Lesson 3: Atopic Disease: Allergy, Eczema, Asthma
3.1 Overview
Atopic diseases such as eczema, asthma and food allergy are common in childhood and their prevalence has increased dramatically in both the developed and developing world (Pawankar et al. 2011). The time of exclusive breastfeeding and introduction of complementary foods may influence the development of allergy (Sansotta et al. 2012).
Figure 5: World map of the incidence and lifetime prevalence of atopic eczema symptoms (1990-2010).
Overview of absolute changes in the incidence of atopic eczema and lifetime prevalence of atopic eczema symptoms between 1990 and 2010
Source: Deckers et al. 2012, reprinted from PLOS under Open-Access Licence (Creative Commons Attribution Licence)
Previously, different recommendations have been given on the optimal age of introduction of potentially allergenic foods to infants. However, recommendations agree that
"there is no convincing evidence that avoidance or delayed introduction of potentially allergenic foods, reduces allergies either in infants considered to be at risk for development of allergy or even in those not considered to be at increased risk”.
(Agostoni et al. 2008; Greer et al. 2008; Australasian Society of Clinical Immunology and Allergy (ASCIA) 2010)
A discussion paper has suggest that "tolerance to food allergens appears to be driven by regular, early exposure to these proteins during a 'critical early window' of development” (Prescott et al. 2008). Although this paper discusses that the exact timing of this window is unclear, it has been suggested to be between 4-6 months, and delaying introduction of complementary foods beyond this time may increase the risk of allergy (Prescott et al. 2008).