What is anallergy? It is a major defence mountedby the body's immune systemagainst normally harmless substances, or allergens, such as chemicals in pollen, food,bee stings, animal dander, or dust. An allergic reaction is the body's strongreaction to these substances in a person who is sensitive to them. An allergy is everything from a runnynose, itchy eyes and palate to skin rash. It aggravates the sense of smell,sight, tastes and touch causing irritation, extreme disability and sometimesfatality. It occurs when the body's immune system overreacts to normallyharmless substances.
Almost anythingcan be an allergen for someone. Allergens contain protein, which is oftenregarded as a constituent of the food we eat. In fact, it is an organiccompound, containing hydrogen, oxygen and nitrogen, which form an importantpart of living organisms.
The most commonallergens are: pollen from trees and grasses, house dust mite, moulds, petssuch as cats and dogs, insects like wasps and bees, industrial and householdchemicals, medicines, and foods such as milk and eggs. Less common allergensinclude nuts, fruit and latex.
There are somenon-protein allergens, which include drugs such as penicillin. For these tocause an allergic response they need to be bound to a protein once they are inthe body.
An allergicperson's immune system believes allergens to be damaging and so produces aspecial type of antibody (IgE) to attack the invading material. This leadsother blood cells to release further chemicals (including histamine) whichtogether cause the symptoms of an allergic reaction.
Appreciate whenasthma, eczema, headaches, lethargy, loss of concentration and sensitivity toeveryday foods such as cheese, fish and fruit are taken into account the fullscale of allergy.
Who are prone tobe a sufferer of allergy reactions? The answer is three-fold. First, your genetic background plays a major role - we know that afamily history of allergies or "Atopy" is highly significant, smallerfamilies with fewer children favour the development of allergy. Males are morelikely to develop allergies than females, and prenatal maternal diet and smokingseem to play a role. Obesity also seems to be a risk factor for developingallergies.
In the second place,the home environment in the first year of life is pivotal. Parental cigarettesmoking triggers allergy, Infant diet, and early introduction of allergenicfoods play a role. Air Pollution has been implicated; early use of day-careinstitutions, early use of broad-spectrum antibiotics and birth just before thespring pollen season all seem to promote allergic sensitisation. Recent studiessuggest that heavy exposure to dog and cat allergens in the home may actuallyprevent allergies developing in infants (they suggest having two or more petsin the home!)
Finally, modest exposure tothe common aeroallergens and allergenic foods in conjunction with these other factors leads to sensitisation in earlylife and clinical allergy then develops. Modest early exposure seems tobe the key to triggering sensitisation, as evidence now exists for very highallergen exposure during early life having a "protective" effect (forexample to cats and dogs). However, minimal exposure during the first year oflife is still the recommended "rule of thumb" for allergy prevention.
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