First large-scale analysis completed of intra-species genetic variation in gut’s resident organisms
HSNewsBeat | Updated 9:00 AM, 01.29.2015|
Posted in: Research
First large-scale analysis completed of intra-species genetic variation in gut’s resident organisms
HSNewsBeat | Updated 9:00 AM, 01.29.2015|
Posted in: Research
From the 22 January 2015 press release
New Rochelle, NY, January 21, 2015–The hundred trillion bacteria living in an adult human–mostly in the intestines, making up the gut microbiome–have a significant impact on behavior and brain health. The many ways gut bacteria can impact normal brain activity and development, affect sleep and stress responses, play a role in a variety of diseases, and be modified through diet for therapeutic use are described in a comprehensive Review article in Journal of Medicinal Food, a peer-reviewed journal from Mary Ann Liebert, Inc., publishers. The paper is available free on the Journal of Medicinal Food website until February 21, 2015.
In “The Gut Microbiome and the Brain”, Leo Galland, Foundation for Integrated Medicine (New York, NY), presents the most up-to-date understanding of the relationship between the proteins produced by intestinal bacteria and the human central nervous system. The author explores the various mechanisms through which the microbiome can influence the brain: by stimulating and over-stimulating the immune system, producing neurotoxic agents, releasing hormones or neurotransmitters identical to those made by the human body, or through direct neuronal stimulation that sends signals to the brain.
“The microbiome has become a hot topic in many branches of medicine, from immune and inflammatory diseases, such as Crohn’s and IBD to cardiovascular diseases,” says Co-Editor-in-Chief Sampath Parthasarathy, MBA, PhD, Florida Hospital Chair in Cardiovascular Sciences, University of Central Florida, Orlando. “Scientists are not only aware of the ‘good’ and the ‘bad’ microbes in the gut but are becoming increasingly aware of how they could alter the metabolism beyond gut.”
Can be downloaded for free!
A comprehensive reference with helpful charts and personal stories. The guide covers major diseases, aging mental health, reproductive health, nutrition and alternative medicine. It also provices advice on common screening tests and immunizations you may need. (Previous item number: 107W)
Source: U.S. Department of Health and Human Services
In recent years, it has become increasingly clear that many diseases are triggered or maintained by changes in bacterial communities in the gut. However, the general view up into now has been rather simple: bacteria stimulate the immune system, leading to inflammation or autoimmune disorders in a single direction.
Now, in work published in Immunity, scientists led by Sidonia Fagarasan from the RIKEN Center for Integrative Medical Science in Japan have painted a more complex picture: the gut immune system does not simply prevent the influx of pathogens, but is actively involved in the maintenance of a rich and healthy community of gut bacteria. They propose that faults in the immune regulation lead to changes in the bacterial community that in turn feed back into the immune system.
In the study, the group demonstrated that the regulation by immune T cells of immunoglobulin A (IgA), an antibody that plays a key role in immunity in the gut, is critical for the maintenance of rich bacterial communities in mammal guts.
They began by studying mice with various immune deficiencies and attempted to restore the mice by providing the missing components. They monitored the bacterial communities in the mice’s guts with or without the reconstitutions and evaluated the flow of information between the immune system and bacteria. They discovered that the precise control of IgA production by regulatory T cells is critical for keeping a rich and balanced bacterial community.
To investigate how bacteria feed back to the host, they looked at germ-free mice (mice born and maintained sterile in special incubators) and young pups that had been transplanted with different bacterial communities (either by injection of bacteria or by painting the fur with fecal bacteria extracts from normal or immune-deficient mice). They discovered that the immune system “sees” and responds differently to different bacterial communities. Rich and balanced bacterial communities seem to be perceived as “self” and induce a quick maturation of the immune system and gut responses (induction of regulatory T cells and IgA), while a poor and unbalanced bacterial community is apparently perceived as “non-self” and induces responses aimed at eliminating it (T cells with inflammatory properties and IgG or IgE responses).
