Effects of Early Introduction of Allergenic Foods Followed by Ad-libitum Consumption, on Food Allergic Sensitisation, Allergy and Measures of Child Health at 8 Years of Age in Exclusively Breastfed Infants

Sensitisation/Allergy:

Food allergy (FA) is common, increasing in prevalence and represents a public health concern in many countries. FA increasingly affects geographic regions where rates of FA were previously low.(1-5) Data from the Enquiring About Tolerance (EAT) study, which enrolled 1303 exclusively breastfed three month old babies from the general population, showed that 8% of children had proven immediate-onset FA at three years of age. This equates to almost 1 in 10 children. (1) The early-introduction of specific food allergen(s) to infant diets is a successful strategy for the prevention of FA. Introduction of peanut to the infant diet before 11 months of age, protected against the development of peanut allergy in a high-risk, atopic population.(6) This effect persisted despite cessation of peanut consumption for 12 months.(7) In the EAT Study, children from the general population were randomised either to consume six commonly allergenic foods (cow's milk, egg, peanut, wheat, fish and sesame) from four months of age (early introduction group (EIG)), or to follow Department of Health (DoH) advice to exclusively breastfeed until about 6 months of age (standard introduction group (SIG)). The per-protocol analysis revealed a reduction in any FA of 7.3% versus 2.4% (p=0.01), for peanut allergy of 2.5% versus 0% (p=0.003) and for egg allergy 5.5% versus 1.4% (p=0.009) in the SIG and EIG respectively. (8) In the EAT study, between 1 and 3 years an intention-to-treat analysis (ITT) of sensitisation to individual foods showed a significant cumulative treatment effect of 35% (p=0.0095) in the EIG (unpublished data). Furthermore, in the per-protocol analyses (PP), we showed a statistically significant reduction of 41.6% (p=0.01) in skin prick test (SPT) sensitivity to any food at 1 year, and again at 3 years with a 67.3% relative reduction (RR) (p=0.002) in the EIG. These findings were particularly significant for individual food; at 3 years there was a relative reduction in skin-prick sensitivity to all individual foods and particularly for peanut (RR 67.1% p=0.007).

FA is a dynamic condition with egg and milk allergy typically developing in infancy and being outgrown and peanut and sesame allergy usually developing between the ages of 3-6 and persisting into adulthood. Whilst early introduction of commonly allergenic foods is effective in preventing food allergy in early childhood and within the confines of a randomised controlled trial (RCT), the longevity of this novel approach has not been tested and little is known about whether these effects are sustained after 'real world' ad libitum consumption. The EAT-On Study aims to investigate this by following-up children who were previously enrolled in the EAT Study when they are 8 years of age and investigating the natural history of food allergy, and how the intervention that was applied when children were 4-6 months of age influences food allergic sensitisation and clinical food allergy when they are 8 years of age.

Child Health:

Whilst the UK Department of Health recommends exclusive breastfeeding (EBF) until around six months of age, surveys suggest this is achieved by only 1% of mothers(9). Given the lack of EBF till 6 months of age, the majority of infants will require additional nutrition provided from formula and/or solid weaning foods. Indeed, 75% of infants have been introduced to solid food by 5 months of age (9). The nutritional consequences of different weaning regimens may have important consequences on obesity outcomes, but rigorous trials in this area are difficult to undertake, not least because of the necessary ethical concerns that pertain to the comparison of breast-feeding with alternate or complementary feeding strategies. The EAT cohort presents a unique opportunity to study this question further as the diet consumed by children who participated in the EIG of the EAT study is much higher in protein than breastmilk alone. Good quality studies have found that consumption of high protein formula milk in early infancy increases the risk of overweight in later childhood compared with breastfeeding, but the effect of high protein solid food consumption alongside breastfeeding in early infancy has not been studied. The majority of infants have solid food introduced before 6 months of age, and updated guidance advocates the introduction of a high protein food (peanut) from 'around 6 months of age' (UK(10) and Australia(11)), or at 4 months of age (USA(12)) to prevent a new onset of peanut allergy. It is therefore timely to explore how early diet, particularly with respect to high protein weaning diet, influences childhood obesity. This will lead to the development of clearer guidance in respect to early weaning diet which extends to other high protein foods, while taking in to account the risk of childhood obesity.