Skip to content

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.

OK, this study was done in mice, but it's the kind of study results that everyone hopes (and thinks) is also true for humans. So drink a nice cuppa black tea and think about how you're increasing bacteria in the gut associated with weight loss.

Black tea (as well as green tea) has polyphenols that stimulate the growth of gut bacterium and the formation of short-chain fatty acids. By the way, the mice were given decaffeinated tea extracts, so theoretically both decaf and caffeinated tea should have benefits. The big question though is - will drinking black tea daily actually result in weight loss? From Medical Xpress:

Black tea may help with weight loss, too

UCLA researchers have demonstrated for the first time that black tea may promote weight loss and other health benefits by changing bacteria in the gut. In a study of mice, the scientists showed that black tea alters energy metabolism in the liver by changing gut metabolites. The research is published in the European Journal of Nutrition. The study found that both black and green tea changed the ratio of intestinal bacteria in the animals: The percentage of bacteria associated with obesity decreased, while bacteria associated with lean body mass increased.

Previous studies indicated that chemicals in green tea called polyphenols are absorbed and alter the energy metabolism in the liver. The new findings show that black tea polyphenols, which are too large to be absorbed in the small intestine, stimulate the growth of gut bacterium and the formation of short-chain fatty acids, a type of bacterial metabolites that has been shown to alter the energy metabolism in the liver.

The researchers also collected samples from the mice's large intestines (to measure bacteria content) and liver tissues (to measure fat deposits). In the mice that consumed either type of tea extract, there was less of the type of bacteria associated with obesity and more of the bacteria associated with lean body mass. However, only the mice that consumed black tea extract had an increase in a type of bacteria called Pseudobutyrivibrio, which could help explain the difference between how black tea and green tea change energy metabolism.

The new study also concluded that both green tea and black tea have different effects on liver metabolism. According to Henning, the molecules in green tea are smaller and can more readily be absorbed into the body and reach the liver directly, while black tea molecules are larger and stay in the intestine rather than being absorbed. When black tea molecules stay in the intestinal tract, they enhance the growth of beneficial bacteria and the formation of microbial metabolites involved in the regulation of energy metabolism. [Original study.]

Another article was published this month raising the issue of whether Alzheimer's disease is caused by a microbe - which can explain why all the medicines and experimental drugs aimed at treating the "tangles" or amyloid plaques in the brain are not working as a treatment (because that's the wrong approach). The microbe theory of Alzheimer's disease has been around for decades, but only recently is it starting to be taken seriously. Some of the microbes found in patients with Alzheimer's disease (from analyses of both normal brains and Alzheimer patient brains after death): fungi, Borrelia burgdorferi (Lyme disease), herpes simplex virus Type 1 (HSV1), and Chlamydia pneumoniae.

The general hypotheses seem to be that Alzheimer’s disease is caused by infection, but it isn't linked to any one pathogenic microbe.  Instead, the evidence seems to support that "following infection, certain pathogens gain access to brain, where immune responses result in the accumulation of amyloid-β, leading to plaque formation". So the microbes act as "triggers" for Alzheimer's disease - the microbes get into the brain, and immune responses somehow eventually result in the amyloid plaques and Alzheimer's disease. From The Scientist:

Do Microbes Trigger Alzheimer’s Disease?

In late 2011, Drexel University dermatology professor Herbert Allen was astounded to read a new research paper documenting the presence of long, corkscrew-shape bacteria called spirochetes in postmortem brains of patients with Alzheimer’s disease. Combing data from published reports, the International Alzheimer Research Center’s Judith Miklossy and colleagues had found evidence of spirochetes in 451 of 495 Alzheimer’s brains. In 25 percent of cases, researchers had identified the spirochete as Borrelia burgdorferi, a causative agent of Lyme disease. Control brains did not contain the spirochetes.

Allen had recently proposed a novel role for biofilms—colonies of bacteria that adhere to surfaces and are largely resistant to immune attack or antibiotics—in eczema....  Allen knew of recent work showing that Lyme spirochetes form biofilms, which led him to wonder if biofilms might also play a role in Alzheimer’s disease. When Allen stained for biofilms in brains from deceased Alzheimer’s patients, he found them in the same hippocampal locations as amyloid plaquesToll-like receptor 2 (TLR2), a key player in innate immunity, was also present in the same region of the Alzheimer’s brains but not in the controls. He hypothesizes that TLR2 is activated by the presence of bacteria, but is locked out by the biofilm and damages the surrounding tissue instead.

