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Wednesday, February 27, 2013

Environment and Demographic Risk Factors for Egg Allergy

Egg allergies are one of the most common food allergies among young children.  A recent study of about five thousand infants in Australia looked at the incidence of egg allergies at twelve months of age.

Research Question: 
What are the common factors in egg allergic infants?

Families enrolled in the study were asked to complete a questionnaire about their child’s eating habits and reactions to eggs.  Allergy skin testing was also performed on the children.

Out of 5276 children surveyed, 873 were skin test positive to egg white.  699 underwent an egg challenge (given egg to eat in the doctor’s office to see if they had symptoms of an allergic reaction). This would help to determine who exactly had an egg allergy. 
453 of these children had confirmed egg allergy (8.6% of all children in the survey).

Researchers then looked for factors that the egg allergic children had in common.

Children were less likely to have an egg allergy at one year of age if they had older siblings and if there was a dog in the house.

Children were more likely to have an egg allergy if someone in their immediate family (parent or sibling) had allergies.

Children whose parent or parents were born in East Asia were most likely to have an egg allergy.  Although the parents themselves are less likely to have allergies, their children are more likely to have eczema and egg allergy.

Children who live with a dog and who have older siblings have a lower chance of developing egg allergy. Living with pets and older children may expose a baby to viruses and bacteria that help develop a healthy immune system. 

The childhood environment of a baby’s parents may also play a role in the child’s immune system.  In this study, children whose parents were born in East Asia were at highest risk of having an egg allergy.

Environmental and demographic risk factors for egg allergy in a population-based study of infants. Koplin JJ, Dharmage SC, Ponsonby AL, Tang ML, Lowe AJ, Gurrin LC, Osborne NJ, Martin PE, Robinson MN, Wake M, Hill DJ, Allen KJ; HealthNuts Investigators.Allergy. 2012 Nov;67(11):1415-22. doi: 10.1111/all.12015. Epub 2012 Sep 7.

Wednesday, February 13, 2013

Caesarean births and formula feeding affect infant gut bacteria.

Many babies in developed countries are born by elective caesarean section and are formula fed instead of breast-fed. This may affect the type and amount of bacteria found in a baby’s gut.

Bacteria in the gut play an important role in human health especially the developing immune system. Disruption of the gut bacteria could increase risk for diseases such as allergies and asthma.

The development of the bacteria in an infant’s gut is not yet fully understood. The first North American study, to look at the infant gut is the Canadian Health Infant Longitudinal Development (CHILD) Study, a birth cohort involving 3500 newborn infants.

Research question: 
Does being born by caesarean section affect the bacteria in the guts of babies? 
Does breast-feeding vs. bottle-feeding affect the bacteria in the guts of babies?

The study looked at data for 24 healthy infants. 
Of this infant sample:
·         25% were born by caesarean delivery, 75% were born vaginally
·         42% were breastfed until 4 months of age, 58% were formula fed

Fecal samples (stool) from each infant were collected at 4 months of age.
The stool was analyzed to determine the kind and amount of bacteria in the gut.  

  • Children born by c-section had a different variety of bacteria, including lower amounts of particular good bacteria.
  • Children who were formula fed had a higher amount of less desirable gut bacteria.

These differences found in the gut bacteria, may explain why infants born through caesarean delivery are at higher risk of some childhood diseases, like asthma, allergies and obesity. Breastfeeding helps protect against these diseases.

Conclusion: The method of delivery and the type of feeding can affect a child’s gut bacteria and future health. It is important to take these differences into consideration when parents and doctors make decisions about the mode of delivery for an infant and how to feed in early life.

Check out these links for more related articles.