Several observations converge to support the idea that intelligently selected probiotics might be able to have an impact on allergic diseases. It is well-established that many probiotics can affect immune parameters; proper immune system development requires contact with microbes in early infancy; immune-associated diseases (such as allergy, inflammatory bowel diseases and rheumatoid arthritis) are associated with aberrant colonization; and observational studies show that children raised on farms, with pets, with siblings, in day care – all environments expected to increase exposure to microbes – are at reduced risk of developing allergic diseases. Pulled together, these suggest that interventions, such as probiotics, that enhance microbial exposure, might have potential to reduce the burden of allergy.
But as is often the case with science, not all good hypotheses are confirmed. So what is the evidence for probiotic intervention and allergy? Here is where the field stands:
- Some probiotics when administered to pregnant women and/or their newborns appear to reduce the incidence of atopic dermatitis in infancy and early childhood (Pelucchi et al. 2012)
- Follow-up from these studies has not shown any benefit of probiotics to protect against development of asthma or childhood wheeze (Azad, et al. 2013)
- Some studies suggest certain probiotics can be used as treatment of atopic dermatitis (da Costa Baptista, et al. 2013), but results are mixed and probiotics are not recommended for treating eczema (Boyle et al. 2009)
- There is little direct evidence of probiotics preventing or treating food allergy. However, probiotics that are selected to reduce dietary antigen load by degrading and modifying allergy-inducing food molecules, support gut barrier integrity, and alleviate allergic inflammation may prove worth testing in controlled human studies (Nermes et la. 2014)
Rarely does one study fully inform, so it is useful to look at systematic reviews and meta-analyses, which seek to evaluate the totality of evidence for a specific research question (referenced above). But one interesting study conducted in Singapore by Loo et al. (2014) showed no significant differences between children at the age of 5 who consumed probiotics or not in infancy in the development of any asthma, allergic rhinitis, eczema, food allergy and sensitization to inhalant allergens. Since most allergy benefits seem to be associated with atopic dermatitis in infancy, this negative result seems to support the conclusion that current probiotics only provide a narrow benefit.
Another interesting study on the impact of probiotic consumption on allergy endpoints was published by Bertelsen et al. (2014). This was an observational study (not an intervention trial, which compares probiotics to a placebo) conducted in the general population (not only on at-risk infants) in Norway. The study looked at responses to questionnaires on allergy indices in 40,614 children. Results showed a slightly reduced relative risk of atopic eczema at 6 months (adjusted RR, 0.94; 95% CI, 0.89-0.99) and of rhinoconjunctivitis between 18 and 36 months (adjusted RR, 0.87; 95% CI, 0.78-0.98). No association with asthma was observed.
Taken together, these results seem to suggest that probiotics could play an important role in prevention or treatment of allergies of different etiologies. It seems that optimal probiotic strains for these targets remain to be identified. However, with the exception of prevention of atopic dermatitis, to date probiotics do not have a robust impact on the development of or treatment of allergy.
Azad MB, Coneys JG, Kozyrskyj AL, Field CJ, Ramsey CD, Becker AB, Friesen C, Abou-Setta AM, Zarychanski R. Probiotic supplementation during pregnancy or infancy for the prevention of asthma and wheeze: systematic review and meta-analysis. BMJ. 2013;347:f6471
Bertelsen RJ, Brantsæter AL, Magnus MC, Haugen M, Myhre R, Jacobsson B, Longnecker MP, Meltzer HM, London SJ. Probiotic milk consumption in pregnancy and infancy and subsequent childhood allergic diseases. J Allergy Clin Immunol. 2014; 133(1):165-71.
Boyle RJ, Bath-Hextall FJ, Leonardi-Bee J, Murrell DF, Tang ML. Probiotics for the treatment of eczema: a systematic review. Clin Exp Allergy. 2009 39(8):1117-27
da Costa Baptista IP, Accioly E, de Carvalho Padilha P. Effect of the use of probiotics in the treatment of children with atopic dermatitis; a literature review. Nutr Hosp. 2013;28(1):16-26.
Loo EX, Llanora GV, Lu Q, Aw MM, Lee BW, Shek LP. Supplementation with probiotics in the first 6 months of life did not protect against eczema and allergy in at-risk Asian infants: a 5-year follow-up.Int Arch Allergy Immunol. 2014;163(1):25-8.
Nermes M, Salminen S, Isolauri E. Is there a role for probiotics in the prevention or treatment of food allergy? Curr Allergy Asthma Rep. 2013;13(6):622-30.
Pelucchi C, Chatenoud L, Turati F, Galeone C, Moja L, Bach JF, La Vecchia C. Probiotics supplementation during pregnancy or infancy for the prevention of atopic dermatitis: a meta-analysis. Epidemiology. 2012;23(3):402-14.