Spirochetes, common members of the oral microbiome, belong to a small set of microbes that cross the blood-brain barrier when they’re circulating in the blood, as they are during active Lyme infections or after oral surgery. However, the bacteria are so slow to divide that it can take decades to grow a biofilm. This time line is consistent with Alzheimer’s being a disease of old age, Allen reasons, and is corroborated by syphilis cases in which the neuroinvasive effects of spirochetes might appear as long as 50 years after primary infection.

Allen’s work contributes to the revival of a long-standing hypothesis concerning the development of Alzheimer’s. For 30 years, a handful of researchers have been pursuing the idea that pathogenic microbes may serve as triggers for the disease’s neuropathology..... In light of continued failures to develop effective drugs, some researchers, such as Harvard neurobiologist Rudolph Tanzi, think it’s high time that more effort and funding go into alternative theories of the disease. “Any hypothesis about Alzheimer’s disease must include amyloid plaques, tangles, inflammation—and, I believe, infection.”

Herpes simplex virus type 1 (HSV1) can acutely infect the brain and cause a rare but very serious encephalitis. In the late 1980s, University of Manchester molecular virologist Ruth Itzhaki noticed that the areas of the brain affected in HSV1 patients were the same as those damaged in patients with Alzheimer’s disease. Knowing that herpes can lie latent in the body for long periods of time, she began to wonder if there was a causal connection between the infection and the neurodegenerative disorder.

Around the same time, neuropathologist Miklossy, then at the University of Lausanne in Switzerland, was detailing the brain damage caused by spirochetes—both in neurosyphilis and neuroborrelia, a syndrome caused by Lyme bacteria. She happened upon a head trauma case with evidence of bacterial invasion and plaque formation, and turned her attention to Alzheimer’s. She isolated spirochetes from brain tissue in 14 Alzheimer’s patients but detected none in 13 age-matched controls. In addition, monoclonal antibodies that target the amyloid precursor protein (APP)—which, when cleaved, forms amyloid-β—cross-reacted with the spirochete species found, suggesting the bacteria might be the source of the protein.

Meanwhile, in the U.S., a third line of evidence linking Alzheimer’s to microbial infection began to emerge. While serving on a fraud investigation committee, Alan Hudson, a microbiologist then at MCP-Hahnemann School of Medicine in Philadelphia, met Brian Balin.... Soon, Balin began to send Hudson Alzheimer’s brain tissue to test for intracellular bacteria in the Chlamydia genus. Some samples tested positive for C. pneumoniae: specifically, the bacteria resided in microglia and astrocytes in regions of the brain associated with Alzheimer’s neuropathology, such as the hippocampus and other limbic system areas. Hudson had a second technician repeat the tests before he called Balin to unblind the samples. The negatives were from control brains; the positives all had advanced Alzheimer’s disease. "We were floored,” Hudson says.

Thus, as early as the 1990s, three laboratories in different countries, each studying different organisms, had each implicated human pathogens in the etiology of Alzheimer’s disease. But the suggestion that Alzheimer’s might have some microbial infection component was still well outside of the theoretical mainstream. Last year, Itzhaki, Miklossy, Hudson, and Balin, along with 29 other scientists, published a review in the Journal of Alzheimer’s Disease to lay out the evidence implicating a causal role for microbes in the disease.

The microbe theorists freely admit that their proposed microbial triggers are not the only cause of Alzheimer’s disease. In Itzhaki’s case, some 40 percent of cases are not explained by HSV1 infection. Of course, the idea that Alzheimer’s might be linked to infection isn’t limited to any one pathogen; the hypothesis is simply that, following infection, certain pathogens gain access to brain, where immune responses result in the accumulation of amyloid-β, leading to plaque formation.

Image result for chlamydia wikipediaThe annual Sexually Transmitted Disease Surveillance Report was released today by the US Centers for Disease Control and Prevention (CDC) and the news wasn't good. More than two million cases of chlamydia, gonorrhea and syphilis were reported in the United States in 2016 - the highest number ever. But the CDC acknowledges that the actual numbers are far higher - that most cases of STDs are not reported to the CDC. The CDC estimates that there are actually 20 million new STDs in the U.S. each year, including other sexually transmitted diseases such as genital herpes and human papillomavirus, and half of these are among young people ages 15 to 24 years.