According to Sidonia Fagarasan, who led the work, “This study should have an impact on the way we understand immune-related disorders associated with bacteria dysbiosis in the gut. In order to reestablish a healthy state we need to interfere not only with the bacteria, by providing probiotics or through fecal transplantation, but also with the immune system, by correcting the faults caused either by inherited deficiencies or by aging.”
“It was surprising,” she continues, “to see how the reconstitution of T cell-deficient mice with a special regulatory T cell type leads to dramatic changes in gut bacterial communities. It was spectacular to see how the immune system perceives and reacts to different bacteria communities. It gives us hopes that with a better knowledge of the symbiotic relationships between the immune system and bacteria in the gut, we could intervene and induce modifications aiming to reestablish balance and restore health.”
Excerpts from the 21 February 2014 article
The bacteria in our guts can influence the working of the mind, says Frank Swain. So could they be upgraded to enhance brainpower?
I have some startling news: you are not human. At least, by some counts. While you are indeed made up of billions of human cells working in remarkable concert, these are easily outnumbered by the bacterial cells that live on and in you – your microbiome. There are ten of them for every one of your own cells, and they add an extra two kilograms (4.4lbs) to your body.
Far from being freeloading passengers, many of these microbes actively help digest food and prevent infection. And now evidence is emerging that these tiny organisms may also have a profound impact on the brain too. They are a living augmentation of your body – and like any enhancement, this means they could, in principle, be upgraded. So, could you hack your microbiome to make yourself healthier, happier, and smarter too?
“Diet is perhaps the biggest factor in shaping the composition of the microbiome,” he says. A study by University College Cork researcherspublished in Nature in 2012 followed 200 elderly people over the course of two years, as they transitioned into different environments such as nursing homes. The researchers found that their subjects’ health – frailty, cognition, and immune system – all correlated with their microbiome. From bacterial population alone, researchers could tell if a patient was a long-stay patient in a nursing home, or short-stay, or living in the general community. These changes were a direct reflection of their diet in these different environments. “A diverse diet gives you a diverse microbiome that gives you a better health outcome,” says Cryan.
Beyond a healthy and varied diet, though, it still remains to be discovered whether certain food combinations could alter the microbiome to produce a cognitive boost. In fact, Cryan recommends that claims from probiotic supplements of brain-boosting ought to be taken with a pinch of salt for now. “Unless the studies have been done, one can assume they’re not going to have any effect on mental health,” he says. Still, he’s optimistic about the future. “The field right now is evolving very strongly and quickly. There’s a lot of important research to be done. It’s still early days.”
Probiotics has become one of the biggest “bug” words among nutrition and health professionals today, partly because of all the time the scientific community has devoted to researching the topic. Research has shown that probiotics are effective in reducing and treating various ailments ranging from antibiotic-induced diarrhea, Clostridium difficile and other digestive disorders. Partly due to all the science and media buzz, manufacturers have been introducing (and marketing) probiotic products left and right. NPR news recently featured a report on all the potential benefits that probiotics can do ranging from curing colicky babies to and prevention of heart disease. Although more research is needed, this is encouraging evidence on the many benefits that probiotics can offer.
In the past couple of years, there were reports suggesting the use of probiotics offering immune health benefits. The article from Environmental Nutrition offers more insight into this.
Boost Your Immunity with Probiotics
Environmental Nutrition: February 2014 Issue
Inside each one of us is an “inner ecosystem”—a unique microbiome teeming with bacteria that lines the gastrointestinal (GI) tract or gut, which is the largest organ of immunity in the body. Fortifying the gut microflora with probiotics—also known as friendly bacteria—should be one of your top health priorities, as this promotes a stronger immune system. “We know that the make-up of our gut microbiome—the total of all microorganisms in the gut—has changed over time, due to environmental factors, and that this change may be partially responsible for the rise in prevalence of allergic and autoimmune disorders, which involve the immune system,” explains registered dietitian nutritionist Rachel Begun, MS, RDN.
