With the exception of breastfeeding advice and delay of allergenic foods, pediatricians and dietitians of BC generally agree in their advice and adhere to the 2008 AAP guidelines.
We expected pediatricians would recommend breastfeeding as often as dietitians to prevent atopic dermatitis, but pediatricians recommended it less often (statistically significant). The 2008 AAP statement states that infants at high risk of allergy who are exclusively breastfed [10, 11] for at least 4 months have a decreased incidence of atopic dermatitis ; these infants also have decreased incidence of cow's milk allergy in the first 2 years of life . Infants breastfed for at least 3 months are protected against wheezing in early life [11, 14]. However, a longitudinal study suggested that breastfeeding may actually increase the risk of atopy and asthma later in life . We speculate that pediatricians responded the way they did because many recommend breastfeeding for the other benefits of breast milk, rather than to specifically prevent atopic dermatitis and wheezing. It would have been useful to collect qualitative feedback to understand the rationale for their response.
We also found a difference in the recommendations given by pediatricians and dietitians regarding the avoidance of allergenic foods. Reflective of the 2000 AAP guidelines, pediatricians were more likely to recommend delay of specific foods. These results suggest both groups, but especially pediatricians, would benefit from further education on the lack of benefit in delaying specific food proteins for infants beyond 4 to 6 months of age. The initial premise behind food avoidance/delay to prevent allergy was twofold; firstly, to decrease the incidence of a severe reaction in younger children and secondly, to prevent early gut exposure which was thought to cause sensitization and a subsequent increase in allergy. However, newer evidence suggests that early introduction of some allergenic foods may actually decrease the risk of atopic disease by promoting tolerance through regulatory T-cell pathways, minimizing the chance of sensitization via the skin4. Early and regular introduction of cow's milk formula to supplement breastfeeding may prevent cow's milk allergy . Introduction of cooked egg at 4 to 6 months of age might protect against egg allergy . Early and frequent ingestion of high doses of peanut protein during infancy might induce tolerance and thereby prevent the development of peanut allergy [18, 19]. The UK LEAP study looking at early versus delayed peanut protein introduction in 640 high risk infants with the outcome of peanut allergy at age five years is currently in progress .
In keeping with the lack of consensus in the literature, most dietitians and pediatricians advised mothers that there was no need to abstain from eating peanuts during pregnancy and breastfeeding to prevent the development of peanut allergy. We found that female pediatricians and pediatricians in practice less than ten years were more likely to recommend against peanut abstinence. Studies on peanut during pregnancy are inconclusive. Recently, a study suggested peanut consumption during pregnancy may increase peanut sensitization at 3 to 15 months of age, but there is a clear difference between peanut sensitization (positive allergy skin or blood test to peanut) and true clinical peanut allergy . Low dose weekly peanut exposure during pregnancy and lactation in a mouse model showed that peanut allergy may be decreased . Another study found that daily peanut consumption during pregnancy could increase risk of childhood wheeze and asthma symptoms .
Over half of practitioners appropriately counselled that no mothers need avoid allergenic foods while nursing but a significant number would recommend avoidance for high risk infants, which suggests there could be potential benefit to more education in this area. The 2008 guidelines cite a lack of evidence that maternal dietary restrictions while nursing play a significant role in prevention of atopic disease in infants [13, 24, 25].
Pediatricians were more likely to recommend a partially hydrolyzed rather than an extensively hydrolyzed formula, while equal numbers of dietitians recommended extensively and partially hydrolyzed formulas for allergy prevention. Some studies suggest that extensively hydrolyzed, partially hydrolyzed and amino acid formulas are equally useful for allergy prevention , while others suggest there is a differential effect [27–29]. A recent review suggested infants without a history of eczema in a first-degree relative will receive protective effect from partially hydrolyzed formula, but those infants who have first-degree relatives with eczema should receive extensively hydrolyzed formula [29, 30]. The protective effect of hydrolyzed infant formulas on atopic eczema may last until 6 years of age .
Recommendation of cow's milk formula was the third most popular choice with both groups. Katz et al. found that the incidence of IgE-mediated cow's milk allergy may be decreased by introducing cow's milk based formula early and regularly to infants (daily supplementation of breastfeeding with cow's milk formula). Infants exposed to cow's milk formula before 14 days of age were less likely to develop cow's milk allergy. Infants that were not regularly exposed to cow's milk protein until four to six months of age were at the greatest risk for developing cow's milk protein allergy . Extending our study to explore whether pediatricians who choose cow's milk formula recommend daily ingestion (versus not giving advice on frequency) would be intriguing, and may illustrate a new approach to recommendations based on frequency of ingestion. No convincing evidence exists for the use of soy-based infant formula for the purpose of allergy prevention , and we found that only a small number of pediatricians and no dietitians recommended soy formula.
Our study was limited to surveying dietitians and pediatricians. It would be interesting to poll family physicians who provide the bulk of primary care for Canadian children. The study was limited to British Columbia, Canada and it would be interesting to see opinions elsewhere in the world. A potential confounder in this study was the different mode of survey distribution for the two practitioner groups, with the online survey for dietitians and paper survey for pediatricians. Although the wording was identical, we did not anticipate that many pediatricians would answer in a multi-response fashion to the last two questions that were meant to be single response (dietitians only had the option of single response with the online modality).