Sunday, December 29, 2013

How to Cook For Kids With Food Allergies

The prevalence of food allergies is on the rise. You may have personal experience with food allergies amongst your friends, family, or even your own kids.  I decided to ask my friend David Jeong, M.D. to offer some insight on the topic of food allergies.  Dr. Jeong grew up in Iowa, attended Northwestern University for his undergraduate work, the University of Iowa for medical school, the University of Michigan for his residency in Pediatrics, and the University of Washington for his fellowship training in Allergy/Immunology.  Here is his response to my questions: Thank you Dr. Jeong!

What are some of the common ways food allergies present?

Hives, eczema, diarrhea, nausea/vomiting, abdominal cramping, nasal congestion, watery/red/itchy eyes, cough, and wheezing.

What are some of the more widely accepted theories amongst allergists as to why there has been a dramatic rise in food allergies in recent years?

a) Hygiene hypothesis: lack of early childhood exposure to (allergens)...leads to an imbalanced immune system, skewing its development more toward allergy.
b) Food preparation: roasting vs boiling peanuts, for example. Western countries roast more than boil, which leads to higher cooking temps (180C) and leads to increased stability of heat stable proteins in peanut...leading to greater allergenicity.

c) The Dual Exposure Hypothesis. This has to do with what happens to the immune system when a person is exposed to a food by skin contact vs oral ingestion. Incidental skin contact on household surfaces can be (allergy) promoting, exposure via oral ingestion can promote immune tolerance. Up until 2008, in countries like the US, pediatric and allergy guidelines advised avoidance of high risk foods until between one and three years of life, which left the only likely mode of exposure during those years of life through incidental skin contact. Without the oral exposure to...promote immune tolerance, the incidence of allergies began to rise. As of 2008, both the American Academy of Pediatrics and the American Academy of Allergy Asthma & Immunology revised their guidelines to suggest that delayed introduction of milk, eggs, nuts, and seafood may not be the right thing to do. There has been plenty of literature to support this over the last 5-10 years.

What are the most common food allergies?  Is there a mechanism behind why certain foods are more allergenic than others?

Milk, egg, wheat, soy, nuts, and seafood account for more than 90% of all food allergies in western countries. All of these foods are "allergenic" to equal degrees, particularly early in life. What is different is the natural history of certain foods compared to others. Nuts and seafood allergies persist into adulthood to a greater degree (> or = 80% as opposed to less than 20% with the other foods listed), likely because of the very heat stable proteins within these foods, leading to a persistent immune response with repeated exposures.

Why are some food allergies diminished by cooking (i.e. cooked fruits?)

It has to do with the protein structures within the foods. The classic example is oral allergy syndrome, aka pollen food cross-reactivity syndrome. There are proteins in certain fruits, vegetables, and nuts that share a high degree of cross reactivity to pollens from birch tree or timothy grass, to name a few. When a person is allergic to these pollens and then eats a fresh fruit (ie apple), that person could develop a sensation of itching, tingling and a lump in the throat. When that same person eats an apple pie, no reaction! The baking process essentially denatures or destroys the protein, rendering them unrecognizable to the allergic person.

What is the role of blood tests in identifying food allergy?

We have to distinguish whether a person is "positive" without ever having eaten that food versus being "positive" but eats the food regularly without any symptoms.

If the former and the test is done by blood testing...then it is strongly recommended that the patient consult with an allergist. (Allergists use) certain predictive value cut offs based on the medical literature, and these cut offs show that even if a person has a "positive" result it may not be necessary to avoid that food.

If the latter, keep eating the food!! The test is not perfect, and...antibodies can be picked up by testing that have nothing to do with true clinical reaction.

If there is a strong family history of allergy, what can parents do to prevent food allergies from developing in their children?

Remember, blind avoidance is not necessarily required. In this case, innocent until proven guilty. If a mother is pregnant, it is not recommended that she blindly avoid nuts, seafood, or any other food with the thought that it will prevent her soon to be born child from developing food allergies.

The current evidence (suggests that) exposure to a food early and often seems to be more allergy preventive than delayed and infrequent exposure early in life. (i.e. consider introducing peanut containing foods at age one rather than age three).

The only action that has been shown to provide any benefit is if the mother can breastfeed for at least the first four months of life. This could lessen the chance that this child develops allergies down the road.

What resources do you recommend for parents who have kids with allergies?
The handouts from UpToDate for patients (beyond the basics) provide very accurate information. Just search "UpToDate Food Allergy for patients."

This holiday season, you may be asking yourself, "What should I bring to the holiday party?" Being sensitive to the prevalence of food allergies can ensure that you bring something that everyone can enjoy.  In the following clip, I show you an easy dish that is sure to be a hit at your next holiday party:

Click to Facebook :

Here is a link to the recipe I used in the above clip:
Happy New Year!

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