Probiotics in Allergic Disease: Are We There Yet?

Atopic dermatitis is a chronic, relapsing, inflammatory skin condition commonly seen in infants & children. Characterized by redness, scaling, oozing or crusting lesions, it usually presents in a typical morphological manner. It generally begins in early childhood and could be the initial step in the “atopic march”.¹

The prevalence of AD is estimated to be 15-20% in children and 1-3% in adults, and the incidence has increased by 2- to 3-fold during the past decades in industrialized countries.¹ Evidence obtained from more recent articles shows that AD is a universal problem affecting infants, children, young adults, and adults. In studies done worldwide, the highest prevalence was among Swedish children at 34% and the lowest was among Tunisian children at 0.65%. These numbers have made it a global public health concern.²

Ongoing research has established evidence that the development of atopic dermatitis is associated with the skin as well as the gut microbiome. This originates from the concept that bacterial diversity & composition are correlated to the onset and development of different non-communicable diseases including allergic disease.

Evidence shows changes in the gut microbiota in patients with atopic dermatitis (AD). The gut microbiome of patients with AD possessed less diversity with significantly reduced beneficial microbes (Lactobacillus, Bifidobacterium) and higher counts of E. coli, C. difficile & S. aureus compared to healthy individuals. This prompted researchers to believe that infants with less gut microbial diversity seemed to have increased susceptibility to AD.³

Taking this into context, compelling evidence advocates for probiotic consumption as a significant and effective alternative to supplying beneficial bacteria and restoring gut dysbiosis.

Probiotics is defined by the FAO/WHO as “live microorganisms, which when used in adequate amounts, confer a health benefit on the host”.⁴

It is guaranteed to promote the synthesis of nutrients (amino acids & vitamins) in the host and increase the content of short-chain fatty acids in the gut lumen which in turn, lower the intestinal pH and inhibit the growth of pathogens. It contributes to the improvement of gut microbial composition, influences the immune responses thereby, decreasing the clinical symptoms of AD.³

Probiotics supplementation with strains such as Lactobacillus GG and Saccharomyces boulardii prompt the release of cytokines and increase production of IgA in the gut. Probiotics have also regulated and decreased the expression of pro-allergic cytokines (IL-5 and IL-13).³

B. animalis subspecies lactis Bb12 and B. longum Bb46 have significantly inhibited the growth of the harmful bacteria in the intestine, S. aureus and E. coli, both associated with the development of atopic eczema.⁵

Over the past few decades, there has been increased research in the role of probiotics to treat and/or prevent allergic disease.

A recently published EAACI position paper on food allergy prevention states that there is “no recommendation for or against probiotics for pregnant &/or breastfeeding women &/or infants alone or in combination with other approaches to prevent food allergy in infants and young children.” Their systematic review included nine trials. While there is no evidence that the use of probiotics caused any harm, the clinical effects could not be extrapolated to other probiotics.⁶

In another review, results for both treatment and prevention of AD were inconsistent. Some probiotic strains affected the proportion of the individual bacterial taxa, while others did not. These were attributed to differences in the dose, probiotic strain used, the duration of administration and the method of analysis.⁷

In view of this, we are reminded that allergic disease and the development of the gut microbiota of infants are complex and multifaceted. Factors to consider include mode of birth delivery, type of feeding, age of administration which would significantly determine the effects of supplementation in this specific population.^3,7

SUMMARY

Atopic dermatitis is a chronic, relapsing, inflammatory skin condition which greatly affects infants and children. Inceptive research has suggested that gut dysbiosis may be a contributing factor with probiotics being recognized as an additional form of treatment or prevention because of how it influences the immune response.

While data has been both promising and supportive, no consensus exists to recommend the use of probiotics in the treatment or prevention of atopic eczema.  More sizeable, well-controlled clinical studies are needed to reinforce this finding.

“A better understanding of diet–microbiome–host interactions is needed, but represents an enormous opportunity to refine dietary interventions with the goal of supporting a healthy microbiome and human well-being.”⁷

REFERENCES

1 Nutten S: Atopic Dermatitis: Global Epidemiology and Risk Factors. Ann Nutr Metab 2015;66(suppl 1):8-16.

2 Hadi HA, Tarmizi AI, Khalid KA, Gajdács M, Aslam A, Jamshed S. The Epidemiology and Global Burden of Atopic Dermatitis: A Narrative Review. Life (Basel). 2021 Sep 9;11(9):936.

3 Fang Z, Li L, Zhang H, Zhao J, Lu W, Chen W. Gut Microbiota, Probiotics, and Their Interactions in Prevention and Treatment of Atopic Dermatitis: A Review. Front Immunol. 2021 Jul 14;12:720393.

4 Food and Agriculture Organization of the United Nations. Health and nutritional properties of probiotics in food including powder milk with live lactic acid bacteria. http://www.who.int/foodsafety/publications/fs_management/en/probiotics.pdf (Accessed on 27 May, 2022).

5 Martinez FA, Balciunas EM, Converti A, Cotter PD, de Souza Oliveira RP. Bacteriocin Production by Bifidobacterium Spp. A Review. Biotechnol Adv (2013) 31(4):482–8. doi: 10.1016/j.biotechadv.2013.01.010.

6 Halken S, Muraro A, de Silva D, Khaleva E, Angier E, Arasi S, Arshad H, Bahnson HT, Beyer K, Boyle R, du Toit G, Ebisawa M, Eigenmann P, Grimshaw K, Hoest A, Jones C, Lack G, Nadeau K, O'Mahony L, Szajewska H, Venter C, Verhasselt V, Wong GWK, Roberts G; European Academy of Allergy and Clinical Immunology Food Allergy and Anaphylaxis Guidelines Group. EAACI guideline: Preventing the development of food allergy in infants and young children (2020 update). Pediatr Allergy Immunol. 2021 Jul;32(5):843-858.

7 Davis EC, Dinsmoor AM, Wang M, Donovan SM. Microbiome Composition in Pediatric Populations from Birth to Adolescence: Impact of Diet and Prebiotic and Probiotic Interventions. Dig Dis Sci. 2020 Mar;65(3):706-722.