Science is studying how bacteria impact allergies
The rates and severities of allergies have risen very quickly over the last twenty years and are much more prevalent in the industrialized world than they are elsewhere. Some estimates have stated as many as one in five Americans has some sort of allergic condition.
The current prevailing scientific theory is that changes to the mix of bacteria in the gut are at the root of many allergic disorders. There is a lot of study being done to see if probiotics are the key to treating or preventing allergic diseases.
What is the Cause of the Rate of Increased Allergies?
Hygiene Hypothesis
The current, developed world is a much more sterile place than it used to be. The American Academy of Allergy, Asthma and Immunology believes that the most credible theory behind why allergy rates are rising so quickly in industrialized countries is the “Hygiene Hypothesis.” Our immune systems have evolved as long as humans have existed to be constantly vigilant – looking out for harmful attackers and responding quickly to the threat they pose to our health. The Hygiene Hypothesis theory says that in our current “too clean” environment where our immune systems are no longer exposed to as many actual disease-causing pathogens as our bodies have evolved to handle, our bodies are now identifying substances that are not actually harmful, but are merely irritants (such as dust, mold or certain foods), as attackers. The immune system then raises an immune response to these irritants / allergens when exposed to them, which is what we call an allergic reaction.
Children exposed to a range of microbes are less likely to have allergies than those who haven’t been exposed to as many. Studies show that children raised on a farm are less likely to develop allergies, asthma and eczema than those who have not spent time there. Children who have older siblings, have a pet or attend day care are less likely to develop allergies as they age than those who do not. What farms, older siblings, daycares and pets have in common is that they are teeming with microbes (bacteria, viruses, organisms in the soil). This supports the hygiene hypothesis that early exposure to a range of microbes can prevent later allergic disease.
Unlike the recent past, people now are more likely to live in urban or suburban environments. Children don’t spend as much time outside playing in the dirt (and being exposed the microbes that live in it) as they used to, and those do get quickly and thoroughly scrubbed down afterwards. It’s difficult to find a liquid hand soap that isn’t anti-bacterial. Antibiotics are prescribed quickly and often to fight the first sign of illness. Many childhood diseases have been greatly reduced or eradicated. Foodborne illnesses have been greatly reduced due to regulated food service sanitation requirements. The Hygiene Hypothesis states that in a sanitized environment there are not as many real health threats to fight against, hence the normal development of young children’s immune systems is interrupted, and as they age their immune systems are more likely to react abnormally to allergens (normally harmless substances that trigger an abnormal immune reaction in some people) – creating an allergic reaction.
Although it is a good thing for public health that exposure to dangerous disease-causing pathogens has been reduced, the dramatic increase in allergies and allergic diseases (asthma and eczema) may be the unintended consequences of our more sanitized environment.
Antibiotics
Epidemiological Surveys have shown the rise in use of antibiotics has corresponded to the increased rates of allergies and asthma over the last forty years. We know that antibiotic use causes long-term change to the mix of bacteria living in the gut. Researchers have hypothesized that the change of gut microbes triggered by antibiotics is somehow responsible for the development of certain allergies.
Medical researchers, led by Dr. Gary Huffnagle at the University of Michigan, have shown that following a course of antibiotics, which altered the mix of microbes in their digestive tracts, mouse lungs react differently when allergens are introduced to them as compared to the control group who did not receive antibiotics. When we breathe in particles, due to the human anatomy, we are also swallowing (and digesting) some of particles found in the air. The hypothesis that the scientists were testing was that the normal, healthy microbes that live in the gut somehow communicate with and train the immune system not to overreact to ordinary, harmless allergens. But when the normal gut microbes are altered by antibiotics, the changed microbiome might not have the same calming effect on the immune system. In their 2004 study, the mice that had been treated with antibiotics showed in increase in hypersensitivity and reactivity to harmless yeast spores when inhaled into the lungs as compared to the mice that hadn’t been treated with antibiotics and did not have an allergic reaction. scientists from the University of Michigan Medical School will present results of experiments with laboratory mice indicating that antibiotic-induced changes in microbes in the gastrointestinal tract can affect how the immune system responds to common allergens in the lungs.scientists from the University of Michigan Medical School will present results of experiments with laboratory mice indicating that antibiotic-induced changes in microbes in the gastrointestinal tract can affect how the immune system responds to common allergens in the lungs.
Preventing Allergic Reactions
It has been proposed that one way to slow down the rising tide of allergy related illness is to expose the human immune system to harmless bacteria, particularly when a child is very young and the immune system still evolving. Having a diversity of gut microbes is healthier than having fewer species of microbes.
Children with pets in the household when born are statistically less likely to go on to develop allergies and asthma than those living in a pet-free home.
Studies have shown that newborns who later develop either asthma or allergies commonly have a different composition of microbes in their guts within the first few months of life than do those who remain unaffected by these disorders.
