were shown to have increased proportions of L. salivarius, L. ruminus, and L. iners when compared to healthy, age-matched individuals..... These results are in opposition to recent RCTs of probiotics in RA patients.... Such findings might indicate species or strain-specific differences between autochthonous and allochthonous Lactobacillus on RA disease activity.

There are conflicting reports on the association of intestinal Lactobacillus with obesity in humans..... Moreover, metaanalysis of RCT studies found that probiotic Lactobacillus improved weight management outcomes in obese adults. Consumption of yogurt and other dairy products fermented by Lactobacillus is also correlated with protection from T2D and obesity. Because Lactobacillus species appear to be either associated with weight gain or weight loss, the disparate findings among obese individuals might be due to genetic differences among the lactobacilli. Strain and species distinctions could result in variations in carbohydrate metabolism and production of fermentation end-products, such as lactate.

In a systematic review of thirty-one studies, Lactobacillus along with a limited number of butyrogenic genera were consistently diminished in colorectal cancer patients. Preventative and therapeutic roles of Lactobacillus in cancer are supported in studies with preclinical, rodent models, including a recently study in which a multi-strain probiotic altered Th-cell polarization away from Th17 cells in a mouse model of hepatocellular carcinoma. However, Lactobacillus might not always be beneficial in certain extra-intestinal sites as shown by the higher levels of Lactobacillus in malignant breast cancer compared to benign-disease tissues. There was also a positive association between the levels of this genus in the oral microbiome and head and neck squamous cell carcinoma.

Image result for psoriasis wikipediaCould probiotics have a role to play in the treatment of psoriasis? A recent analysis and review of studies suggests that they might. Psoriasis is a non-contagious, chronic disease affecting about 2 to 4% of the population, and which is characterized by patches of abnormal skin. These skin patches are typically red, itchy, and scaly, and can cover small areas to covering the entire body. There is no cure for psoriasis, but various treatments can help control the symptoms, such as steroid creams, vitamin D3 cream, ultraviolet light, and immune system suppressing medications. 

What did the researchers find? They said that "new evidence suggests that the microbiome may play a pathogenic role in psoriatic disease" - meaning the community of microbes (microbiome) may be involved in this disease. There is dysbiosis of the skin microbiome (microbial community is out of whack) in areas of skin lesions or patches. Areas of skin lesions had a different microbiome ("lesional psoriatic microbiome") compared to healthy skin - and in these skin lesions or patches some microbial species increase which leads to a decrease or elimination of others. Not just differences in bacteria, but also in fungi and viruses.

in psoriasis the microbial community of the gut is also out of whack (dysbiosis of the gut microbiome). And the gut microbiome is different in those with psoriasis limited to just skin patches, and those with complications of psoriasis (e.g., psoriatic arthritis) - and several studies found that these shifts in the gut microbiome occurred before the psoriatic complications became evident. That suggests that probiotics might help. But which ones?

The researchers state: "Other changes observed in gut microbiome studies include a decrease in Actinobacteria. This may suggest a protective role of Actinobacteria, a phylum which includes Bifidobacterium species that have been shown to reduce intestinal inflammation, suppress autoimmunity, and induce Tregs." They go on to state that one 2013 study by Groeger et al demonstrated that eating Bifidobacteria infantis 35,624 for 6–8 weeks in a randomized, double-blind, placebo-controlled clinical trial reduced inflammatory markers (plasma CRP and TNF-a) in psoriasis patients. Bifidobacterium species, including B. infantis, are commonly found in many multi-strain supplements. So I wonder, what happens if people with psoriasis take them over an extended period? Will the skin psoriasis skin patches improve? This is currently unknown. But...If you've had success with probiotics as a  psoriasis treatment - please let me know. What microbes? And for what symptoms of psoriasis?

From Current Dermatology Reports : The Role of the Skin and Gut Microbiome in Psoriatic Disease

Our review of studies pertaining to the cutaneous microbiome showed a trend towards an increased relative abundance of Streptococcus and a decreased level of Propionibacterium in psoriasis patients compared to controls. In the gut microbiome, the ratio of Firmicutes and Bacteroidetes was perturbed in psoriatic individuals compared to healthy controls. Actinobacteria was also relatively underrepresented in psoriasis patients relative to healthy individuals.

Summary: Although the field of the psoriatic microbiome is relatively new, these first studies reveal interesting differences in microbiome composition that may be associated with the development of psoriatic comorbidities and serve as novel therapeutic targets.

Image result for psoriasis medscape  Psoriasis.  Credit: Medscape

 Did you know that you exchange some skin microbes with the person you live with? A recent study looked at the microbial communities on different regions of the skin of 10 heterosexual couples living together. The researchers found that cohabitation resulted in microbes being shared, but that a person's own microbes were more important, as well as their biological sex and what region of the skin was sampled. In other words - people's microbes look more like their own microbiome than that of their significant other.

Skin is the largest organ of the body, and it is a protective barrier between a person and its environment. The skin contains a diverse microbial community of largely beneficial and benign microorganisms, and also protects the body from microorganisms with the potential to cause disease. Studies show that between one million and one billion microorganisms (bacteria, fungi, viruses, archaea, etc.) each square centimeter of skin. Humans shed over one million biological particles per hour.

