The Increasing Prevalence of Allergies

An allergy is a strong reaction by the immune system to a foreign substance, which can enter into the body through a variety of different routes.

It can be inhaled, like pollen or dander or it can be injected, like insect venom or penicillin, or merely touch the skin, like the latex in surgical gloves. Or it can be ingested through food, like milk, eggs, peanuts, tree nuts, fin fish, shellfish, soy and wheat.

Allergies are becoming more and more common because of various reasons.

The single most important risk factor responsible for developing allergic reactions is being born to a mother or father who himself or herself has an allergic disease.

However, there has been a noticeable rise in the number of people suffering from allergies within just one generation and, as it is known that changes in the genetic make-up of a population takes many generations to occur, other factors must also be involved.

One of these factors is infant feeding. When babies are exposed to food allergens such as cows’ milk and eggs earlier in life they are more likely to develop allergic disease. Breast-feeding does not wholly protect the baby because allergens from food eaten by the mother can be secreted in breast milk.

Although studies suggest that solid food should not be introduced before the age of four, many babies are given solids rather earlier. The diet in the West contains large amounts of commercially prepared food containing preservatives and other chemicals, and less quantities of foodstuff such as fresh fruit and vegetables that contain protective antioxidants.

Antioxidants are substances that reduce the rate of breakdown of another substance by oxidation. Delaying the introduction of solid food to infants appears to protect against allergies, especially eczema. The occurrence of eczema by age two is directly related to the number of different solid foods eaten by the baby before the age of four months. If a breast-feeding mother herself avoids allergenic foods such as milk, eggs, peanuts and fish, an extra defensive effect is seen.

Exposure to high levels of air-borne allergens in the early life has been seen to increase an infant’s risk of developing allergic disease. Babies born in the season of spring when the pollen count is high are more likely to be allergic to plant pollens at age ten than children born at other times of the year.

Similarly, babies exposed to pet allergens in earlier in life have an increased risk of allergy. Although being sensitive may occur at any age, the first year of life is particularly important, and there is much evidence that proves that exposures in mid and late pregnancy are also significant.

Exposure to tobacco smoke before, via the mother’s bloodstream, and after birth is strongly linked to the development of allergies and allergic disease, particularly asthma. Exposure to smoke after birth increases the risk; children living in smoking environs are twice as likely to be admitted to hospital with chest illness as children living in non-smoking families.

These children also have considerably reduced lung functioning by the age of seven. Passive tobacco smoke exposure is the strongest known risk factor for the increase of allergic diseases and so it is especially alarming to see that smoking is still rising in popularity in young women of childbearing age.

European children spend approximately ninety per cent of their time indoors so the indoor environment is perhaps more important than other outdoor environmental factors. Modern buildings are made to be insulated and have poor levels of ventilation, and these factors prove to be risk factors for the development of allergies.

This may be the result of high levels of chemical fumes from materials such as plastics and synthetic paints, high humidity resulting in indoor mould growth and increased levels of house-dust mite allergen. These living conditions seem to exert a very powerful effect in children already at risk because of a family history of asthma.

Clear evidence has been found that repeated viral and bacterial infections in early life may protect against the development of atopy and allergic diseases. Early life infections support the production of a chemical called interferon-gamma, which is found in higher levels in non-allergic people than in allergic people.

If children develop lower levels of interferon-gamma because of the protection they get from catching minor infections when they are young, their chances of developing an allergy might be increasing inadvertently.

An excessive intake of antibiotics has a similar effect. In contrast, children who have large numbers of older brothers and sisters, and who go to daycare centres where they mix with many other children and their germs, are less likely to develop hay fever and asthma.

The Western diet, with the use of formula milk and the early introduction of solid foods, in combination with the Western lifestyle being followed, like an early life exposure to tobacco smoke, high levels of plant and animal allergens, house-dust mite, living in poorly ventilated humid houses, having smaller families and delayed use of child-care centres all conspire to increase the number of people developing allergic diseases.