When you react to food
- an allergy or an intolerance?
By Tish Richardson PhD.The saying ‘one man’s meat is another man’s poison’ may be an old
one, but it certainly holds true for an ever-increasing number of
people as they realise they are ‘reacting’ to one or more foods in
their diet. So often this reaction is labelled as a ‘food allergy’
but for most, the body’s reaction is by quite a different pathway
which is described as ‘food intolerance’.
So what do the terms ‘food allergy’ and ‘food intolerance’
actually mean, and why is it necessary to understand the way in which
you react to a food?
Food allergy
With a food allergy, the body’s immune system (its
natural defence system) reacts to a food that is otherwise harmless
to the vast majority of the population. Eating the offending food
(the allergen) sets off a chain of events—the defence system
produces antibodies to a component of the food (typically a protein), and these antibodies
then bind to various cells in different parts of the body which in
turn produce the symptoms seen as the ‘allergic reaction’ . The
nature and extent of this reaction varies on a person-by-person
basis.
For example:
- The food involved. Almost any food has the potential to
cause an allergic reaction in a sensitive person, but certain
foods more commonly provoke a reaction than others. For example,
the most common food allergens in the Australian population are
eggs, fish and shellfish, milk, peanuts, soy, tree nuts (e.g.
almond, brazil, cashew) and wheat, with allergies to sesame
seeds becoming increasingly common.
- The speed of onset of the reaction. The allergic reaction
may occur within minutes of eating the food, in which case it is
called ‘immediate’, or it may occur up to hours later—a
‘delayed’ reaction.
- The severity of the reaction. The allergic reaction to a
food may be mild, such as a few hives, hay fever-like with a
stuffy nose, itching eyes. However, in some people the reaction
can be more severe with symptoms such as swelling around the
mouth (angioedema) or other soft tissues such as the face or
around the eyes, wheezing and difficulty breathing. In rare
cases the reaction can be life threatening involving many
organs of the body simultaneously (anaphylaxis), and require
emergency medical treatment.
- The amount of the food allergen and the type of contact. In
some very sensitive individuals it is not just a matter of
eating a small amount of the food—touching tiny traces left on a
utensil or work surface, cross-contamination of an ingredient on
a packing line or inhaling small airborne particles of the food
can be enough to trigger a reaction.
- Age. Food allergies are most common in babies and infants
due to their immature immune and digestive systems. Fortunately,
in most cases the child will out-grow the allergy, usually by
the age of 4 years—as is usually the case with egg, milk, soy
and wheat. But only about 20% of people with allergies to fish
or shellfish, peanuts or tree nuts outgrow the allergy—the
remaining 80% suffering a lifelong sensitivity to the particular
food.
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