Plant foods, such as whole grains and fruit, and yogurt with live and active cultures boost gut bacteria.
Boost plant foods. A plant-based, high-fiber diet is the best way to positively impact your gut microflora, according to an August 2013 article in the Journal of the Academy of Nutrition and Dietetics. Fiber-rich plants boost a greater volume and diversity of microorganisms in the gut, offering better defense against disease-causing invaders. And researchers are discovering that just by eating fewer calories, you can change your gut bacteria profile for the better.
“It’s best to eat whole foods that are natural sources of probiotics, as these are nutrient-dense foods that contribute other health benefits, such as yogurt made with live and active cultures, fermented vegetables like kimchi and sauerkraut, fermented soybean products like miso and tempeh, as well as kombucha, fermented tea,” says Begun.
Prebiotics (non digestible carbs that act as food for probiotics)
“It’s just as important to eat a diet rich in prebiotics, which are the foods that fuel the good bacteria in the gut.” Prebiotic foods include high-fiber plants, such as artichokes, asparagus, bananas, raisins, onions, garlic, leeks, and oats.
Scientists at the Buck Institute for Research on Aging have promoted health and increased lifespan in Drosophila by altering the symbiotic, or commensal, relationship between bacteria and the absorptive cells lining the intestine. The research, appearing in the January 16, 2014 edition of Cell, provides a model for studying many of the dysfunctions that are characteristic of the aging gut and gives credence to the growing supposition that having the right balance of gut bacteria may be key to enjoying a long healthy life.
Even though recent research in humans has linked the composition of gut flora with diet and health in the elderly and the list of age-related diseases associated with changes in gut bacteria include cancer, diabetes, and inflammatory bowel disease, lead author and Buck faculty Heinrich Jasper, PhD, says there is no systematic understanding of how we go from having a young, healthy gut to one that is old and decrepit. “Our study explores age-related changes in the gut that include increased oxidative stress, inflammation, impaired efficiency of the immune response, and the over-proliferation of stem cells,” said Jasper. “It puts these changes into a hierarchical, causal relationship and highlights the points where we can intervene to rescue the negative results of microbial imbalance.”
Who would have thought that the human body contains over 10 times the amount of bacterial cells as human cells? These bacteria — now collectively called the gut microbiota — number in their trillions and are made up of more than a 1,000 different species most of which are beneficial in some way.
“Research is starting to show that the food we eat has a huge bearing on the composition of this collective and also that the profile of the collection of bacteria can be associated with a person’s health status,” explains Dr Paul Ross, Head of the Teagasc Food Research Programme and Principal Investigator at the Alimentary Pharmabiotic Centre, Teagasc, Food Research Centre, Moorepark.
To the team at the Alimentary Pharmabiotic Centre (APC), an SFI-funded CSET at Teagasc, Food Research Centre, Moorepark and at University College Cork, the study of the human microbiota has the potential to transform much of the thinking around basic human nutrition, gut health and disease prevention: “This has been made possible through developments made in DNA sequencing technology which has allowed the study of complex microbial communities such as the human gut microbiota, the majority of which cannot be cultured on an individual basis,” explains Dr Ross.
Although the composition of the microbiota is highly stable during adulthood, there are times when it can be highly dynamic — such as at the extremes of life, e.g., following birth, during inflammatory bowel conditions, gastrointestinal infection and in the elderly. Despite this stability, the microbiota also displays a high degree of interindividual variation reflecting differences in lifestyle, diet, host genetics, etc.
In a project called ELDERMET, a team of UCC/Teagasc scientists headed by Professor Paul O’Toole has recently profiled the faecal microbiota from elderly people in different residences including community, day-hospital, rehabilitation or long-term residential care locations.
