TIME recently published an article about a study that took place at Northwestern University Medical School, and I think it’s pretty relevant:
Dr. Rajesh Kumar, a pediatrician at Northwestern University Medical School, and his team report in the journal Pediatrics that black children are more than twice as likely as white children to have sensitivities to eight foods that commonly cause allergic reactions, and that they are especially vulnerable to peanut allergies.
While other studies have linked African American ethnicity to a higher risk of asthma, Kumar’s group was interested in investigating whether race also affects children’s risk of allergy to certain foods. Using a multi-ethnic database of 1,104 children who participated in regular health checkups at 6 months, then again at 1, 2, 4 and 6 years old, the scientists measured the youngsters’ antibodies to egg white, cow’s milk, peanut, soy, shrimp, walnut, wheat and cod.
To determine race, the researchers used two measures — the children’s mothers’ self-report of race as well as the distribution of 150 genetic markers in the children’s blood, which track ancestry. The researchers included the second, more objective measure because self-reports of race can often be inaccurate, especially given the amount of racial mixing that occurs in a country as diverse as the U.S.
“If you look at populations who describe themselves as one race like African American or Hispanic, they may have ancestors from different continental groups,” says Kumar. “So the description loses precision if you just use race. Whereas if you look at ancestry, you get a more precise proportion of what ancestors came from one continent compared to another.”
The researchers found that children whose mothers reported them as being black were nearly 2.5 times as likely as self-reported white youngsters to be sensitive to any of the eight foods tested, and they were also more likely to be sensitive to more of the foods than white children.
When the researchers looked at the genetic markers for ancestry, they found that for every 10% increment in African ancestry, children were 7% more likely to have antibodies to the allergy-causing foods than white children. And the association was strongest for peanuts; more children with African ancestry showed antibody levels that would correlate to a possible allergic reaction if they were to eat peanuts.
Kumar stresses that his findings do not suggest that black children with more African ancestry are likely to develop food allergies, or even a peanut allergy. His study was only able to find links between levels of antibodies that are likely to generate a reaction.
“This is one way for us to start teasing out why there are increased risks in this population,” he says. “What we did was confirm that, one, yes, there is increased risk among black children for food sensitization and, two, we are starting to get at why they are at increased risk.”
Although the genetic markers are likely to reflect some inherited factors that affect how the immune system reacts to foods, it’s also possible that they encompass environmental factors. For example, the children who self-reported themselves as black showed a stronger likelihood of sensitization to milk and egg allergens, but not to peanuts, while those with more African ancestry showed the opposite trend: they were more likely to be sensitive to peanuts but not to milk and egg.
“Overall, black children seem to be at higher risk of being sensitive to foods, but if you break down that risk, self-identifying as black explains the risk to milk and egg allergens but not to peanut, while ancestry explains some of the risk to peanut allergens,” says Kumar. “That may mean that different factors go along with an individual’s self-identified race compared to their genetic ancestry.”
These factors may include things such as the fact that newborns of African American ancestry tend to have lower vitamin D levels, which has been linked to an increased risk of allergic diseases. Or, that those who identify themselves as being black may adhere to cultural dictates for when babies are introduced to milk, which can affect how newborns’ immune systems react to it.
I’m trying to reconcile this with what I know, historically, to be true of peanuts, dairy and our lineage with both. Peanuts aren’t from Africa – but I’m trying to remember if we had experience with peanuts before we were brought over to the Americas. I know you guys thought it was strange when I posted Robyn O’Brien’s TEDx talk about nuts, allergies and processed food, but I’m with her. I think there’s something in the processing that is causing our bodis to treat this stuff as “foreign invaders.” And, trust me, I’m speaking from existence – I learned, the hard way, that I’m allergic to shrimp that’s been pre-shelled but uncooked because of the chemical they spray on it to keep it from spoiling. (Because no one will acknowledge – or admit – to me what that chemical is, I can’t identify it.) We weren’t eating dairy when we came over (I think there was only on tribe that drank the milk of other animals?), but we’ve been using peanuts in everything for ever. Why, all of a sudden, are all these allergies springing up?
Do you, or a child you love, have an allergy? What do you have to avoid? Are you only allowed to have your “allergic” food in some forms and not others, like me? I’d like to hear about it!