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Food Allergies: Race, Ancestry Matters?

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By Dr. Levister

There's a possible link between race and food allergies in children. A study of two-year-olds showed African-American children were twice as likely as white children to have an immune response to foods such as peanuts and milk. Researchers looked at the kids' DNA and found that the more African ancestry it showed, the more likely a child was to have any type of food sensitization, especially to peanuts.

But it's still unclear why that's the case, they said. It could be that differences in genes make some kids more likely than others to get allergies, or it may have to do with their environment and what they're exposed to early in life. The study included about 1,100 kids, all born at Boston Medical Center. Between two and three years after birth, researchers led by Dr. Rajesh Kumar of Children's Memorial Hospital in Chicago brought them in to test their immune responses to eight different types of foods that typically cause allergies: eggs, milk, peanuts, soy, shrimp, walnuts, wheat and cod.

Most kids in the study were from urban areas and many were from low-income families. About six in ten of them were identified as black by their moms. In all, just over one-third of kids had an immune response to at least one of the foods, the researchers reported in the Journal Pediatrics. About 38 percent of black kids had a food sensitization, compared to 22 percent of white kids. When the researchers took into account factors like whether or not kids were breastfed and if moms smoked while they were pregnant, the black two-year-olds were at greater risk for a food sensitization.

Food sensitizations were also more common in kids whose ancestors were mostly from Africa, compared to those of European descent, according to genetic tests. There were some differences between kids whose moms reported their race as black and those who had more gene markers suggesting African descent. For example, African ancestry was linked to a greater chance of having a high immune response to peanuts, whereas black race was not.

That tells researchers that genetics may play a role in how likely kids are to have food sensitizations or allergies. Or, something about different ancestral environments may be playing a role, Kumar said -- for example, people from Africa are known to have lower vitamin D levels early in life. Vitamin D has been linked to some aspects of immune function.

On another level, cultural factors such as what type of foods kids are exposed to when they're young, or where they grow up, might trigger allergies, especially if there is already an underlying race-related genetic susceptibility, Joseph said. More research is needed to better determine what's behind these differences in risk, both by race and ancestry, they agreed.

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