This study found that the microbiota correlated with the residence location. “The results demonstrated that the individual microbiota of people in long-stay care was significantly less diverse than those that resided in the community,” explains Dr Ross. “In addition, these subjects were also clustered by diet by the same residence location and microbiota groupings. Interestingly, the separation of microbiota composition correlated significantly with health parameters in these individuals including measures of frailty, co-morbidity, nutritional status, markers of inflammation and with metabolites in faecal water.”
Taken together these data suggest that diet can programme the gut microbiota — the composition of which correlates with health status. Such a suggestion opens up great potential for the food industry in the design of food ingredients and supplements which may in the future shape the microbiota in a particular direction to correlate with an improved consumer health status. Interestingly, a related study called INFANTMET, funded by the Department of Agriculture, Food and the Marine and led by Professor Catherine Stanton at Teagasc Moorepark, is looking at the development of the gut microbiota in early life as a consequence of breast feeding.
All people have trillions of bacteria living in their intestines. If you place them on a scale, they weigh around 1.5 kg. Previously, a major part of these ‘blind passengers’ were unknown, as they are difficult or impossible to grow in laboratories. But over the past five years, an EU-funded research team, MetaHIT, coordinated by Professor S. Dusko Ehrlich at the INRA Research Centre of Jouy-en-Josas, France and with experts from Europe and China have used advanced DNA analysis and bioinformatics methods to map human intestinal bacteria.
-The genetic analysis of intestinal bacteria from 292 Danes shows that about a quarter of us have up to 40% less gut bacteria genes and correspondingly fewer bacteria than average. Not only has this quarter fewer intestinal bacteria, but they also have reduced bacterial diversity and they harbour more bacteria causing a low-grade inflammation of the body. This is a representative study sample, and the study results can therefore be generalised to people in the Western world, says Oluf Pedersen, Professor and Scientific Director at the Faculty of Health and Medical Sciences, University of Copenhagen.
Oluf Pedersen and Professor Torben Hansen have headed the Danish part of the MetaHIT project, and the findings are reported in the highly recognised scientific journal Nature.
The gut is like a rainforest
Oluf Pedersen compares the human gut and its bacteria with a tropical rainforest. He explains that we need as much diversity as possible, and – as is the case with the natural tropical rainforests – decreasing diversity is a cause for concern. It appears that the richer and more diverse the composition of our intestinal bacteria, the stronger our health. The bacteria produce vital vitamins, mature and strengthen our immune system and communicate with the many nerve cells and hormone-producing cells in the intestinal system. And, not least, the bacteria produce a wealth of bioactive substances which penetrate into the bloodstream and affect our biology in countless ways.
-Our study shows that people having few and less diverse intestinal bacteria are more obese than the rest. They have a preponderance of bacteria which exhibit the potential to cause mild inflammation in the digestive tract and in the entire body, which is reflected in blood samples that reveal a state of chronic inflammation, which we know from other studies to affect metabolism and increase the risk of type 2 diabetes and cardiovascular diseases, says Oluf Pedersen.
-And we also see that if you belong to the group with less intestinal bacteria and have already developed obesity, you will also gain more weight over a number of years. We don’t know what came first, the chicken or the egg, but one thing is certain: it is a vicious circle that poses a health threat, says the researcher.
Take care of your intestinal bacteria
The researchers thus still cannot explain why some people have fewer intestinal bacteria, but the researchers are focusing their attention at dietary components, genetic variation in the human host, exposure to antimicrobial agents during early childhood and the chemistry we encounter daily in the form of preservatives and disinfectants.
A French research team reports a study in the same issue of Nature showing that by maintaining a low-fat diet for just six weeks, a group of overweight individuals with fewer and less diverse intestinal bacteria may, to some extent, increase the growth of intestinal bacteria, both in terms of actual numbers and diversity.
-This indicates that you can repair some of the damage to your gut bacteria simply by changing your dietary habits. Our intestinal bacteria are actually to be considered an organ just like our heart and brain, and the presence of health-promoting bacteria must therefore be cared for in the best way possible. Over the next years, we will be gathering more knowledge of how best to do this,” says Oluf Pedersen, whose research team is studying, among other things, the impact of dietary gluten on gut bacteria composition and gut function.
