Published Online: January 2, 2016
The rise in food allergy in developed countries is an intriguing phenomenon that has captured the attention of both the medical research community and the media. Although we need to be circumspect about the extent to which it has risen and which countries are most affected, there is little doubt that IgE mediated food allergy and anaphylaxis were rarely reported 50 years ago but are now commonly described. The drivers for this modern day epidemic are poorly understood and indeed it is not clear whether this phenomenon is part of a 2nd wave epidemic of allergy following on from the general rise in allergic disease that was noted around the world at the end of the 21st century or whether the food allergy epidemic is due to a new set of unique factors.
This recent increase in both prevalence and public awareness of food allergy means that clinicians and researchers are frequently asked to explain reasons for the increase in food allergy and families are eager to know whether they can take steps to prevent food allergy in their children. In this issue of The Journal of Allergy and Clinical Immunology: In Practice, Allen and Koplin outline leading theories on risk factors for early life food allergy. They summarise the leading hypotheses to explain the increase in food allergy into “the 5 Ds” - Dry skin, Diet, Dogs, Dribble (shared microbial exposure) and Vitamin D.
What can we tell our families?
1. Emerging evidence suggests that optimisation of early life skin barrier function through decrease in drying soaps and detergents and increase in the use of non-allergenic moisturisers is a reasonable clinical recommendation.
2. Current allergy recommendations are that infants should be introduced to solids around the age of 4-6 months irrespective of family history risk and that allergenic solids do not need to be avoided by infants when solids are introduced or by mothers when breastfeeding or lactating.
3. It is universally agreed that breastfeeding should be the first and most important source of nutrition for the infant as it contains a vast array of bioactive factors including hormones, growth factors, neuropeptides, anti-inflammatory and immunomodulatory agents that influence many physiological systems, and promote normal gut colonization. Its role in protection against food allergy risk remains unclear.
4. Data is conflicting as to whether modified formula is protective against allergic disease. In particular there is insufficient evidence that modified formula is protective against food allergy and some guidelines are being revised to reflect this.
5. There is insufficient data that probiotics or prebiotics protect against food allergy.
6. At this point in time there is insufficient evidence to support the use of Vitamin D either as a prevention or treatment for food allergy.
Findings from observational cohorts and the first large-scale intervention trials for food allergy prevention support early oral allergen exposure to reduce the prevalence of specific food allergies, which is informing changes in public health guidelines at the population level. Further research will be required to assess the impact of these guideline changes on the population prevalence of food allergy.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.