I’ll get right to the point… probiotics do not consistently perform well against allergic diseases such as asthma, eczema, rhinoconjunctivitis (itchy eyes) and allergic rhinitis (i.e., stuffy nose, runny nose, sneezing and post-nasal drip). Don’t get me wrong, there are clinical studies in the literature that make claims of efficacy and I list a few in the tables below. But when experts consider all of the data as a whole, there’s simply not enough evidence to support their use against allergies.
If you’ve read my previous blogs, you’ll know that my position on probiotics is that 1) they are safe and can be used as supplements to a healthy diet and lifestyle in order to support healthy digestion and immunity and 2) they are useful to address occasional bouts of infectious diarrhea, upper respiratory tract infections, constipation, some IBS symptoms and several other conditions. My positions are based on sound scientific and clinical evidence and as a consumer of probiotics, I want to be certain that I am taking probiotics for the right reasons.
A Closer Look at Probiotics and Allergies:
Allergic diseases such as eczema, asthma and rhinoconjuctivitis are non-infectious inflammatory conditions in which individuals become sensitized and produce antibodies in response to ordinary exposures to pollen and other allergens. The incidence of these diseases has increased significantly in the last 50 years and some scientists hypothesize that the increase is due to reduced exposure to microorganisms early in life, resulting in an imbalanced immune response.
Studies have demonstrated that individuals with allergies have low gut microbiota diversity compared to non-allergic individuals. Therefore, some scientists have hypothesized that it may be possible to alter the microbiota using probiotics to alleviate allergy symptoms. Since the efficacy of probiotics for the treatment of allergic disease is a controversial subject, it’s important to consider what clinical studies say about their use.
A meta-analysis of 17 clinical trials that included 4,755 children in which probiotic supplement was provided during pregnancy and early infancy showed that supplementation lowered the incidence of eczema but did not help in treating asthma, wheezing or rhinoconjunctivitis. However, a separate meta-analysis of 12 randomized controlled trials that included 781 children showed that there was no significant benefit when using probiotics to treat eczema.
These studies show that current probiotic supplements do not prevent or reduce asthma and rhinoconjunctivitis and may or may not help prevent eczema. However, there is still debate regarding the use of probiotic supplementation during pregnancy and infancy for the prevention of eczema. Meanwhile, it is important that scientists continue to investigate this area to more fully understand the role of gut microbiota in allergic diseases and to identify probiotic therapies that may be useful.
The table below lists some of the probiotic strains that have been tested in clinical trials for the prevention of allergic disease in infants and children. In some cases, these strains did not show any benefit and so it’s important to click on the references below if you are interested in learning more about the results.
|Probiotics for Allergic Diseases in Infants and Children|
|Probiotic Species||References||Dose Per Day||Duration||Strains||Effect|
|Lactoacillus rhamnosus||1, 2, 3, 4, 5||5-20 billion||1-3 months||Lcr35, GG, LC705, 19070-2||Mixed|
|Lactobacillus reuteri||5||20 billion||6 weeks||DSM 122460||Yes|
|Bifidobacterium lactis||3||20 billion||12 weeks||NA||Mixed|
|Bifidobacterium breve||4||400 million||4 weeks||Bbi 99||Mixed|
|Lactobacillus fermentum||6||4 billion||8 weeks||VR1-003PCC||Yes|
|Propionibacterium JS||4||4 billion||4 weeks||JS||Mixed|
A systematic review and meta-analysis of 23 studies with 1,919 adult patients with allergic rhinitis (i.e., stuffy nose, runny nose, sneezing and post-nasal drip), treated with various probiotic preparations, demonstrated that probiotic supplementation was beneficial in 17 of the studies, whereas 6 trials showed no benefit. The authors of the review conclude that probiotics may benefit patients suffering from allergic rhinitis but that many more studies are required to offer a firm recommendation. The jury is still out on whether probiotics are beneficial for the alleviation of allergic rhinitis in adults. In the meantime, if you’d like to dig into the specific strains and clinical study outcomes, I have provided the table below. Go to the Reference section for links to the specific studies, results and conclusions.
|Probiotics for Allergic Diseases in Adults|
|Probiotic Strain||References||Dose Per Day||Duration||Strains||Effect|
|Lactobacillus rhamnosus||7||5 billion||5.5 months||ATCC 53105||No|
|Lactobacillus casei shirota||8||40 billion||2 months||LcS||No|
|Bifidobacterium longum||9||50 billion||3.5 months||BB536||Yes|
|Bifidobacterium longum||10||50 billion||3 months||BB536||Yes|
|Bifidobacterium longum||11||50 billion||1 month||BB537||Yes|
|Lactobacillus acidophilus||12||30 billion||2 months||L-92||Yes|
|Lactobacillus paracasei||13||40 - 90 billion||2 months||ST11||Yes|
|Lactobacillus plantarum||14||870 million||1.5 months||No. 14||Yes|
It’s clear that the human gut microbiota plays a role in allergies. Whether dysbiosis (i.e., the imbalance of gut microbes that results in a loss of diversity) plays a causative role in allergies or is a consequence, remains to be determined. While probiotics have been shown time and again to be effective in boosting our immune systems to fight certain infections, the existing clinical evidence for the use of probiotics to treat allergies is weak.
Ultimately however, our response to probiotics is unique and personal. One individual may report relief from allergic symptoms while another may report no relief using the same probiotic preparation. Identifying therapies that target dysbiosis on a personal level may, ultimately, lead to improved treatment or prevention of allergies.
About the Author:
Douglas Toal, Ph.D is a medical microbiologist with extensive knowledge and expertise in clinical and environmental microbiology with additional training in biochemistry, metabolism and anti-aging medicine. Dr. Toal is founder of Liberty Bion, Inc. You can connect with Dr. Toal on his blog or on Twitter @DrDougToal.
Douglas Toal, PhD is a medical microbiologist with extensive knowledge and expertise in clinical and environmental microbiology with additional training in biochemistry, metabolism and anti-aging medicine. He is board-certified in Medical & Public Health Microbiology and has performed extensive research in the cell-to-cell signaling strategies that bacteria use to communicate. His current interests include validating innovative diagnostic methods for the identification of clinical disease. He frequently blogs about the application of probiotics in human health, recent discoveries in gut microbiota function and trends in anti-aging medicine and wellness.