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Allergy is spreading throughout the population at an alarming rate. At present, one in four British people suffer from an allergy, or have done at some time in their lives. Each year, the number of UK allergy sufferers increases by 5%. Over the past 20 years, the number of people with allergies has increased fourfold. More than nine million of us suffer from hay fever, and more than one million people suffer from a food allergy.
The reasons behind the spread of allergies are not fully understood. This is not surprising, because we don't fully understand why some people are susceptible to allergies and others are not. We don't know, for example, why males are more likely to become allergic than females are, or why small families are more allergy-prone than larger families.
But in general, theories tend to link the allergy epidemic to our over-protected Western lifestyles and increased air pollution.
•
The hygiene theory
Scientists believe that the seeds for allergies are sown in childhood.
When we are children, we all have a tendency to manufacture E-antibodies.
Gradually, through exposure, the body learns to differentiate between
invasions by parasites and invasions by bacteria and other infections.
It learns to make other antibodies. But in the case of children who are
over-protected from dirt and disease, it is thought, the body never learns
to make these other antibodies to deal with infections and bacteria. In
contrast, living on a farm, particularly a livestock farm, is thought
to prevent allergies developing, because of exposure to certain bacteria.
The hygiene theory explains why people with a Western lifestyle are more
likely to develop allergic reactions.
•
Pollution
Scientists believe that over-exposure to some types of dirt and air pollution
may also promote allergies. The environment during the first year of a
child's life is thought to be crucial. If a child is exposed frequently
to cigarette smoke, pets, pollen and other potential allergens, they are
more likely to develop allergies later. There is evidence connecting air
pollution with a number of respiratory disorders, as well as conditions
such as eczema. Air pollutants in house dust are also thought to be a
major factor in the development of allergies.
•
Family traits
For some people, neither the right upbringing nor clean air will suffice
to protect them from allergy. People with atopy, an inherited condition
which increases the likelihood of developing allergies, are genetically
predisposed to suffer from conditions such as asthma, eczema, hay fever
and hives. Not all atopic people will develop these conditions, but they
are more likely than other people to do so.
•
The Allergic March
'The Allergic March' is the term used to describe the way in which allergies
develop over a person's lifespan. Not all allergies last a lifetime, and
some occur earlier than others. Children under the age of three are most
likely to suffer from food allergies and eczema. Allergy to egg white
is common at this age, but is unlikely to persist beyond the earliest
years of life. Asthma is most common in pre-pubescent children; hay fever
is most common in adolescence. Some allergies, such as food allergies
developed in adulthood, are likely to last for life, however.
The immune system | Common allergies
Allergic reactions | Allergic people
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