Towards innovative early diagnostics and treatment options
Obesity and type 2 diabetes are not just a result of unfortunate combinations of intestinal bacteria or lack of health-promoting intestinal bacteria, Oluf Pedersen emphasises. There are likely many causal factors at play. But the MetaHit researchers’ contribution opens a new universe in which we begin to understand how gut bacteria in direct contact with the surrounding environment have a decisive impact on our health and risk of disease.
-At present we cannot do anything about our own DNA, individual variation in which also plays a crucial role in susceptibility for lifestyle diseases. But thanks to the new gut microbiota research, we now can start exploring interactions between host genetics and the gut bacteria- related environment which we may be able to change. That is why it is so exciting for us scientist within this research field– the possibilities are huge, says Oluf Pedersen.
-The long-term dream is to map and characterize any naturally occurring gut bacteria that produce appetite-inhibiting bioactive substances and in this way learn to exploit the body’s own medicine to prevent the obesity epidemic and type 2 diabetes, says Oluf Pedersen.
A study of young twins in Malawi, in sub-Saharan Africa, finds that bacteria living in the intestine are an underlying cause of a form of severe acute childhood malnutrition.
The research, led by Washington University School of Medicine in St. Louis and reported Feb. 1 in the journal Science, shows how dysfunctional communities of gut microbes conspire with a poor diet to trigger malnutrition.
Childhood malnutrition is a common problem in Malawi, and while a poor diet clearly plays a critical role, it is not the only factor. Scientists have long puzzled over why some children are afflicted by the condition but not others, even those in the same household who eat the same foods. This has led to the realization that a lack of food alone cannot explain its causes.
The standard treatment is a peanut-based, nutrient-rich therapeutic food, which has helped to reduce deaths from the condition. But the new study shows that the therapeutic food only has a transient effect on the gut microbes. Once the therapeutic food is discontinued, the community of microbes in the intestine and their genes revert to an immature state, in the children and in the mice.
This may explain why many malnourished children gain weight when they are treated with therapeutic food but remain at high risk for stunted growth, neurological problems and even malnutrition and death after treatment is stopped, the researchers say…
While the food seemed to kick start maturation of the gut microbiomes of the severely malnourished children, its benefits were only temporary. Four weeks after the therapeutic food was discontinued, the gut microbiomes of the malnourished children either failed to progress or even regressed, while those of the healthy co-twins continued to mature on a normal trajectory…
“There is much more work to do,” Gordon says. “It may be that earlier or longer treatment with existing or next-generation therapeutic foods will enhance our ability to repair or prevent the problems associated with malnutrition.
“We are also exploring whether it is possible to supplement the therapeutic food with beneficial gut bacteria from healthy children, as a treatment to repair the gut microbiome,” he explains. “We hope that these studies will provide a new way of understanding how the gut microbiome and food interact to affect the health and recovery of malnourished children.”
The billions of bugs in our guts have a newfound role: regulating the immune system and related autoimmune diseases such as rheumatoid arthritis, according to researchers at Mayo Clinic and the University of Illinois at Urbana-Champaign.
Larger-than-normal populations of specific gut bacteria may trigger the development of diseases like rheumatoid arthritis and possibly fuel disease progression in people genetically predisposed to this crippling and confounding condition, say the researchers, who are participating in the Mayo Illinois Alliance for Technology Based Healthcare.
The study is published in the April 2012 issue of PLoS ONE.
