Allergy Prevention in Children

1 Feb 2006 10:08 PM - Dr Roger Morris

Up to 40% of Australian children are affected by allergies at some time during their life. Allergic diseases have seemed to increase in prevalence in Western countries and their frequency has approximately doubled over the last 25 years. The most common allergic conditions in children are food allergies (which are much less common than many think), eczema, asthma and allergic rhinitis (hay fever). Allergies are caused by abnormal immune responses to otherwise harmless substances in the environment. These substances, called allergens, can enter the body through the respiratory system, gastrointestinal system, skin or eyes.

One theory used to explain this apparent increase in allergic disorders in Western societies is the ‘Hygiene Hypothesis', which postulates that an overly clean environment in early life may actually promote rather than inhibit the development of allergy. This has been supported by numerous studies that have demonstrated an apparent protective effect of fever and viral infection early in life (especially between the ages of 6-18 months) on the development of allergy and asthma by the age of 6-7 years. One recent study showed that the more viral-induced fevers experienced by children between 6-18 months (especially if these fevers were between 38-39 degC), the less chance of these children developing allergy and asthma later in life. This held true even when these results factored in family history of allergy and a myriad of other potential confounders. This supports earlier observation that the lower down the sibling line a child is, the less chance that child had of developing allergies or asthma (Strachan, 1989). This is thought to be due to younger siblings experiencing more viral infections early in life, caught from their older siblings.

There are a number of practical steps parents can take to lessen the chance their child will develop allergies and asthma later in childhood. This is especially important if there is a strong family history of allergic disorders. It should be emphasised that even if you apply the following suggestions, there is still a chance that a high risk child will develop allergies.

1. DO NOT SMOKE during pregnancy, in the presence of a child or in enclosed spaces where a child sleeps or plays.
    
2. A couple of studies have suggested that mothers with a strong history of allergy could consider taking FISH OIL supplements (Omega 3:6:9) or ‘PROBIOTIC' supplements (‘good bacteria' such as Acidophilus & Bifidus) during pregnancy to reduce the risk of allergy in their unborn child. This is a developing area.
    
3. BREAST FEEDING. Where possible, breast feed your child exclusively to at least the age of 4 months and possibly up to the age of 6 months. It is thought that exclusive breastfeeding protects against gastrointestinal infections in the baby and may prevent development of allergic disorders. Dietary restrictions during pregnancy and breastfeeding are not recommended due to a lack of proven benefit and the risk of nutrient deficiency.
    
4. If breast feeding is not possible, a hydrolysed (hypoallergenic) formula rather than conventional cow's milk formula is recommended for the first 6 months of life.
    
5. Delay the introduction of solid foods until the child is 6 months of age. Avoid potentially allergy provoking foods such as cow's milk and egg until after 12 months of age, and peanuts, nuts and shellfish until after 2-4 years of age.
    
6. Based on the mounting evidence supporting the ‘Hygiene Hypothesis', parents should not get to concerned about their child's exposure to common viral infections early in life. While remaining alert and cautious at all times, parents should not feel compelled to suppress fever during viral illness, as being overzealous with administration of antipyretics such as paracetamol and ibruprofen may reduce the immune response to infections, prolong their course and may reduce the protective effect of fever against later development of allergy and asthma.

Sources: Australasian Society of Clinical Immunology and Allergy (ASCIA)
http://www.allergy.org.au/

American Academy of Allergy, Asthma & Immunology (AAAAI)
http://www.aaaai.org/


Dr Roger Morris is a General Practitioner in Maroochydore, who has a special interest in Child & Adolescent Health.