By Henry Ehrlich
Probiotics, those dietary supplements that purport to restore to our guts what antibiotics and Caesarian section have taken away, are a big topic on social media. People are constantly talking about the ones they use and/or asking for recommendations from others as if their utility were firmly established, and it is just a matter of finding the right one to restore gut integrity and a healthy immune system. If it were only as easy as Jamie Lee Curtis makes it look on Activia commercials.
Thus I welcomed the publication in the Journal of Immunotoxicology of “Probiotics and diseases of altered IgE regulation: a short review” by two authors, Tamar A. Smith-Norowitz, PhD of the department of pediatrics at SUNY-Downstate School of Medicine, which is just a short walk from my home. Always glad to acknowledge the work of a neighbor. The other author is Martin H. Bluth, of Wayne State University in Detroit.
The authors report “Recent evidence suggests that probiotics can have possible therapeutic benefit in atopic disease states such as allergy, asthma, AD, eczema and related disease states.” Furthermore, “the World Allergy Organization (WAO) guideline panel has recommended using probiotics in (a) pregnant women at high risk for having an allergic child, (b) women who breastfeed infants at high risk of developing allergy and (c) infants at high risk of developing allergy.” However, these recommendations are conditional and supported by low quality of evidence. This is a review of peer-reviewed articles about “probiotics and their clinical effect on diseases of altered IgE regulation including AR (allergic rhinitis), AD (atopic dermatitis), asthma and food sensitization.” The authors say, “there exists little data to support the theoretical nature of probiotic use in humans to alleviate allergic disease.”
Specific probiotics have measurable effects on the activity of the helper cells associated with innate immunity (Th1), which protects us against infections by secreting IgG, and acquired immunity (Th2), which, when it goes haywire resulting in too much IgE, makes us allergic. “In vitro and in vivo studies have shown that probiotic bacteria also have immune-stimulating effects. It has been suggested that microbial stimuli might play a role in the maturation of adaptive T-cell immunity.”
However, direct benefits are hard to prove. The record varies by allergic condition, but in general efficacy is described in those equivocal terms that make journal articles so annoying. “[one study] showed that ingestion of fermented milk containing Lactobacillus paracasi 33 (LP 33) for 30 days could effectively and safely improve the quality-of-life of patients with AR (allergic rhinitis) and perhaps serve as an alternative treatment for AR. In agreement [another study] also demonstrated that ingestion of live LP 33 might improve the quality-of-life for patients with perennial AR induced by house-dust mite. However, another study showed that long-term consumption of fermented milk containing Lactobacillus casei might improve the health status of children with AR, but had no effect on those that were asthmatic.”
For atopic dermatitis and eczema “certain types of nutrient supplementation may be beneficial in improving AD. However, the biological signaling pathways and mechanisms that are triggered by the probiotics in the treatment of AD require further investigation. Thus, the results show that probiotics may reduce severity of AD in infants, but further studies in adults are warranted.”
With food allergies, the authors inhabit the middle ground between “no news” and “awaiting further study”. They write, “Regarding food allergy and sensitization, the use of probiotics, prebiotics, hydrolyzed formula and bacterial lysates in infancy had no effect on food sensitization, but did reduce the incidence of AD (Lau, 2013). Studies by Lau demonstrated that using Bifidobacterium breve and Streptococcus thermophiles in cow milk formula resulted in a slight reduction of food sensitization at 12 months-of-age. However, the study needed further investigation and the success was restricted to certain populations.”
And so on. Reading an article like this, you can certainly understand the temptation in the popular press to overstate and misrepresent results, which resulted in January headlines and sub-heads like this in The Daily Telegraph (UK): “Fatal Peanut Allergies Could be Cured by Probiotics, say Australian Doctors About 80 per cent of children with peanut allergies were able to tolerate peanuts after being treated with large doses of the probiotic Lactobacillus rhamnosus”. It wasn’t until the second paragraph that readers learned, oh yes, by the way, the probiotic was accompanied by oral immunotherapy (OIT). The principal author of that study, Dr. Mimi Tang, is also well represented in Dr. Smith’s review piece. I suspect that the Telegraph’s editors would just like to believe that all this peanut allergy stuff can be dealt with by something you can get at the health food store, when the rest of us know the contrary is true. Dr. Tang is fully aware that her study was a first step and that the next project will involve an additional control group. (The first study had just probiotic plus OIT and a placebo; they need to study OIT-only as well.)
Do probiotics have a place in the allergy discussion? I’m sure they do. I have heard from mothers that certain distinguished investigators recommend certain products. Mount Sinai food allergy researchers are looking into probiotics. We have covered the role of the gut microbiome on this website, and the idea that food allergies are a digestive phenomenon as well as an immune phenomenon. It therefore makes sense that treating one would help with the other. Dr. Martin Blaser wrote in his book The Missing Microbes that commercial probiotics probably can’t hurt (assuming they are what they say they are, but that’s another discussion). However, a few strains out of the thousands that have disappeared from our guts may not be the right ones. As Dr. Smith-Norowitz and her co-author make clear, the evidence, while sometimes suggestive of benefits, is lacking and much more study is needed.
Thanks for the reality check.