A 2013 study found that babies born by C-Section were five times more likely than those who were not to develop allergies during the first two years of life. They have also been shown to be more likely to develop asthma and food allergies.
Probiotics for Babies Born by Cesarean Section
It has been observed that infants who develop allergies have a different mix of gut bacteria than those who do not. Infants who are delivered by C-section also have been shown to have a different mix of gut microbes than those delivered in a vaginal birth.
Many healthy microbes are transferred from mother to child during the passage through the birth canal and go on to colonize the infant’s digestive tract and become a critical component of the baby’s developing immune system.
However, if a mother’s vaginal bacteria are unhealthy, those too will be passed along to the infant during birth. Therefore, it is important for women planning on having a vaginal birth to promote the health of their gut bacteria by avoiding unnecessary antibiotics, avoiding affecting the vaginal Ph by douching, and eating prebiotic and probiotic containing foods.
Babies delivered via C-section do not get the same bacterial exposure from their mothers and because of this, have guts containing a different mix of bacteria than babies delivered via the birth canal. This is important because the mix of gut bacteria can increase the child’s later risk of allergies.
In a 2009 study published in the online Journal of Allergy and Clinical Immunology, researchers studied 1,200 pregnant women whose babies were at risk of developing allergies. One group of expectant mothers received a daily dose of a mix of probiotics while the control group received a placebo. Once born, the infants of the probiotic group were given a supplement of the same daily mix of probiotics, along with a prebiotic to provide food for the probiotics, until six months of age. The control group of babies got a placebo for the same period. All babies were followed up with until age five.
For the babies delivered in vaginal births, there was no difference in the rate of allergies they later developed between the treated and the control groups. For babies born by C-section, however, those given the probiotic had a lower rate of allergic disease.
Bacterial Bath for Babies Born by Cesarean Section
Recent research efforts at alleviating potential harmful effects to a baby’s immune system triggered by C. section birth have focused on exposing infants to microbes harvested from their mother’s vagina. Gauze is soaked within the birth canal and then rubbed thoroughly over the infant’s face and skin. Although this seems dramatic and perhaps even unsanitary, it should be remembered that had the baby been born vaginally, there would have been no way to prevent these same microbes from completely covering the infant and getting into its nose, ears and mouth. Results show that infants who had been swabbed with their mother’s microbes had gut microbiomes more similar to their vaginally delivered peers.
Further study will reveal whether this beautifully simple, low-tech intervention can yield great benefits for C. section delivered infants throughout their lives.
Eczema
Eczema is a disease where the skin becomes inflamed or irritated and is usually itchy, too. It affects about 10% of infants and 3% of adults in America. It’s related to allergies because the children of parents with allergies are much more likely to have children with eczema and children with eczema are more likely to grow up and develop allergies and asthma. People with eczema often have flare-ups of their condition when exposed to allergens.
Research has shown that probiotics can be useful in preventing eczema when taken by pregnant women.
Researchers at the Norwegian University of Science and Technology performed a randomized, double-blind study where they gave milk containing probiotics to pregnant women planning to breastfeed their babies, starting at 36 weeks of pregnancy through three months after they gave birth. The researchers followed their infants from birth until two years of age. The milk contained Lactobacillus acidophilus, Bifidobacterium lactis, and Lactobacillus rhamnosus GG. The researchers chose not to give probiotics to the babies themselves because of lack of data over the safety of giving probiotics directly to babies. In this study, the probiotics somehow seemed to affect their mother’s breast milk in a way that provided a benefit to the children. The rates of eczema in the babies of the probiotic treated mothers was reduced 40% from the control group. They also found that for those children in the probiotic group who did develop eczema, their disease was less severe, on average, than cases that developed in the control group.
The fact that a probiotic supplement given to a pregnant and nursing mother can potentially prevent eczema or reduce its severity, should it develop, is terrific news. So far, L. rhamnosus is the bacteria that has shown the most benefit for this purpose.
Later research done to see if the same benefits could be seen preventing asthma in babies by administering probiotics to their mothers did not have the same positive results. Unfortunately, there was no reduction in the rate of asthma in babies born from mothers who were given probiotics.
Recent research has revealed a link between having eczema and the development of food allergies in infants. If it is a causal link, preventing eczema in children, perhaps through administration of probiotics to the mother during pregnancy and to the infant later on, could have the additional benefit of preventing food allergies as well.
Probiotics for Treatment of Allergies
Seasonal Allergies
Hay fever is an allergic reaction to pollen or fungal spores. Often seasonal allergies are triggered by plants coming into bloom. Grass allergies are common.
The conventional wisdom from the natural medicine crowd holds that probiotics can be helpful in treating seasonal allergies or hay fever. There are many probiotic products on the market aimed at these allergy sufferers. There is some data to back up these claims.
