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All About
Food Allergies
By: Dr Latha Kumar
Food allergy (FA) or food hypersensitivity
is increasing worldwide. The prevalence is highest in preschool
children, but it can occur at any age. It is more common
in the children who have atopic dermatitis and asthma. FA
occurs when an individual, instead of developing tolerance
to a food, becomes sensitised to it. The symptom range and
severity vary from patient to patient.
Symptoms pertaining to skin and the gastrointestinal
tract are common, like urticaria or chhapaki, itching, redness
of skin, swelling of lips, eyelids, tongue, nausea, vomiting,
diarrhoea and abdominal cramps. Respiratory symptoms like
cough wheezing, sneezing, runny nose and blocked nose may
be present. Life threatening reactions like anaphylaxis
can also occur in some.
Anaemia and the failure to thrive is seen
in some types of allergic reactions. Some people with pollen
or latex (rubber) allergy also develop allergy to certain
foods. This is known as the oral allergy syndrome. Occasionally,
a baby may develop allergy to some food (s) eaten by the
mother via the passage through breast milk, but this is
uncommon.
Food allergy is the manifestation of different
kinds of allergic reactions. Therefore, the timing of reaction
can vary - from almost immediately after eating the culprit
food to a few hours or few days later. In a child with atopic
dermatrtis, itching may occur soon after eating egg (immediate
type of allergy - IgE, mediated) and eczema may worsen after
a day or so (delayed allergic reaction).
Allergy can develop to almost any food,
but some foods are more allergenic. These vary from region
to region depending upon the availability of the food item
processing and eating habits. Allergy to sea food (shrimp,
lobster, prawn, crab, mollusks) is seen in coastal areas
and in land-locked areas where seafoods are freely available.
Similarly, allergy to fish is seen in areas where it is
eaten frequently. Animal milk (cow, buffalo), egg and wheat
are common food allergens. Dals (Mash, arhar, channa and
rajmah, have been reported to cause allergy in some patients
in India. Peanuts and tree nuts (almond, walnut, etc) are
also allergenic to some. Fruits and some food additives
may produce symptoms. Allergy can develop to foods which
were tolerated earlier. Reactions to nuts and seafood tend
to be more severe. Fortunately, milk and egg allergies disappear
with age in most children but
other allergies persist. If FA persists if it occurs late
in life.
Management consists of avoiding the allergenic
food. It is easy to avoid a food which is eaten sporadically,
but excluding a staple food like milk for a young child
or wheat is a major challenge. Moreover, milk, eggs wheat
and soya are used in preparing a number of food items. Those
allergic to such foods must know about all food preparations
likely to contain one or more of these. If a severe reaction
to food occurs, the person concerned must be rushed to the
nearest medical centre. People with severe FA should consult
allergy immunologists to learn how they can reduce the risk
to their life in the case of accidental ingestion of allergenic
foods.
There is evidence to prove that the incidence
of FA and other allergies like atopic dermatitis (infantile
eczema) and asthma can be reduced if babies are exclusively
breast-fed for at least six months. A nursing mother should
avoid allergenic foods in her diet. Common allergenic foods
should be introduced in the child's diet after two years
of age.
The writer, a senior consultant at
Chandigarh's Chaitanya Hospital, was earlier associated
with the PGI.
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