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 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 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 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 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, 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. 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 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, 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 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 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. 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.
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.