Pre‐ and probiotics for allergy prevention: time to revisit recommendations?

Abstract

Reduced intensity and diversity of microbial exposure is considered a major factor driving abnormal postnatal immune maturation and increasing allergy prevalence, particularly in more affluent regions. Quantitatively the largest important source of early immune-microbial interaction, the gut microbiota is of particular interest in this context, with variations in composition and diversity in the first months of life associated with subsequent allergy development. Attempting to restore the health consequences of the 'dysbiotic drift' in modern society, interventions modulating gut microbiota for allergy prevention have been evaluated in several randomized placebo controlled trials. In this review, we provide an Accepted ArticleThis article is protected by copyright. All rights reserved.overview of these trials and discuss recommendations from international expert bodies regarding prebiotic, probiotic and synbiotic interventions. Recent guidelines from the World Allergy Organization recommend the use of probiotics for the primary prevention of eczema in pregnant and breastfeeding mothers of infants at high risk for developing allergy and in high risk infants. It is however stressed that these recommendations are conditional, based on very low quality evidence and great heterogeneity between studies, which also impedes specific and practical advice to consumers on the most effective regimens. We discuss how the choice of probiotic strains, timing and duration of administration can critically influence the outcome due to different effects on immune modulation and gut microbiota composition.Furthermore, we propose strategies to potentially improve allergy preventive effects and enable future evidence-based implementation.

Breastfeeding and the gut-brain axis: is there a role for melatonin?

“…The World Allergy Association recently recommend the use of prebiotics in high-risk pregnancies, including when breastfeeding, highlighting the growing appreciation of the role of the gut in infancy to alterations in the immune response that contribute to later allergy susceptibility (48). Such a perspective would also indicate that increasing gut melatonin, to increase gut bacteria swarming (38), may also have utility in the early modulation of allergy risk.…”

Immunomodulatory effects of probiotic supplementation during pregnancy and infancy in allergy prevention studies

“…Host interactions with microbial organisms from the environment [21] and at mucosal sites, such as the gut [50,64,65] have been proposed to be important for correcting the dysbiotic drift caused by modern living. Probiotics have been proposed to have immunomodulatory effects [66] and promote gut microbiota diversity 12 although evidence for this is scarce in allergy prevention studies (as reviewed in [67]). The intestine provides a unique environment for the development of both immunity and tolerance.…”

“…The studies are summarized in [67] Only the LGG bacteria colonized the children at 10 days and at 3 months of age. There were no significant differences in the abundance of the probiotic bacteria between the groups at 1 and 2 years of age, nor for the bacterial classes and genera, alpha and beta diversity [78].…”

“…Effects on both the innate and adaptive immunity have been investigated, see Table I and [67]. In (TNF) and IL-10) at 6 months was found after postnatal L. acidophilus as compared with placebo administration [116].…”

“…Probiotics have been proposed to have a beneficial effect on gut microbiota composition and the probiotic strain may be transiently detected during the supplementation period in most studies (Table 1) [67]. However, gut microbial diversity promoting effects early in life have not been observed generally, Table I.…”