“A lot of people suspected that gut flora played a role in rheumatoid arthritis, but no one had been able to prove it because they couldn’t say which came first — the bacteria or the genes,” says senior author Veena Taneja, Ph.D., a Mayo Clinic immunologist. “Using genomic sequencing technologies, we have been able to show the gut microbiome may be used as a biomarker for predisposition.”…
…Researchers found that hormones and changes related to aging may further modulate the gut immune system and exacerbate inflammatory conditions in genetically susceptible individuals…
“The gut is the largest immune organ in the body,” says co-author Bryan White, Ph.D., director of the University of Illinois’ Microbiome Program in the Division of Biomedical Sciences and a member of the Institute for Genomic Biology. “Because it’s presented with multiple insults daily through the introduction of new bacteria, food sources and foreign antigens, the gut is continually teasing out what’s good and bad.”
The gut has several ways to do this, including the mucosal barrier that prevents organisms — even commensal or “good” bacteria — from crossing the lumen of the gut into the human body. However, when commensal bacteria breach this barrier, they can trigger autoimmune responses. The body recognizes them as out of place, and in some way this triggers the body to attack itself, he says….
More research needed, still these scientists may be on to a contributing factor in weight control…
Microorganisms in the human gastrointestinal tract form an intricate, living fabric made up of some 500 to 1000 distinct bacterial species, (in addition to other microbes). Recently, researchers have begun to untangle the subtle role these diverse life forms play in maintaining health and regulating weight….
Research conducted by the authors and others has demonstrated that hydrogen-consuming methanogens appear in greater abundance in obese as opposed to normal weight individuals. Further, the Firmicutes — a form of acetogen — also seem to be linked with obesity. Following fermentation, SCFAs persist in the colon. Greater concentration of SCFAs, especially propionate, were observed in fecal samples from obese as opposed to normal weight children. (SCFAs also behave as signaling molecules, triggering the expression of leptin, which acts as an appetite suppressor.)
While it now seems clear that certain microbial populations help the body process otherwise indigestible carbohydrates and proteins, leading to greater energy extraction and associated weight gain, experimental results have shown some inconsistency. For example, while a number of studies have indicated a greater prevalence of Bacteroidetes in lean individuals and have linked the prevalence of Firmicutes with obesity, the authors stress that many questions remain.
Alterations in gut microbiota are also of crucial concern for the one billion people worldwide who suffer from undernutrition. Illnesses resulting from undernutrition contribute to over half of the global fatalities in children under age 5. Those who do survive undernutrition often experience a range of serious, long-term mental and physical effects. The role of gut microbial diversity among the undernourished has yet to receive the kind of concentrated research effort applied to obesity — a disease which has reached epidemic proportions in the developed world.
Exploiting microbes affecting energy extraction may prove a useful tool for non-surgically addressing obesity as well as treating undernutrition, though more research is needed for a full understanding of regulatory mechanisms governing the delicate interplay between intestinal microbes and their human hosts….
Exciting new data presented at the International Liver Congress™ 2012 shows the gut microbiota’s causal role in the development of diabetes and non-alcoholic fatty liver disease (NAFLD), independent of obesity.(1) Though an early stage animal model, the French study highlights the possibility of preventing diabetes and NAFLD with gut microbiota transplantation – the engrafting of new microbiota, usually through administering faecal material from a healthy donor into the colon of a diseased recipient.(2) …
…”This study shows that different microbiota cause different metabolic responses in animals. By implanting microbiota from healthy mice, the study authors prevented the development of liver inflammation and insulin resistance, both indications of liver disease and diabetes. Thus, gut microbiota transplants could have a therapeutic role in the development of these diseases.”
The RR mice also showed lower levels of microorganisms than usually found in the healthy gut. Lachnospiraceae was identified as the species most important in developing fatty liver and insulin resistance.
At present, the intestinal microbiota is considered to constitute a “microbial organ”: one that has pivotal roles in the body’s metabolism as well as immune function. Therefore transplantation aims to restore gut functionality and re-establish a certain state of intestinal flora.
