Why Do People Get Adult-Onset Food Allergies?

New research indicates that adult-onset food allergies are more common than previously thought. But why do they happen? Learn more on BrainStuff.

Learn more about your ad-choices at https://www.iheartpodcastnetwork.com

See omnystudio.com/listener for privacy information.

Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from How Stuff Works High Brain
Stuff Lauren Vogel bomb Here, we often think of food
allergies as kids stuff. You know, a peanut free elementary
school classrooms, a special carton of dairy free ice cream
at birthday parties, and that one friend who couldn't eat
anything containing red food die, which meant you got all
their primo Halloween candy. But we don't always develop our

(00:24):
allergies as children. It's just that childhood food allergies are
studied more often than those acquired in adulthood. However, new
research presented at the annual meeting of the American College
of Allergy, Asthma and Immunology found that of all American
adults with food allergies have at least one allergy that
only materialized in adulthood. In the Chicago based research team

(00:46):
found that at least fifteen percent of adult food allergy
patients receiving care at Northwestern Medicine had at least one
adult onset food allergy. However, this was a small, non
representative sample of just Chicago area adults for this new study,
these of it a nationally representative sample of more than
fifty thousand adults, allowing the researchers to draw conclusions about
the national prevalence of adult onset food allergies, and it's

(01:09):
a lot higher than anyone anticipated given studies from previous decades.
The research team notes that while a two thousand four
study estimated that two point five percent of adult Americans
were allergic to shellfish, the most common food allergy among
adults in the United States, this twenty seventeen study found
that number is more like three point six percent of
the population. The same goes with tree nut allergies. A

(01:30):
two thousand eight study estimated that only zero point five
percent of American adults were allergic, but this new data
saw a two hundred and sixty percent increase, with an
estimated one point eight percent of adults having to avoid
everything from ntella to Reese's peanut buttercups. We spoke with
one of the studies co authors, Christopher Warren, whose a
doctoral candidate in preventative medicine at the University of Southern California,

(01:51):
via email. He said adult onset allergies are particularly interesting
to study because they likely involve losing immune tolerance to
foods that adults have already been previously exposed to and
eaten without having an allergic reaction. This is in contrast
to childhood food allergies, which involve the immune system failing
to develop tolerance to these allergic foods in the first place.

(02:11):
There may be two distinct mechanisms at work here. So
why would adults be losing their immunity chops when it
comes to certain foods. A possible clue might lie in
the demographic trends found in the study. The research team
found that certain populations were more at risk for specific
adult onset food allergies than others. For instance, Hispanic adults
were more than twice as likely to develop allergies to

(02:33):
peanuts than whites, and Asians were more than twice as
likely to develop shellfish allergies than whites. Warren said that
there are a number of hypotheses for why this may be.
For example, the cultural differences in the way that people
of different backgrounds prepare allergenic foods could possibly influence the
rates of allergies to those foods. According to Warren, when
foods like peanuts are roasted in the presence of sugar,

(02:54):
undergoing a browning process known as the Millard reaction, compounds
called advanced glycati and end products are created. These compounds
have been shown to increase the allergenicity of foods. Boiling foods,
on the other hand, tends to make their proteins less allergenic.
This hypothesis may explain the low rates of peanut allergy
in Asia, where peanuts are typically boiled or fried, relative

(03:15):
to the Americas, where peanuts are typically dry roasted. This
is consistent with what the current research team found out
about the prevalence of seafood allergies among Asian American participants.
Other population based studies conducted in Asia have found that
shellfish allergies are the most common allergy among older children
and adults there as well. However, diet might not have
everything to do with why certain populations develop allergies to

(03:38):
specific foods with higher frequency. Warren told us about an
ongoing study into the allergies of over five thousand children
that's being conducted in Australia called health Nuts. He said
a recent work out of the Health Nuts cohort in
Australia suggests that the Asian environment may be protective against
food allergy. Australian born Asian children are at a much
higher risk of developing food allergies than Asian born kids.

(04:00):
It's who moved to Australia, possibly because they've been exposed
to a different diet, bacterial, and uv environment. Warren and
his co authors are interested in looking at differences in
food allergy prevalence in the United States to see if
similar differences are observable among US immigrants relative to those
born in the States. We'll be on the lookout for updates.

(04:23):
Today's episode was written by Jesslyn Shields and produced by
Tristan McNeil. For more on this and lots of other
health topics, visit our home planet, how Stuff Works dot com.