A decade after groundbreaking research demonstrated that introducing peanut products to infants could prevent severe allergies, new findings highlight the real-world impact of this practice.

In the United States, peanut allergies have been on the decline since a 2015 guideline shift recommended exposing infants to peanuts as early as four months old, challenging previous medical conventions.

The incidence of peanut allergies among children aged 0 to 3 dropped by over 27% following the 2015 guidance for high-risk children. This rate further decreased by more than 40% after the recommendations were broadened in 2017.

“Isn’t that remarkable?” remarked Dr. David Hill, an allergist and researcher at the Children’s Hospital of Philadelphia, who authored a study published Monday in the journal Pediatrics.

Dr. Hill and his team examined electronic health records from numerous pediatric practices to monitor food allergy diagnoses in young children before, during, and after the issuance of these guidelines.

“I can actually come to you today and say there are less kids with food allergy today than there would have been if we hadn’t implemented this public health effort,” he added.

About 60,000 children have avoided food allergies since 2015, including 40,000 children who otherwise would have developed peanut allergies.

Still, about 8 per cent of children are affected by food allergies, including more than 2 per cent with a peanut allergy.

Peanut allergy is caused when the body’s immune system mistakenly identifies proteins in peanuts as harmful and releases chemicals that trigger allergic symptoms, including hives, respiratory symptoms and, sometimes, life-threatening anaphylaxis.

For decades, doctors had recommended delaying feeding children peanuts and other foods likely to trigger allergies until age 3.

But in 2015, Gideon Lack at King’s College London, published the groundbreaking Learning Early About Peanut Allergy, or LEAP, trial.

Lack and colleagues showed that introducing peanut products in infancy reduced the future risk of developing food allergies by more than 80 per cent.

Later analysis showed that the protection persisted in about 70 per cent of kids into adolescence.

The study immediately sparked new guidelines urging early introduction of peanuts — but putting them into practice has been slow.

Only about 29 per cent of pediatricians and 65 per cent of allergists reported following the expanded guidance issued in 2017, surveys found.

Confusion and uncertainty about the best way to introduce peanuts early in life led to the lag, according to a commentary that accompanied the study.

Early on, medical experts and parents alike questioned whether the practice could be adopted outside of tightly controlled clinical settings.

The data for the analysis came from a subset of participating practice sites and may not represent the entire US pediatric population, noted the commentary, led by Dr Ruchi Gupta, a child allergy expert at Northwestern University.

However, the new research offers “promising evidence that early allergen introduction is not only being adopted but may be making a measurable impact,” the authors concluded.

Advocates for the 33 million people in the US with food allergies welcomed signs that early introduction of peanut products is catching on.

“This research reinforces what we already know and underscores a meaningful opportunity to reduce the incidence and prevalence of peanut allergy nationwide,” said Sung Poblete, chief executive of the nonprofit group Food Allergy Research & Education, or FARE.

The new study emphasises the current guidance, updated in 2021, which calls for introducing peanuts and other major food allergens between four and six months, without prior screening or testing, Hill said.

Parents should consult their paediatricians about any questions.

“It doesn’t have to be a lot of the food, but little tastes of peanut butter, milk-based yogurt, soy-based yogurts and tree butters,” he said.

“These are really good ways to allow the immune system exposure to these allergenic foods in a safe way.”

Tiffany Leon, 36, a Maryland registered dietician and director at FARE, introduced peanuts and other allergens early to her two young sons.

At first, Leon’s own mother was shocked at the advice to feed babies such foods before the age of 3, she said.

But Leon explained how the science had changed.

“As a dietician, I practice evidence-based recommendations,” she said.

“So when someone told me, ‘This is how it’s done now, these are the new guidelines,’ I just though, OK, well, this is what we’re going to do.”

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education and the Robert Wood Johnson Foundation. The AP is solely responsible for all content.