Question:
And in the case of food allergies, was the child definitely exposed to
the food before they ever had allergic symptoms to it? I worry about our kids developing asthma and wonder if there is a
"safety" age when they might become less likely to develop it.
How can a child happily eat, for example, peanuts, for years and then
suddenly develop a severe allergy?
Answer:
I think the consensus is, the later you introduce solids the better (at
age 6 months is now recommended by many bodies including WHO I think).
Start with the foods people are less likely to react to like rice
cereal, pears, squash, etc. I think asthma is a special case and no one really knows all the causes
for it, some of it may be related to food allergies but some attacks are
brought on by environmental factors like dust.
For severe peanut allergies I think that it shows up the first time the
child is exposed. I don't think you can eat peanuts for years then
become severely allergic to them.
A true allergy requires that the child have been exposed
first. It simply takes an exposure for the immune system to
"prime the pump," if you will. In cases where people think that
the reaction happened on first exposure, the child was likely
exposed unknowingly (food hidden in something else, child grabbing
food when the parents were unaware, etc.), exposed through breastmilk
or while in utero, or exposed to a very similar food containing the
same proteins. There isn't, really. Adults can develop asthma without
previously having had obvious issues. I don't know when my
son's asthma started, but it was diagnosed when he was around
four years old. I have known others who were diagnosed much
earlier or much later. That said, the immune system isn't fully
matured until, what? something like six years old? Prior to that
it's somewhat easier to provoke the immature immune system into
a reaction that might not happen with a more mature immune system;
however, the immune system does need a certain degree of stimulation
in order to develop properly, so you can't keep your child in a
bubble while young so as to avoid atopic disease in the future.
Also, airways are so much smaller in infants and younger children
that a little bit of inflammation can manifest much more severely
than in an older child with larger airways. Do you know of an example where someone was able to eat
peanuts for years and suddenly developed a severe allergy to them?
I would think that particular case is quite uncommon. As far as
other allergies go, you have to have an exposure sufficient to
push the immune system "over the edge" before it starts wigging
out. I can only answer to the asthma part. My 13 yr old daughter was fine until
the age of two when we put her in the bottom bunk with her brother on the
top. They were new beds but old mattresses. The next morning, she woke up
with her face all swollen and having difficulty breathing. The consensus was
that whenever her brother moved on the above mattress, he dropped dust or
dust mite whatever over her. She had her first asthma attack then and has
been a moderate asthmatic since. I know it would have happened eventually
even if she hadn't slept on that bottom bunk, this just triggered it
earlier. Allergies (which may are may NOT trigger asthma or eczema) can show up
at any time of life. Yes, you can eat a food safely for years and then
develop an allergy to it. However, you can minimize the risk to your
children by:
- breastfeeding (without formula supplementation)
- delaying the introduction of solids beyond 6 months
- exposing your child to farm animals during the first 6
months of life (according to recent research)
- sending your child to daycare in the first 6 months of life
(although no one is quite sure why -- getting sick a lot seems
to be the correlate)
- delaying the introduction of non-human milk protein and wheat
past 10 months
- delaying the introduction of the most highly allergenic foods
(eggs, fish, shellfish, nuts, milk, wheat) beyond 12 months
I don't have the cites for all this information, but DID have the cites
before my hard drive crashed ...
Anecdotally, since you asked, one child has asthma but it is NOT
allergy-triggered. Diagnosed at 6 years of age, probably present for 2
years before that. One child developed soy allergy at 4 months (first
exposure was several ounces of supplementation in the first week of
life), egg allergy (breastmilk sensitized) that showed at 13 months but
then went away, and shellfish allergy (breastmilk sensitized) that
showed at 14 months and is still present at 5 years of age. My husband
developed milk allergy at the age of 23; my mother and grandmother
developed allergies to shellfish (one fish at a time, cumulatively) in
their 60's.