Medical researchers have tested whether a daily probiotic supplement of Lactobacillus casei in milk for six months could affect the immune response (and thus potentially reduce allergic symptoms), when allergy sufferers were exposed to grass pollen.
Blood tests taken during the peak grass pollen season revealed a much more balanced immune response in the probiotic group than in the control group. Frustratingly, researchers in this study did not evaluate whether allergy symptoms themselves were affected by the probiotics.
In a small 2009 study on 47 children with confirmed allergies to birch tree pollen, the subjects were treated with probiotics (Lactobacillus acidophilus and Bifidobacterium lactis) for 4 months prior to the onset of birch season. The control group receive a placebo. The results showed that treated patients had a significant reduction for nasal eosinophilia, – which is the white blood count in the nasal tissue. The reduced white blood cell count means a likely improvement in the allergy sufferers discomfort due to complaints of a stuffy and runny nose.
This study was quite limited in that it only tested one allergen (grass pollen) and one probiotic bacteria. Symptom reduction was not examined. There is a lot more study that can be undertaken in this area.
If you have tried treating seasonal allergies with probiotics, either successful or not, please let us know about experience, either positive or negative in the comments below.
Eczema and Atopic Dermatitis
Because probiotics have been shown to be helpful in preventing eczema in babies, and because probiotics are helpful in reducing inflammation, it seems natural that they would also be beneficial in treating this uncomfortable skin condition.
Atopic dermatitis is a sub-type of eczema and probiotics have shown some benefit in treating it. There have been several studies that looked at treating atopic dermatitis with probiotics. A 2011 randomized placebo-controlled trial found that a 1 week supplementation of Lactobacillus salivarius significantly improved skin symptoms and blood markers of allergic response in adults. A 2012 study found that L. salivarius supplementation, particulary when provided to the subjects along with a prebiotic (food for the probiotic bacteria), was helpful in controlling atopic dermatitis symptoms in children.
Unfortunately, however, limited research that has been done to date has not shown much benefit to treating eczema in infants with probiotics.
Notwithstanding the lack of overwhelming scientific support, many eczema patients believe that probiotics improve the skin disease and there are many probiotic supplements that are developed and marketed at eczema suffers. Treating eczema is a commonly touted reason for drinking kefir, a fermented milk beverage containing high doses of a wide range of beneficial microbes and there have been lots of reports of its improving the disease.
Please let us know in the comments if you have tried treating eczema with probiotics. If you have found them helpful, let us know what bacteria you took.
Food Allergies
This is a significant and growing problem in the industrialized world. In the US, 5% of pediatric patients and 4% of adult patients have a document food allergy. Certain food allergies can be lethal. Preventing exposure to foods that a child is allergic to can be a fulltime, stressful job that can decrease the quality of life for both the patient and her family. Even taking even taking every possible precaution, exposure can still happen due to mislabeling or other mishaps, with potentially fatal results. The restricted diet that is necessary may lead to nutritional deficiencies.
The hygiene hypothesis is often blamed for this increase in food allergies. Food allergies also seem to run in families. Because the infants are exposed to fewer bacteria in our hyper-clean modern environment, their immune system may start to recognize otherwise harmless food allergens (such eggs, milk, shellfish or peanuts, for example) as potentially deadly pathogens requiring a massive immune response. It is the immune response itself that makes the food allergy so scary. The body causes the airways to swell and the response can trigger an asthma attack or even shock.
In studies, certain bacteria, Clostridia, have been shown to reduce or even prevent sensitization to food allergens, such as peanuts. The sterile mice showed higher reactivity to food allergens than their normal peers. However, when the Clostridia were reintroduced in to their microbiomes, food allergies were reduced.
It is exciting to think that altering the microbial mix in the human gut could be a future way to prevent or treat deadly food allergies.
Lactose Intolerance
Lactose intolerance is technically not an allergy. It is an intolerance to the lactose found in dairy foods. People with this condition lack the enzyme in the small intestine that would normally break down lactose so it can be absorbed by the body. Instead, the lactose enters the large intestine, where bacteria break it down for energy. This causes gas which leads to the uncomfortable symptoms that are the hallmark of lactose intolerance.
There have been some studies that show that probiotics can ease the symptoms of lactose intolerance be enabling the body to digest milk products more easily. Lactobacillus acidophilus has been shown to be helpful. Other studies have found conflicting results.
L. acidophilus, which is found in yoghurt, is a well-studied probiotic that is generally quite safe. If you are otherwise healthy, but suffer from lactose intolerance, it could be worthwhile to try it in supplement or yoghurt form and see if it helps.
Anecdotally, many kefir drinkers have claimed that it has cured their lactose intolerance permanently.
If you are an allergy sufferer, stay tuned to this area of medical research. There is a lot of inquiry being done in the area of gut bacteria and allergy.
