xRead - September 2022

Wise et al.

Page 42

assessed both by direct measurement with a hygrometer and indirectly by observing the presence of mold spots on the walls. • Aggregate Grade of Evidence: C (Level 2b: 3 studies; Level 3b: 10 studies; Table VI.B-4). In summary, the clinical relevance of early inhalant allergen exposure to AR development is still debated. Despite several indepth reviews and a growing body of literature, 561-563 no definitive and consensus may be drawn regarding risk-benefit of early inhalant allergen exposure, and further research is welcomed to address the unmet needs on this issue. In some studies, early sensitization to food allergens has been linked to the development of AR in childhood. 468,564,565 A meta-analyses by Alduraywish et al. 564 demonstrated that food sensitization in the first 2 years of life was associated with an increased risk of AR during childhood (OR = 3.0; 95% CI, 2.1 to 4.2) (Table VI.C). The relationship between sensitization to food allergens and the subsequent development of AR during childhood has been investigated in both population-based and high-risk cohorts. 468,565-568 While there is a statistically significant correlation in the high-risk cohort, 567 there are mixed results in the population-based studies. 566,568,569 These findings prompted prospective investigation of the effects of allergen avoidance in utero and during early childhood. In an RCT evaluating the effects of in utero exposure to food antigens and the development of AR, 162 high-risk pregnant women (history of respiratory allergy to animal danders and/or pollens) were randomized 1 of 2 diets during the last 3 months of pregnancy: either very low ingestion of hen’s egg and cow’s milk, or a daily ingestion of 1 hen’s egg and 1 [liter] of cow’s milk. A total of 163 infants were followed prospectively up to 18 months of age, at which time the incidence of atopic disease, including AR, was evaluated in a blinded fashion. There was no significant difference in the incidence of AR between the 2 groups. 570 In another RCT, restricted diet during pregnancy (cow’s milk-free and egg-free diet from week 28 to delivery) was associated with a small but statistically significant lower mean gestational weight gain and did not protect the offspring from atopy. 571 The pooled results of 2 trials suggest that maternal food antigen avoidance may be associated with a higher risk of preterm birth and a possible adverse effect on mean birth weight without beneficial effects on AR development in the children. 570,571 of 2073 children, delayed introduction of solids (past 4 or 6 months of age) was not associated with decreased odds for AR, asthma, or sensitization against food or inhalant allergens at 6 years of age. In fact, food sensitization occurred more frequently in children who were introduced to solids later. 572 In a prospective RCT of food allergen avoidance in infancy, the incidence of subsequent allergic disease, including AR, was assessed. The intervention arm of the trial required mothers to avoid cow’s milk, egg, and peanut during the last trimester of pregnancy and subsequent lactation, and required infants to avoid cow’s milk until age 1 year (casein hydrolysate supplementation before age 1), egg until age 2 years, and peanut and fish until age 3 years. Compared to maternal-infant control pairs who Studies have also evaluated the early introduction of foods compared to food avoidance with respect to the effects on development of allergic disease. In a prospective birth cohort study

Author Manuscript Author Manuscript Author Manuscript Author Manuscript

VI.C. Food allergens (in utero and early childhood exposure)

Int Forum Allergy Rhinol . Author manuscript; available in PMC 2020 June 10.