Guidelines on the Management of Atopic Dermatitis ... - Dermatology

Food allergy in atopic dermatitis:
Sensitisation to foods (presence of raised ImmunoCAP or positive skin-prick tests (SPT)) is
common in atopic dermatitis, but is not synonymous with clinically relevant food allergy.
About 60% of patients with moderate to severe atopic dermatitis are sensitised to food
allergens, 3,4,5,6,7 which is much greater than the overall prevalence of food sensitisation in the
general population of around 16%. 8,9 In 2009, South African infants with atopic dermatitis
were shown to have frequent sensitisation to foods, most commonly egg white (47.1%),
cow‟s milk (28.4%) and peanuts (26.8%). 10 In 2011, infants attending a tertiary dermatology
clinic for atopic dermatitis were shown to have even higher sensitisation rates (66% to at
least one food), most commonly to egg (52%), peanuts (39%) and cow‟s milk (25%). 11
Approximately 30-40% of children with moderate to severe atopic dermatitis seen at
specialised units have co-existing food allergy, 3,4,5,6,12,13,14,15,16,17 but this is less common in
unselected populations and in adults. In 50% of these patients the reaction is an immediate
hypersensitivity reaction coexisting with atopic dermatitis. These immediate concomitant
food allergy reactions usually have non-eczematous cutaneous features 4 with or without
gastrointestinal reactions, respiratory symptoms or anaphylaxis and occur within two hours
of food ingestion. South African data in children attending a tertiary dermatology clinic for
atopic dermatitis (selected and severe cases) show 41% of patients have a concomitant
immediate type food allergy. 11 There is no data on delayed reactions in the South African
setting. International literature on food reactions in children with moderate to severe disease
shows isolated eczematous reactions occur in 10% of reactions (3-4% of such children) and
are usually delayed >6 hours after food ingestion. 1,13,14,17 A combination of non-eczematous
and eczematous reactions occurs in 40% of cases (12-16% of such children). 1,13,14
The same food allergens that cause reactions in the general population are responsible for
the majority of reactions in children with atopic dermatitis. Egg, milk, peanut, wheat and soy
cause 90% of food reactions in children with AD. 18,19
There is no specific diet for the treatment of unselected patients with atopic dermatitis so
patients should not routinely be placed on exclusion diets. 21 Elimination diets are potentially
harmful. 24 Food allergy should only be considered in specific cases, and elimination diets
reserved for those children who have been proven to be allergic and tailored to the individual
after appropriate investigations, including challenge tests where necessary, have been
performed to assess possible food triggers. They must be done under the supervision of a
dietician and should always be combined with atopic skincare. Food allergy is more common
in those with a very early onset of atopic dermatitis, 22 where atopic dermatitis is more
severe 12 and where GIT symptoms are prominent.