Two studies indicate that oral supplementation with live probiotic bacteria can relieve the symptoms of allergic asthma and the allergic skin condition eczema.
These two separate studies provide more evidence that probiotic bacteria, so called "friendly bacteria", are essential for good health, especially where the immune system is concerned.
Ever since scientists begun the serious study of the micro-organisms that inhabit our intestines a couple of decades ago, the evidence has been stacking up that these bugs are as much a part of a healthy human immune system as our immune cells themselves. It's thought that probiotic bacteria provide benefits to their human host in a number of different ways. They produce chemicals that stimulate our immune systems, and they help guard against infection by less friendly bugs, for example.
Researchers have studied the effects probiotic bacteria have in numerous different ways. They have found that animals who are intentionally kept sterile, so that they have no bacteria at all in their gastrointestinal system, have dysfunctional immune systems. Additionally, children who have a certain composition of intestinal 'flora', fewer friendly bacteria and more not so friendly bacteria to put it simply, tend to develop more allergies. So it seems that having the right balance of micro-organisms in our guts, and particularly the right amounts of certain probiotic bacteria, is an essential part of maintaining a healthy immune system and preventing the development of allergic diseases. This is borne out by numerous studies that have tested specific types of bacteria to see if they can restore the balance of organisms within the gut and also treat the symptoms of allergy. In many many cases, the results have shown that they can.
The two studies recently published add to the evidence for this. In the first of these, researchers from McMaster University and St. Josephs Healthcare in Canada looked at the effects of two different probiotic bacteria on the response to antigen challenge in a mouse model of allergic airway inflammation. In the second study, carried out at the Skin and Allergy Hospital, University of Helsinki, Finland, a preparation of 4 different probiotic bacteria was tested to see if it could reduce the incidence of allergies in children.
The study carried out at McMaster University tested the probiotic bacteria Lactobacillus reuteri and Lactobacillus salivarius, two well known strains. Mice with allergic airway disease were separated into 2 groups, with one being given L. reuteri and the other L. salivarius prior to being given a challenge dose of an antigen to trigger the allergic response.
After the challenge the 3 different measurements were taken from the mice; airway responsiveness to methacholine, influx of inflammatory cells to the lung, and cytokine levels in bronchoalveolar lavage fluid. Methacholine is a chemical commonly used to assess bronchial hyperresponsiveness and diagnose asthma. An influx of inflammatory cells and cytokines (chemicals produced by immune cells) indicates an allergic response is underway.
The results from this study showed that the probiotic bacteria L. reuteri, but not L. salivarius was effective at reducing all of the indicators of allergic airway disease/asthma that were tested. The probiotic reduced the influx of inflammatory cells (eosinophils) and reduced levels of a host of cytokines - TNF, MCP-1, IL-5 and IL-13, in the fluid of the lungs. Interestingly the researchers also gave the mice supplements of dead L. reuteri and found that these had no effect. The study indicates that oral supplements os the probiotic bacteria Lactobacillus reuteri could be an effective treatment for allergic asthma.
L. reuteri seems to be one of the most promising probiotic bacteria. Only last week we reported on a study showing this bacteria was effective in the treatment of colic in infants (see story).
In the Finnish study which appears in the Journal of Allergy and Clinical Immunology, both probiotic bacteria and a prebiotic preparation containing galacto-oligosaccharides were used. Prebiotics are specific types of sugar that are known to be easily utilized by probiotic bacteria and thus encourage their growth. In the study 1223 pregnant women whose unborn babies were at high-risk for allergic diseases (due to family history) were split into 2 groups. The researchers gave 461 of the women the 4 probiotic bacteria preparation for 2-4 weeks prior to delivery, and 464 were given a placebo over the same period. After delivery the women's babies were given the same probiotic preparation as well as the prebiotic for the first 6 months of their lives before they gave birth, and then to their babies for the first 6 months of their lives.
The aim of this study was to find out if the supplementation with probiotics and prebiotics reduced the incidence of allergies in the children. This was a double-blind placebo controlled trial, the same type used for pharmaceutical drugs and the kind considered to produce the most reliable results.
When the infants reached 2 years of age the researchers evaluated the cumulative incidence of allergic diseases (food allergy, eczema, asthma, and allergic rhinitis), and IgE sensitization using skin prick test responses or the presence of antigen specific IgE in blood samples. IgE is a type of antibody produced by the immune system that binds with food particles, pollen, and other allergens to cause an allergic reaction. An antigen specific antibody is one which targets a specific allergen such as wheat or a particular grass pollen. The composition of the infants intestinal bacteria was also monitored both during treatment and at the 2 year point.
The results from the study showed that although there was no reduction in the total incidence of allergic disease amongst the infants compared to average, the probiotic supplement did reduce IgE associated allergic diseases and was particularly effective at reducing cases of eczema and allergic eczema. The research also demonstrated that the probiotic bacteria successfully colonized the infants gastrointestinal tracts. The intestines of those infants given the probiotic and prebiotic contained much higher numbers of Lactobacilli and bifidobacteria compared to the infants given the placebo. This point is worth noting as these bacteria are known to offer many other benefits besides those investigated in this study.
The researchers conclude that their results suggest an inverse relationship between atopic diseases (allergies, asthma, eczema) and colonization of the gut by probiotics. They state that the prevention of eczema in high-risk infants is possible by modulating the composition of the infant's gut flora with probiotics and prebiotics.
So here we have 2 more studies to add to the already lengthy list demonstrating the benefits of various probiotic bacteria, and in the case of the second study, prebiotic substances as well, on treating and/or preventing allergic diseases. There is already enough evidence to make ensuring infants have the best chance of developing a health gut flora a high priority in the healthcare system. The research suggests this can be achieved by various methods including supplementing mother's and infant's diets with probiotics and prebiotics, as well as avoiding the unnecessary use of antibiotics which wipe out these beneficial bacteria. In the coming years further research will no doubt provide more information with regard to specific probiotic bacteria and preparations that can be used to prevent and treat specific allergic diseases.
Oral treatment with live probiotics may help alleviate allergic asthmatic response. Am J Respir Crit Care Med, 2007; DOI:10.1164/rccm200606-821OC
Probiotics and prebiotic galacto-oligosaccharides in the prevention of allergic diseases: A randomized, double-blind, placebo-controlled trial.
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