FEATURE
DON’T GO NUTS:
The Current View of Food Allergies
Wes Sublett, MD
F
ood allergy is an important public
health problem as it affects count-
less children and adults. Food aller-
gies affect up to six to eight percent
of children, and two to three percent
of adults. The incidence of food allergies has
increased significantly over the past 20 years.
In the US, peanut allergy has more than tri-
pled between 1997 and 2008, and food allergy related emergency
visits nearly tripled in a four-year period. Although many foods have
been documented to cause allergic reactions, cow’s milk, hen’s eggs,
peanuts, tree nuts, fish and shellfish are responsible for most serious
allergic reactions. Although most egg and cow’s milk allergies resolve
in early childhood, the development of spontaneous tolerance to
peanut or tree nut allergies occurs in less than 20 percent of patients.
Patients and their families experience significant anxiety related to
fear of accidental exposures leading to allergic reactions. 1-5
Food allergy results in significant direct medical costs for the
US health care system and even larger costs for families facing food
allergy. In a cross-sectional survey of 1,643 US caregivers of a child
with a current food allergy, the overall economic cost was estimated
at $24.8 billion annually ($4,184 per year per child). Direct medical
costs were $4.3 billion annually including clinician visits, emergency
department visits and hospitalizations. Costs borne by the families
totaled $20.5 billion annually, including lost labor productivity,
out-of-pocket and opportunity costs. 6
Food allergy is most often caused by a specific IgE-mediated
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LOUISVILLE MEDICINE
reaction to a food protein with the potential to cause food-in-
duced anaphylaxis, a serious allergic reaction that is rapid in onset
and may cause death. Foods triggers have been identified in other
non-IgE-induced mechanisms, including food protein-induced
enteropathy (FPIES), exacerbations of eosinophilic GI disorders
(EGIDs) (eosinophilic gastritis, eosinophilic enteritis, eosinophilic
colitis, and eosinophilic gastroenteritis), and food-induced allergic
contact dermatitis. For the sake of this article, we will focus on only
IgE mediated food allergy. 5
Medical history is the most critical part of making an accurate
diagnosis of food allergy. Food allergy is typically characterized by
a defined exposure to a food allergen that is followed by a rapid
onset and evolution of multiple symptoms involving multiple organ
systems. If food allergy is suspected, the patient should then be
evaluated by a board-certified allergist to confirm the diagnosis.
At that time, additional diagnostic modalities include skin prick
testing to specific food allergens and specific serum IgE blood test
may be done.
“Routine” panels of food skin prick testing or in-vitro specific
serum IgEs should not be ordered without a historical rationale
and tolerated foods (foods ingested without problems) need not be
tested. False positive prick and in-vitro testing, without a supporting
history, may cause needless anxiety and unnecessary elimination of
foods. Oral food challenges remain the gold standard for diagnosis
of food allergy. However, challenges are time and resource intensive
and carry the risk of an anaphylactic reaction. Neither skin prick
testing nor specific IgE blood test results alone are considered suffi-