The researchers also found that female skin microbial communities were more diverse than that of males, and that spending more time outdoors, owning pets, and drinking less alcohol (or none) were all associated with higher levels of microbial skin diversity. They found that a person's biological sex could be determined 100% of the time from microbes on the inner thigh skin. The skin of the feet had the most matched microbes among couples - perhaps when they walk barefoot on floors and the shower, they are sharing microbes (from skin particles that had been shed). From Science Daily:

Not under the skin, but on it: Living together brings couples' microbiomes together

Couples who live together share many things: Bedrooms, bathrooms, food, and even bacteria. After analyzing skin microbiomes from cohabitating couples, microbial ecologists at the University of Waterloo, in Canada, found that people who live together significantly influence the microbial communities on each other's skinThe commonalities were strong enough that computer algorithms could identify cohabitating couples with 86 percent accuracy based on skin microbiomes alone, the researchers report this week in mSystems, an open-access journal of the American Society for Microbiology.

However, the researchers also reported that cohabitation is likely less influential on a person's microbial profile than other factors like biological sex and what part of the body is being studied. In addition, the microbial profile from a person's body usually looks more like their own microbiome than like that of their significant other. "You look like yourself more than you look like your partner," says Ashley Ross, who led the study while a graduate student in the lab of Josh Neufeld.

Neufeld and Ross, together with Andrew Doxey, analyzed 330 skin swabs collected from 17 sites on the participants, all of whom were heterosexual and lived in the Waterloo region. Participants self-collected samples with swabs, and sites included the upper eyelids, outer nostrils, inner nostrils, armpits, torso, back, navel, and palms of hands. Neufeld says the study is the first to identify regions of skin with the most similar microbiomes between partners. They found the strongest similarities on partners' feet. "In hindsight, it makes sense," says Neufeld. "You shower and walk on the same floor barefoot. This process likely serves as a form of microbial exchange with your partner, and also with your home itself." 

The analyses revealed stronger correlations in some sites than in others. For example, microbial communities on the inner thigh were more similar among people of the same biological sex than between cohabiting partners. Computer algorithms could differentiate between men and women with 100 percent accuracy by analyzing inner thigh samples alone, suggesting that a person's biological sex can be determined based on that region, but not others. The researchers also found that the microbial profiles of sites on a person's left side -- like hands, eyelids, armpits, or nostrils -- strongly resemble those on their right side. Of all the swab sites, the least microbial diversity was found on either side of the outer nose[Original study.]

Image result for Thaumarchaeota Something new to add to the list of what is in our skin microbiome - the community of microbes (bacteria, fungi, viruses) living on our skin. It turns out we also have archaea, which are single-celled microorganisms that are thought to be beneficial.

The human skin microbiome acts as a barrier protecting our body from pathogens and other environmental influences. The most common archaea found in the samples (from the chest area of 51 volunteers between the ages of 1 to 75 years) is called Thaumarchaeota. The results reveal that archaea are more abundant in people older than 60 years or younger than 12 years (as compared to middle-aged persons). But there were no differences between males and females. From Science Daily:

What's on your skin? Archaea, that's what

It turns out your skin is crawling with single-celled microorganisms -- and they're not just bacteria. A study by the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and the Medical University of Graz has found that the skin microbiome also contains archaea, a type of extreme-loving microbe, and that the amount of it varies with ageThe researchers conducted both genetic and chemical analyses of samples collected from human volunteers ranging in age from 1 to 75. They found that archaea (pronounced ar-KEY-uh) were most abundant in subjects younger than 12 and older than 60

In addition to the influence of age, they found that gender was not a factor but that people with dry skin have more archaea. "Archaea might be important for the cleanup process under dry skin conditions," said Moissl-Eichinger. "The results of our genetic analysis (DNA-based quantitative PCR and next-generation sequencing), together with results obtained from infrared spectroscopy imaging, allowed us to link lower levels of sebum [the oily secretion of sebaceous glands] and thus reduced skin moisture with an increase of archaeal signatures."

It was not until the 1970s that scientists realized how different archaea were from bacteria, and they became a separate branch on the tree of life -- the three branches being Bacteria, Archaea, and Eukarya (which includes all plants and animals). Archaea are commonly found in extreme environments, such as hot springs and Antarctic ice. Nowadays it is known that archaea exist in sediments and in Earth's subsurface as well, but they have only recently been found in the human gut and linked with the human microbiome.

Their study focused on Thaumarchaeota, one of the many phyla of archaea, as little evidence of the others was found in the pilot study. "We know that Thaumarchaeota are supposed to be an ammonia-oxidizing microorganism, and ammonia is a major component of sweat, which means they might play a role in nitrogen turnover and skin health," Holman said. .... the team also correlated archaeal abundance with skin dryness, as middle-aged persons have higher sebum levels and thus moister skin than the elderly. So far, most archaea are known to be beneficial rather than harmful to human health. They may be important for reducing skin pH or keeping it at low levels, and lower pH is associated with lower susceptibility to infections.  [Original study.]

Image result for Thaumarchaeota Thaumarchaeota archaea. These single-celled organisms have just one membrane sac that encloses their bodies. Credit: Univ. of Washington