This section covers allergy and intolerance, ingested (food), inhaled and contact. Please click on the aspect of the conditions that interests you in the left hand navigation bar.
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Allergy
The earliest definition of 'allergy' was an
'inappropriate response by the body to a perfectly harmless substance'.
In modern
medical parlance, however, allergy has come to be more narrowly
defined: a specific response by the immune system to a substance
(inhaled, touched or eaten) which it mistakenly identifies
as harmful.
Contact with this substance triggers the release
of IgE antibodies which attach to 'mast' cells and, in turn,
precipitate a release of histamine, the chemical which causes a contraction
of the muscles around the air passages (an attack of breathlessness
or
asthma), local swelling and skin irritation, and, if the attack
is serious enough, a drop in blood pressure.
Research is ongoing to find a way of preventing the
immune system making these mis-identifications but until a breakthrough
is achieved, the only treatment for allergy is avoidance of the allergen
combined with the use of adrenaline (epinephrine) to countract the
release of histamine in more serious attacks. See the articles under anaphylaxis.
Intolerance and sensitivity
Although the medical profession
is very clear about what it means by allergy, the general population is a
lot less so and use the term to cover any sort of adverse reaction to almost
anything.
Many people certainly do suffer adverse reactions
to substances, particularly foods, which have not sparked an immune
system response. These responses are normally classed as intolerances
or sensitivities and have a very wide range of
causes, symptoms and degrees of severity. However, they nearly
always manifest as part of (a result or symptom of) some other
medical condition or illness.
Some conditions, such as coeliac
disease or phenylketonuria are
caused by specific foods or food components.
More frequently specific foods may be poorly tolerated
because of some underlying condition. Thus IBS sufferers,
find
that specific
foods
trigger
reactions;
for sufferers
from Crohn's specific foods irritate
their condition; migraine sufferers may find that specific
foods trigger attacks; some mental health conditions such as
depression can be made better/worse by certain foods etc
The amount of the food needed to cause a reaction
and the length of time it takes to do so will vary hugely. Moreover,
in many cases, as the underlying health condition improves, so does
the person's ability to tolerate a food which had previously upset
them.
The articles in this section cover both allergies
and intolerances. You wil also find allergy related articles in almost
every other section.
NB Information on this site is not a substitute for medical advice and no liability can be assumed for its use.
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