Siblings and pets may reduce likelihood of egg allergy in infants

11 September 2012

Having a dog that lives in the home and older siblings could reduce the likelihood of egg allergies in infants, a new study by Murdoch Childrens Research Institute has found.

The study of over 5000 infants investigated the role a wide range of environmental and demographic factors has on the development of egg allergy.  This included number of older siblings, contact with other children during childcare, exposure to pets, caesarean delivery, infant diet, parents' country of birth, family history of allergy and the use of antibiotics in infancy.

The study found that infants with siblings, particularly young siblings, and infants with a pet dog inside the home, are less likely to be allergic to egg at one year of age.  In the study, 10.8% of infants with no siblings were allergic to egg, however as the number of siblings increased, the incidence of egg allergy decreased; the rate of egg allergies in infants who had three or more siblings was only 3.7%.  Among infants with one or more siblings, those with siblings under the age of six years old were less likely to have egg allergy compared to those with siblings six years or above.

Researchers also found a link to dog ownership, with the rate of egg allergies in infants who had no dogs at 10.2%, while among those who had a dog which was allowed inside the house, the rate of allergies dropped to 5.9%. 

Lead researcher, Doctor Jennifer Koplin said the findings provide further support for a role of the hygiene hypothesis, in combination with genetic factors, in the development of allergies.

"Our study showed exposure in the first year of life to siblings and dogs may decrease the risk of subsequent egg allergy.  This could be due to the fact contact with young siblings and pets may have a protective effect by exposing children to infections and germs."   

The study showed evidence of a protective effect of having a dog inside the house on egg allergy, even among those with those with no family history of allergic disease. 

The study, which was published online today in the journal, Allergy, also found the strongest risk factor for egg allergy was having one or more parents born in East Asia.  Interestingly, parents born in East Asia were less likely to report a history of allergies themselves, while their infants were at an increased risk of egg allergy and eczema. 

Principal Investigator Professor Katie Allen said to date risk factors for egg allergy have remained largely unknown, and by understanding these, it may be valuable in understanding the development for other allergic diseases later in life.  
 
"We have previously shown that later introduction of egg is strongly associated with risk of egg allergy, combined with this knowledge, these new findings and our other allergy research, we are adding to a growing amount of evidence which is starting to identify possible causes of allergies."

Read the full paper here.

Reducing the chance of food allergy developing in children


As a parent, you want to know whether you should act now to change factors in your life to prevent your children from developing food allergy.  There are theories about why food allergies are more prevalent. So the advice to patients, and to you, to prevent food allergy in your child are only recommendations based on the latest and best data available.

Professor Katie Allen, along with A/Professor Mimi Tang have written a book titled 'Kid's Food Allergies for Dummies', which outlines the below four simple steps you can take to help prevent food allergy in your child.

1.    Breastfeed for at least six months

If you can breastfeed (and we understand not all mothers are able to), we advise that you do so until your baby is at least six months old, because some evidence suggests that breastfeeding for the first four months of life and also introducing a food while your baby is still breastfeeding may prevent food allergy.

2.    Introduce solids at around six months

We recommend that you expose your baby to a wide and varied diet early on - at around four to six months of age.  If your child hasn't experienced an allergic reaction to a food, no reason exists to avoid any particular food with the hope of preventing an allergy.

3.    Let babies get down and dirty

Some evidence suggests that people in westernized countries need to expose themselves to more (healthy) bugs rather than stay too clean.  Evolving evidence suggests that children exposed to a broad range of 'good bugs' may be protected against food allergy.

4.    Get some sunshine in your life

Evolving evidence suggests that children without enough vitamin D (either through insufficient sun exposure or through a deficient diet) are at increased risk of food allergy.  Try to optimise your child's exposure to sunlight and increase vitamin D intake through diet. 


*Excerpt taken from Chapter 3 - Preventing Food Allergy in Kids*