…In another animal microbiome experiment, Jeffrey Gordon, a biologist at Washington University in St Louis, took a suite of microbesfrom the guts of both obese and lean mice and transplanted them into the guts of microbe-free mice. The mice that received the microbiomes of the obese mice gained significantly more weight than did the mice with the lean-mouse microbiomes. The results were the same regardless of whether the obesity of the donor mice was due to genetics or diet. Although caloric intake is still the most important factor in obesity, Gordon’s research suggests that the microbiome may play a significant role by affecting the ability to extract energy from food and to deposit that energy as fat:
Researchers hope to achieve similarly dramatic results in humans next. A critical step in making this happen is deciphering how microbes communicate. “The establishment of healthy microbial communities almost certainly requires chemical messaging between the species present in the human host,” says Texas A&M University biochemist Paul Straight, who studies interactions among bacteria. Microbes can use chemical signals, including small molecules, proteins, and DNA, to encourage neighboring organisms to grow or to tell them to stop growing. If researchers can capture and understand these molecular exchanges, they might be able to produce a kind of phrase book of chemical reactions. Such information could then be used to initiate this kind of molecular conversation on command, with an eye toward promoting the growth of helpful microbes or stunting harmful ones.
Specially packaged mixtures of microbes, known as probiotics, may also prove useful for balancing microbes in the gut (See “Bugs for Breakfast,” opposite), Probiotics are now generally sold as health food supplements, and many of them are promoted as magic bullets that can improve metabolism or bolster immunity. Since they are as yet unregulated by the FDA, though, it is impossible for the consumer to know exactly what is inside; labels on over-the-counter products can be deceptive. Scientists who have tested them have often found something quite different from what the product promises. Nevertheless, carefully regulated probiotics, which introduce nonpathogenic competitors to disease, could be effective at balancing the gut microbiome…..
Excerpt from the 12 January 2012 news article
New research published online in the FASEB Journal suggests that the types and levels of bacteria in the intestines may be used to predict a person’s likelihood of having a heart attack, and that manipulating these organisms may help reduce heart attack risk. This discovery may lead to new diagnostic tests and therapies that physicians use to prevent and treat heart attacks. In addition, this research suggests that probiotics may be able to protect the heart in patients undergoing heart surgery and angioplasty….
High diversity and a variety of bacteria in the gut protect children against allergies as opposed to some individual bacterial genera. These are the findings of a comprehensive study of intestinal microflora (gut flora) in allergic and healthy children, which was conducted at Linköping University in Sweden.
One hypothesis is that our immune system encounters too few bacteria during childhood, which explains the increasing proportion of allergic children. However it has been difficult to substantiate the hypothesis scientifically.
“We conducted the study in collaboration with Karolinska Institute and the KTH Royal Institute of Technology which substantiates the so-called hygiene hypothesis. Children acquire intestinal microflora from their environment, and in our society they are probably exposed to insufficient bacteria that are necessary for the immune system to mature”, says Thomas Abrahamsson, paediatric physician and a researcher at Linköping University….
It is the composition of intestinal microflora during the first weeks of life that show signs of being critical to the immune system’s development. In the absence of sufficient stimuli from many different bacteria, the system may overreact against harmless antigens in the environment, such as foods. The risk of developing asthma at school age for children afflicted by these allergies is five to six times higher.
Premature Babies Harbor Fewer, but More Dangerous Microbe Types (ScienceDaily (Dec. 8, 2011)
“One of the most comprehensive studies to date of the microbes that are found in extremely low-birthweight infants found that hard-to-treat Candida fungus is often present, as well as some harmful bacteria and parasites
Researchers at the Duke University Medical Center and Nicholas School of the Environment looked at the microbes in 11 premature infants and found much less diversity than in full-term infants.
“The babies’ guts were taken over by microbes we know are dangerous if they get into the blood,” said senior author Patrick Seed, MD, PhD, assistant professor of pediatrics at Duke. “Even after the babies were no longer on antibiotics, healthier bacteria didn’t appear in the babies very quickly. This may be one reason why premature babies are so vulnerable to infections.”……