What is the link between the organisms in an infant’s gut and asthma and allergies?

A community of bacteria and other small organisms is a "microbiome". The gut microbiome is different in children with food allergies, asthma and eczema.

That means they may have fewer, or different, organisms living inside their intestinal tract than other infants.

Researchers have found some factors that are associated with a different microbiome in infants. They include:

• Vaginal birth
• Breastfeeding
• Having dogs in the house
• Using fewer antibiotics

Two recent studies looked at this issue in more detail. It is very important to note that studies have not proven a definite cause and effect as of yet. Thus far, studies have only been able to see if differences occur based upon various associations. There are likely other factors involved, some which may impact the microbiome directly.

One study found that children receiving an antibiotic treatment within their first year of life had a higher risk of food allergy.

University of South Carolina researchers looked at medical records from about 1,500 children with a food allergy diagnosis. They also looked at about 6,000 children without a food allergy diagnosis. Children who receive antibiotics within their first year were 1.21 times more likely to develop a food allergy than children who had not.

Children who received five or more prescriptions had an even greater risk of a food allergy diagnosis. Children who received stronger versions of antibiotics also had a greater risk.

Another study found a certain microbiome pattern in infants 1 month old could predict a higher risk of allergies by age 2. This pattern could predict asthma by age 4. These babies did not have high levels of a key immune cell that helps to prevent allergy.

Understanding more about how the microbiome works could help researchers develop ways to prevent allergy and asthma in high-risk babies.

References:

Fujimura, K.E. et al. (2016) Neonatal gut microbiota associates with childhood multi-sensitized atopy and T-cell differentiation. Nature Medicine.

Love, B. et al. (2016). Antibiotic prescription and food allergy in young children. Allergy, Asthma & Clinical Immunology.

Medical Review November 2016.