The report discusses the four STDs (sexually transmitted diseases) that are reported to the CDC. The 4th one is chancroid, but there were only 7 cases reported last year. Most of the new cases of STDs involved chlamydia, a bacterial infection that affects both men and women - about 1.6 million cases were reported to the CDC. Gonorrhea also increased among men and women last year, but the steepest rise was among men, especially among men who have sex with men (MSM). The CDC is especially concerned about the threat of gonorrhea becoming resistant to all treatments. Untreated STDs have serious health consequences (e.g. infertility, still-birth in infants)

This report stresses the need for STD screening and treatment, especially among pregnant women (make it part of prenatal care). There is also a need for STD education, and greater use of condoms to reduce risk of STDs. The CDC has a page on STD prevention (practice abstinence, use condoms, have fewer sexual partners and exclusive relationships, get the HPV vaccine, and talk with your partner about safe sex).  Excerpts from CDC:

STDs at record high, indicating urgent need for prevention

More than two million cases of chlamydia, gonorrhea and syphilis were reported in the United States in 2016, the highest number ever, according to the annual Sexually Transmitted Disease Surveillance Report released today by the Centers for Disease Control and Prevention (CDC).

The majority of these new diagnoses (1.6 million) were cases of chlamydia. There were also 470,000 gonorrhea cases and almost 28,000 cases of primary and secondary syphilis – the most infectious stages of the disease. While all three of these STDs can be cured with antibiotics, if left undiagnosed and untreated, they can have serious health consequences, including infertility, life-threatening ectopic pregnancy, stillbirth in infants, and increased risk for HIV transmission.

While young women continue to bear the greatest burden of chlamydia (nearly half of all diagnosed infections), surges in syphilis and gonorrhea are increasingly affecting new populations.

Syphilis rates increased by nearly 18 percent overall from 2015 to 2016. The majority of these cases occur among men – especially gay, bisexual and other men who have sex with men (MSM) – however, there was a 36 percent increase in rates of syphilis among women, and a 28 percent increase in syphilis among newborns (congenital syphilis) during this period. More than 600 cases of congenital syphilis were reported in 2016, which has resulted in more than 40 deaths and severe health complications among newborns. The disease is preventable through routine screening and timely treatment for syphilis among pregnant women.

While gonorrhea increased among men and women in 2016, the steepest increases were seen among men (22 percent). Research suggests that a large share of new gonorrhea cases are occurring among MSM. These trends are particularly alarming in light of the growing threat of drug resistance to the last remaining recommended gonorrhea treatment.

Image result for chlamydia wikipedia Chlamydia trachomatis (chlamydia) - in brown. Credit: Wikipedia

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.

A number of people contacting me have indicated that living in a house or apartment with a mold problem led to their chronic sinusitis. And it wasn't the dreaded toxic black mold (varieties of mold which can cause serious neurological symptoms), but common molds that triggered their inflammatory reactions, respiratory symptoms, allergies, and eventually chronic sinusitis. All due to excessive mold exposure.

This summer's flooding caused by hurricanes and tropical storms will result in major mold growth in residences after the water recedes. What will be the health consequences? Article excerpts about mold (and with impressive photos) from The Atlantic:

The Looming Consequences of Breathing Mold

But the impact of hurricanes on health is not captured in the mortality and morbidity numbers in the days after the rain. This is typified by the inglorious problem of mold. Submerging a city means introducing a new ecosystem of fungal growth that will change the health of the population in ways we are only beginning to understand. The same infrastructure and geography that have kept this water from dissipating created a uniquely prolonged period for fungal overgrowth to take hold, which can mean health effects that will bear out over years and lifetimes.

The documented dangers of excessive mold exposure are many. Guidelines issued by the World Health Organization note that living or working amid mold is associated with respiratory symptoms, allergies, asthma, and immunological reactions. The document cites a wide array of “inflammatory and toxic responses after exposure to microorganisms isolated from damp buildings, including their spores, metabolites, and components,” as well as evidence that mold exposure can increase risks of rare conditions like hypersensitivity pneumonitis, allergic alveolitis, and chronic sinusitis.

Twelve years ago in New Orleans, Katrina similarly rendered most homes unlivable, and it created a breeding ground for mosquitoes and the diseases they carry, and caused a shortage of potable water and food. But long after these threats to human health were addressed, the mold exposure, in low-income neighborhoods in particular, continued. The same is true in parts of Brooklyn, where mold overgrowth has reportedly worsened in the years since Hurricane Sandy. In the Red Hook neighborhood, a community report last October found that a still-growing number of residents were living in moldy apartments.

The highly publicized “toxic mold”—meaning the varieties that send mycotoxins into the air, the inhaling of which can acutely sicken anyone—causes most concern right after a flood. In the wake of Hurricane Matthew in South Carolina last year, sludge stood feet deep in homes for days. As it receded, toxic black mold grew. In one small community, Nichols, it was more the mold than the water itself that left the town’s 261 homes uninhabitable for months.

