Is there an association between microbial exposure and food allergy? A systematic review

Abstract

The environmental factors driving the recent increase in the prevalence of food allergy (FA) are unclear. Since associations have been demonstrated between microbial exposure and the likelihood of eczema and respiratory allergies, we reviewed the evidence for FA. Medline was systematically searched from inception to the end of July 2012 for studies investigating links between FA and environmental exposures, likely to influence microbial exposure, such as Caesarean delivery, family size, day-care attendance, childhood infections, immunizations and antibiotic use. We selected studies reporting food challenge data, reported doctor-diagnosed (RDD) FA and food sensitization. Methodological differences and study heterogeneity precluded meta-analysis. A total of 46 studies were identified, of which 28 (60.9%) were prospective and 13 (28.3%) used food challenges to diagnose FA. Caesarean delivery was investigated in 13 studies, of which three infant cohorts demonstrated an increase in challenge-proven FA (one cohort) and food sensitization (two cohorts), and one cross-sectional study reported increased RDDFA. Four studies investigated the effect of having siblings, with one infant cohort demonstrating less challenge-proven FA and a cross-sectional study showing a decrease in RDDFA. Attending childcare before 6 months was associated with less challenge-proven FA in one cohort. A cross-sectional survey identified an inverse relationship between hepatitis A serology and peanut sensitization. One of eleven trials investigating probiotics demonstrated a quicker acquisition of milk tolerance amongst allergic infants. Factors influencing microbial exposure may be partly responsible for rising FA burden, but further prospective studies using double-blind placebo controlled food challenges as an outcome are required.

Hygiene factors associated with childhood food allergy and asthma

“…Children who were cared for in a child care center had a decreased prevalence of food allergy in our sample, which has been indicated previously. 20 This inverse association supported the possibility that greater exposure to a diverse array of bacteria in early life can protect the child against atopic disease later in life. 3 Indeed, the microbiome may play a role in maintaining inflammatory homeostasis and immune regulation, 21 including in food allergy.…”

Estudio Transversal: Factores de Riesgo para Alergia Alimentaria en Adolescentes de Cuenca y Santa Isabel, Ecuador

“…Categórica 0= 2 o más hermanos mayores 1= Uno o ningún hermano mayor 1) Revisión sistemática: insuficiente evidencia de asociación por diferencias entre los métodos diagnósticos entre estudios [32]. NE: I 2) Estudio de casos y controles: asociación protectora de los hermanos mayores para el desarrollo de AA [25].…”

“…Categórica 0= No 1= Si 1) Revisión sistemática: cuidados externos antes de los 6 meses se asoció con una menor probabilidad de AA [32]. NE: I 2) Estudio de cohorte: La asistencia a guarderías incrementa la AA [38,39].…”

Introduction of Complementary Foods and Food Allergies: New Studies and Modern Clinical Guidelines

“…Существует «гигиеническая» гипотеза, согласно которой вероятность развития аллергии уменьшается при естественных родах (физиологическая контаминация микрофлорой). Положи-тельную превентивную роль, по некоторым данным, могут оказать наличие в доме животных и даже очередность рождения (младшие дети имеют более высокую нагруз-ку болезнетворными микроорганизмами по сравнению со старшими, что может способствовать формированию противоинфекционного иммунитета и снижать вероят-ность развития аллергии) [11][12][13][14][15]. Гипотеза о профилак-тической роли витамина D предполагает, что снижение обеспеченности им организма ребенка повышает риск развития у него пищевой аллергии [16,17].…”