Why are allergies on the rise? Why do so many children and adults have food allergies, asthma and hay fever? What are we doing wrong?
Delivery by C section seems to increase risk for allergies in children. Passing through the birth canal with exposure to bacteria may be good for shaping our immune system.
Feeding infant formula leads to a less favorable composition of intestinal flora in the infant. Breastfed children develop less upper respiratory infections, early wheezing and less eczema.
Early use of antacids for reflux reduce the breakdown of proteins in the stomach. Therefore more whole proteins will be absorbed from the gut and may induce allergies.
Antibiotics can change the composition of “the good bacteria” in our gut. And these changes can lead to higher risk of allergies particularly in the immature immune system of young children.
RSV and rhinovirus (two common cold viruses) are linked to development of asthma and early wheezing in children.
For many years the AAP guidelines recommended to delay introduction of certain foods (milk after 1 year, egg after 2 years, etc). Newer studies however show that late introduction may lead to more allergies. Particularly peanut allergies are more common in the USA compared to other countries (Israel) where they did not go by these earlier guidelines.
Vitamin D deficiency is a problem particularly in darker skin individuals or babies who are not exposed to sunlight and increases risk for asthma, skin and other allergies.
The hygiene hypothesis suggests that children growing up on farms and who are regularly exposed to farm animals have a lower risk of allergic diseases. Therefore having certain pets (dogs) early in life may be protective.
Cockroach and dust mite allergen in particular seem to be an early risk factor for development of allergies. Cockroach is an important inner city allergen and responsible for a large part of inner city asthma.
Parental smoking and home smoke exposure leads to increased respiratory disorders in children including allergies and asthma
Of course this list is by far not complete. Other factors such as pollution and dietary factors beyond Vitamin D intake also play a role. For more detailed information you can read a great summary in the New England Journal of Medicine from 2006.
As you can see from this list, our immune system gets shaped early in life. For some of these points we have no choice of changing them: C sections are often necessary for the safety of the child or the mother. There are however people (we hear about actresses in the glossy magazines) who schedule C sections without any indication another than preference for a set date and not having to go through labor. Some mothers are just not able to breastfeed despite their best intentions. But there was a time in the 70s when breastfeeding was considered inferior to formula. Not every ear infection needs to be treated with antibiotics and not every fussy child needs an antacids. Knowing the risk factors may help you make modifications and “shape the future of your child”.