The rise of food allergies and what researchers are doing to prevent them
When I was in grade school, there was no “peanut-free” table. Peanut butter sandwiches were traded freely for chocolate milk and potato chips. Birthdays meant cupcakes in the classroom, with little thought as to whether they were made in a peanut-free facility. To a kid today this sounds crazy — and for good reason.
From 1997 to 2007, the rate of food allergies increased 18 percent for children under 18 years of age, according to the Centers for Disease Control and Prevention. Today, food allergies — including the incredibly dangerous peanut allergy — affect 8 percent of American children. That’s about two in every classroom.
Why food allergies happen
As the incidence of food allergies has gone up, so has research to determine why they’re increasing and what can be done to protect children from developing them.
Eight foods account for approximately 90 percent of food allergies in the U.S.: peanuts (the most common), tree nuts, milk, eggs, shellfish, finned fish, soy and wheat.
Certain factors make a child high-risk and susceptible to the development of a peanut allergy, chief among them an egg allergy (one of the most common allergenic foods for infants, along with milk and peanuts) or prior eczema. Children with eczema have weakened skin barriers that can allow allergic antibodies to more easily enter the body.
An infant can be exposed to allergens through skin exposure long before an item is ever ingested. “The foods we eat get scattered in the dust in the house,” explains Mahboobeh Mahdavinia, MD, of the Immunology and Microbiology Department and Internal Medicine Department at Rush University Medical Center.
We actually have an opportunity to prevent peanut allergies.”
The gut microbiome may also play a role in the development of food allergies. The first year of life is a crucial time in the development of gut bacteria. Oversanitization — including use of antibiotic drugs in infancy and overuse of antibacterial soaps — may affect the delicate balance of gut bacteria, killing off good bacteria with the bad.
Contrary to what many parents believe, exposure to bacteria in things we consider “unclean” — dirt, animals, public sandboxes, etc. — is important for the development of a strong immune system. Exposure to bacteria helps train the immune system to fight off disease and not overreact when harmless substances are introduced.
Recommendations of when to introduce children to potentially allergenic foods has changed over the years. Early introduction, researchers say, reduces the risk of developing a peanut allergy.
“In 2000, the American Academy of Pediatrics (AAP) said not to introduce peanut products to infants until 3 years of age,” says Ruchi Gupta, MD, MPH, associate professor of pediatrics at Northwestern University Feinberg School of Medicine and director of its Science and Outcomes of Allergy and Asthma Research Program. The AAP retracted this recommendation in 2008 due to lack of data, but many parents held on to the idea.
Only now, Gupta says, does definitive research exist on when peanuts should be introduced: 4 to 6 months of age, under supervision, for high-risk children with severe eczema or egg allergy; 6 months of age for those with mild to moderate eczema; and freely introduced with other solid foods at any time for those not at risk.
In the groundbreaking Learning Early About Peanut (LEAP) study, published in 2015 in the New England Journal of Medicine, researchers examined 640 high-risk children between the ages of 4 and 11 months and assigned them to either consume or avoid peanuts until age 5.
Of those at-risk infants who avoided peanut consumption, 17 percent developed a peanut allergy by age 5; yet only 3 percent of those who ate peanut products developed the allergy. Ultimately, the study found that early, regular peanut consumption begun in infancy and continued until age 5 resulted in an 81 percent reduction in the rate of peanut allergy.
“We actually do have an opportunity to prevent peanut allergies,” Gupta says.
Other studies examining prevention are currently being done, including one, Mahdavinia says, that will attempt to use probiotics to correct the microbiome in children whose gut bacteria have been affected in the early years of life.
Another important emerging field is oral desensitization (also called oral immunotherapy) — the gradual introduction of peanuts to children who are allergic to them in a controlled environment under the supervision of an allergist. Though currently in clinical trials, early results have been promising. One study, partly supported by the National Institute of Allergy and Infectious Diseases, showed that nearly 80 percent of peanut-allergic preschoolers successfully incorporated peanuts into their diets after receiving oral immunotherapy.
As new developments emerge in our understanding of why food allergies develop and how we can prevent them, researchers offer hope that real change is possible. Given the progress already made, we may be facing a future when, once again, peanut butter sandwiches are a mainstay of the school lunchroom.
How to Introduce Peanuts to Your Child
Peanuts should be introduced to children early. Here’s how to do it safely.
Determine your child’s risk. Reactions are rare in low-risk children without eczema or egg allergy, Gupta says, so you’re fine to start the introduction at home. If you are concerned that your child may be high risk, talk to your doctor about allergy testing or introducing peanuts with an allergist.
Don’t start with peanuts. When your child is ready for solid foods, start with the basics. Gupta recommends beginning with cereal, then fruit and vegetables. A week or so later, start introducing peanut products. Do not introduce whole peanuts to infants, as they are a choking hazard.
Water it down. An infant can’t handle a spoonful of peanut butter. Take two teaspoons of peanut butter and liquify it with two to three teaspoons warm water, Gupta says. Feed two tablespoons of the liquified peanut butter to your child over the course of 20 minutes to an hour, or however long it takes them to finish. Observe your child closely and look for allergy warning signs, including hives, swelling, vomiting or difficulty breathing. If any of these occur, seek immediate medical attention.
Keep it in their diet. Once you’ve introduced peanuts to your child, continue to feed peanuts at least three times a week to maintain tolerance, Gupta says.
Don’t force it. If your child isn’t enjoying peanut butter, Gupta says, it’s okay to stop and try again at a later time. Just make sure you introduce it regularly during the important 4- to 6-month-old period. — L.D.