Monday, 2 December 2013
Preventing food allergies in Children: How little we know about an emerging public health crisis
Sorry for the gap in posting. It is now December and perhaps the world will begin to turn more slowly. Thanks for your patience.
Perhaps it is a sign of the times, but food allergies were rarely diagnosed in the past and while now likely overdiagnosed, the number of student with peanut, egg and ‘milk’ allergies in school has become a challenge for schools grappling with having emergency procedures in place to manage anaphylaxis and classroom food policies.
In this changing milieu, a statement from the Canadian Pediatric Society is worth reviewing for its excellent review of the topic.
Despite the increased interest in food allergies in children, and in anaphylaxis issues in students, the article provides no definitive conclusions beyond stating that delayed introduction has no benefit. Newer thinking is exploring whether early introduction can actually be preventive. Even the value of breastfeeding is based on weak evidence and becomes questionable which will lead to horrific rebuttals from some biased professionals.
Two current studies in the United Kingdom LEAP and EAT (obviously somewhere somebody has a full time job developing catching acronyms for research studies) hope to provide further information on appropriate interventions.
If there is a consistent message on food allergy prevention, it is “we really don’t know, but perhaps we will know more in the future”. Read the full statement at CPS position on food allergy prevention
Regardless of the lack of evidence, the CPS in conjunction with Canadian Society of Allergy and Clinical Immunology produced a set of recommendations. Note that the only recommendation which has better than Grade 2B evidence is on selection of formula where breastfeeding is not indicated. 2B is considered weak evidence generally of low quality methodologies.
· Do not restrict maternal diet during pregnancy or lactation. There is no evidence that avoiding milk, egg, peanut or other potential allergens during pregnancy helps to prevent allergy, while the risks of maternal undernutrition and potential harm to the infant may be significant. (Evidence II-2B)
· Breastfeed exclusively for the first six months of life. Whether breastfeeding prevents allergy as well as providing optimal infant nutrition and other manifest benefits is not known. The total duration of breastfeeding (at least six months) may be more protective than exclusive breastfeeding for six months. (Evidence II-2B)
· Choose a hydrolyzed cow’s milk-based formula, if necessary. For mothers who cannot or choose not to breastfeed, there is limited evidence that hydrolyzed cow’s milk formula has a preventive effect against atopic dermatitis compared with intact cow’s milk formula. Extensively hydrolyzed casein formula is likely to be more effective than partially hydrolyzed whey formula in preventing atopic dermatitis. Amino acid-based formula has not been studied for allergy prevention, and there is no role for soy formula in allergy prevention. It is unclear whether any infant formula has a protective effect for allergic conditions other than atopic dermatitis. (Evidence IB)
· Do not delay the introduction of any specific solid food beyond six months of age. Later introduction of peanut, fish or egg does not prevent, and may even increase, the risk of developing food allergy. (Evidence II-2B)
· More research is needed on the early introduction of specific foods to prevent allergy. Inducing tolerance by introducing solid foods at four to six months of age is currently under investigation and cannot be recommended at this time. The benefits of this approach need to be confirmed in a rigorous prospective trial. (Evidence II-2B)
· Current research on immunological responses appears to suggest that the regular ingestion of newly introduced foods (eg, several times per week and with a soft mashed consistency to prevent choking) is important to maintain tolerance. However, routine skin or specific IgE blood testing before a first ingestion is discouraged due to the high risk of potentially confusing false-positive results. (Evidence II-2B)