I was recently stumped by a question: Why are so many babies born with food allergies especially when the parents don't have them themselves? For someone who has a wheat allergy, I can relate and wanted to get to the bottom of this. I too have noticed that friends and family members have children and shortly after birth find out they are allergic to milk, peanuts, gluten, etc. According to FARE (Food Allergy Research & Education), approximately 1 in every 13 children under 18 years old experience food allergies. I can understand as adults why we get food allergies due to the quality of our food and stress, however in children who have not been exposed to foods for the same length of time, and to foods other than breast milk, why is this happening? As I read some articles, epigenetics was a term that continually came up. Epigenetics is referring to the way our genes are expressed. If the coding in a gene reads one way and it expresses the way it is supposed to, environmental factors or diet can get in the way and change how that gene is expressed. For example, I never had an allergy to wheat growing up, however as I ate it over the years, it or stress changed the expression of my immune cells which now prevents my body from tolerating it. I came across one article on peanut allergies where they found links to genetic changes and hope in the future we may even be able to predict in utero what allergies a child could develop. But why so soon are babies developing allergies?
When it comes to passing down food allergies, I found another article that discussed reprogramming of genetics during pregnancy. In this process, no matter how epigenetics might exist in the parents, the genes are re-programmed in a way to erase or prevent those same effects from occurring in the child. On the other hand, there is also a process called imprinting that takes place, and some genes that are sure to be expressed in the child will not change during reprogramming, even if they have changed expression in the adult. So for example, the dad has a peanut allergy and the mom does not, but imprinting silences the mother's gene and the father's peanut allergy is then expressed in the child since it was not reprogrammed. But what if the parents don't have allergies?
While genetics can play a role in food allergies, the immune system is the main conversation since that's how your body responds to allergens. In today's world there are not many vaginal births and many mothers choose not to breast-feed. Both of these play a role in the development of a babies immune system. Vaginal births expose children to the good bacteria within the mother, and breast-feeding passes on anti-bodies and immune boosting qualities. The Hygiene Hypothesis also suggests we are not exposed to bacteria in the same way generations before us were. Many of us did not grow up on farms, but cities where farm animals and the allergens they carry are not surrounding us. As much as allergens can cause a reaction, early introduction helps build our immunity over time.
In conclusion, it seems that both genetics, environment, diet, and immunity are the commonalities attributing to food allergies. I would imagine just as a food allergy could be passed along to a child, so could any epigenetics effecting the parents' immune systems. There are many prescription drugs, especially antibiotics that deplete our immunity overtime, and if this too could change our genes it could make future offspring more susceptible to allergies and other sickness too through imprinting. For each child diagnosed with food allergies, it could be these individual factors that are causing them or it could be a combination of all. Hopefully more research will continue to be done, including techniques on how we can prevent this for children in the future.