A new study on food allergies has found that as many as 1 in 20 children may develop a food allergy by age 6.
The research, published in JAMA Pediatrics, analyzed 190 studies of more than 2.7 million children across 40 countries and identified major and minor risk factors linked to food allergies.
It found about 5% of kids in the U.S. had a food allergy by the age of 6.
According to the study, some of the major risk factors included early allergic conditions such as asthma and eczema; antibiotic use in the first month of life; having parents with food or related allergies; delayed introduction of foods like egg, fish, fruit, and peanuts; identifying as Black; and having parents who migrated before birth.
Minor risk factors included being male, birth via cesarean section, being firstborn, and certain skin-barrier-related genetic differences.
The most common food allergens for children and babies include milk, eggs, peanuts, and shellfish, according to StatPearls, an online library published in the National Library of Medicine.
"The big thing researchers say is food allergies are not just genetic, it's multifactorial," ABC News chief medical correspondent Dr. Tara Narula, who was not involved with the study, explained this week. "It is genetics, plus environment, plus microbiome, plus, possibly, your skin health. All of that really put together, that might be causing food allergies."
While the research shows risk factor associations, it does not show direct cause and effect, and experts cannot determine how a combination of those risk factors work together.
Because a majority of the data came from high-income countries, this study has limitations on generalizability.
Not all the studies from the research confirmed food allergies using food challenge tests.
The recurring message that comes up in food allergy discussions, experts like Narula point out, is that "early introduction of those allergenic-type foods around 4 to 6 months, when kids start to eat solids, will be important for preventing the development of food allergies."