The more insidious and ubiquitous molds, though, produce no acutely dangerous mycotoxins but can still trigger inflammatory reactions, allergies, and asthma. The degree of impact from these exposure in New Orleans after Hurricane Katrina is still being studied.

Molds also emit volatile chemicals that some experts believe could affect the human nervous system. Among them is Joan Bennett, a distinguished professor of plant biology and pathology at Rutgers University, who has devoted her career to the study of fungal toxins. She was living in New Orleans during the storm, and she recalls that while some health experts were worried about heavy-metal poisoning or cholera, she was worried about fungus.

The smell of the fungi in her house got so strong after the flooding that it gave her headaches and made her nauseated. As she evacuated, wearing a mask and gloves, she took samples of the mold along with her valued possessions. Her lab at Rutgers went on to report that the volatile organic compounds emitted by the mold, known as mushroom alcohol, had some bizarre effects on fruit flies. For one, they affected genes involved in handling and transporting dopamine in a way that mimicked the pathology of Parkinson’s disease in humans. “More biologists ought to be looking at gas-phase compounds, because I’m quite certain we’ll find a lot of unexpected effects that we’ve been ignoring,” said Bennett.

 Mold in ceiling.  Credit: CDC

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

 Could something as simple as giving a probiotic and a sugar for 7 days prevent sepsis in babies? Sepsis is a life-threatening infection that is a HUGE problem in developing countries such as India. It is a major cause of death in babies throughout the world, even with antibiotic treatment. So this new research (done in India) finding that giving newborn babies a probiotic plus the sugar fructooligosaccharide (FOS) for only one week had the result of lowering the incidence of sepsis and death by 40%, and also infections is huge news. A game changer.

The researchers found that the strain given to the babies was very important. They first tried Lactobacillus GG and Lactobacillus sporogenes, but didn't have success. But a strain of Lactobacillus plantarum was amazingly effective. They gave it together with a sugar - fructooligosaccharide (FOS) - which together worked as a synbiotic. Synbiotics are combinations of probiotics with an FOS supplement that promotes growth and colonization of the beneficial bacteria. FOS (which is naturally found in breast milk and such plants as onion, chicory, garlic, asparagus, banana, artichoke, agave, leeks, wheat, barley), is food for the probiotic bacteria.

It must be pointed out that other studies have tried other probiotics in the prevention of sepsis, but have not been successful. Probiotics that did not work work in other studies were Streptococcus thermophilus, Bifidobacterium infantis, Bifidobacterium lactis, and Bifidobacterium breve. However, they did not also use prebiotic supplements (the FOS) - just the probiotic alone - and studied premature or low birth weight babies (while this study focused on healthy babies of approximately normal weight.) This is why research now needs to be done looking at other groups of babies. From Medical Xpress:

Study shows probiotics can prevent sepsis in infants

A research team at the University of Nebraska Medical Center College of Public Health has determined that a special mixture of good bacteria in the body reduced the incidence of sepsis in infants in India by 40 percent at a cost of only $1 per infant...... The special mixture included a probiotic called Lactobacillus plantarum ATCC-202195 combined with fructo-oligosaccharide (FOS), an oral synbiotic preparation developed by Dr. Panigrahi.

Probiotics are live bacteria and yeasts that are good for your health, especially your digestive system. Synbiotics are combinations of probiotics with an FOS supplement that promotes growth and sustains colonization of the probiotic strain. FOS, naturally found in breast milk and such plants as onion, chicory, garlic, asparagus, banana, artichoke and others, is food for the probiotic bacteria.

Sepsis is a severe complication of bacterial infection that results in around one million infant deaths worldwide each year, mostly in developing countries. It occurs when the immune system stops fighting germs and begins to turn on itself and can lead to tissue damage, organ failure and death. It is estimated that 40 percent of patients with severe sepsis in developing countries do not survive.

The team enrolled more than 4,500 newborns from 149 villages in the Indian province of Odisha and followed them for their first 60 days, the most critical period when they get sick and die. During their first days of life, the newborns were administered the oral preparation for seven days. Results of the randomized, double-blind, placebo-controlled study showed that sepsis and deaths in the first two months of infancy were reduced by 40 percent, more than twice the anticipated reduction of 20 percent. The synbiotic treatment also lowered respiratory tract infections. The effectiveness demonstrated in Dr. Panigrahi's study was so successful the study was halted early. 

An interesting article about this research from The Atlantic: At Last, a Big, Successful Trial of Probiotics