Introducing peanut butter during infancy can help protect against a peanut allergy later on, new study finds

Reassuring new evidence suggests that feeding children smooth peanut butter during infancy and early childhood can help reduce their risk of developing a peanut allergy even years later.

Compared with avoiding peanuts, starting peanut consumption in infancy – as early as around 4 months of age, as a soft pureed paste, for instance – and continuing regularly to around 5 years old was associated with a 71% reduced rate of peanut allergy among adolescents in the United Kingdom, according to a study published Tuesday in the journal NEJM Evidence.

“I was not entirely surprised because infants in Israel are exposed to peanuts very early and allergy does not appear to emerge in adolescence or adults. This suggests the protection is long-term,” Gideon Lack, professor of pediatric allergy at King’s College London and an author of the study, said in an email.

“Peanut allergy develops very early in most children between six and 12 months of life. If you want to prevent a disease this needs to be done before the disease develops,” Lack said of exposing children to peanuts. “This biological phenomenon is based on an immunological principle known as oral tolerance induction. We have known for many decades that young mice or other experimental animals who are fed foods such as egg or milk or peanut cannot develop these allergies later.”

Starting in 2000, the American Academy of Pediatrics recommended delaying the introduction of peanuts until 3 years, but it ended that recommendation in 2008.

About a decade later, in 2019, the AAP updated its guidance to say that delaying the introduction of allergenic foods doesn’t prevent disease and that “there is now evidence that early introduction of peanuts may prevent peanut allergy.”

Food allergies have become a growing public health concern in the United States, and peanut allergy is estimated to affect about 2% of children in the United States, or nearly 1.5 million people younger than 18. Peanuts are among the food types that can cause the most serious allergic reactions, including the risk of the life-threatening reaction anaphylaxis.

“Today’s findings should reinforce parents’ and caregivers’ confidence that feeding their young children peanut products beginning in infancy according to established guidelines can provide lasting protection from peanut allergy,” Dr. Jeanne Marrazzo, director of the US National Institute of Allergy and Infectious Diseases, said in a news release Tuesday. “If widely implemented, this safe, simple strategy could prevent tens of thousands of cases of peanut allergy among the 3.6 million children born in the United States each year.”

The new study, called the LEAP-Trio trial, included data on children in the United Kingdom who participated as babies in a peanut allergy study called the LEAP trial.

That previous study included infants with eczema and egg allergy who were followed through age 5, and it found that at that age, the prevalence of peanut allergy was about 17% in the group of children who avoided peanuts, compared with about 3% in the group that ate peanut products, representing an 81% relative reduction in peanut allergy.

The LEAP-Trio trial set out to examine whether that reduced risk of peanut allergy would last into adolescence.

About 500 children were assessed again for the LEAP-Trio trial, which looked at the rate of peanut allergy at around age 12.

At that age, peanut allergy remained “significantly more prevalent” among the children who originally avoided peanuts, with about 15% having a peanut allergy. Among those who originally consumed peanuts, about 4% had a peanut allergy, the researchers found. They wrote that represents “a 71% reduction in the prevalence of peanut allergy at the LEAP-Trio time point.”

But overall, when children started to consume peanuts in infancy and continued to around age 5, this appeared to provide “lasting tolerance” to peanuts into adolescence, according to the researchers, based in the United Kingdom and the United States.

The new findings are “a great reassurance” that not only did early introduction of peanuts reduce peanut allergies from developing, but the protection lasted until adolescence even when children stopped eating peanuts consistently after age 5, Dr. Purvi Parikh, an allergist and immunologist at NYU Langone in New York and a spokesperson for the Allergy & Asthma Network, who was not involved in the new research, said in an email Tuesday.

“So ideally if there’s no other risk factors we should continue to introduce these allergens early at 4-6 months and continue them consistently until age 5 but after that we don’t need to be as consistent,” Parikh said.

She added that introducing peanuts for children at low risk for allergies can be done around 4 to 6 months old under the guidance of a pediatrician, but children with severe eczema and egg allergy should see an allergist before early introduction.

“Since babies cannot have solids yet it is recommended for it to be a thin consistency similar to breast milk or formula and can be mixed into it to avoid any choking and can start with a small amount and slowly increase as tolerated every 3-4 days,” Parikh said.

When introducing peanuts into an infant’s diet, it’s recommended to use smooth peanut butter mixed into a puree and avoid chunks of peanuts that could pose choking hazards.

“It can generally be said ‘the sooner the better’ for parents, especially in babies with eczema,” Lack said, adding that babies with eczema are at much higher risk of developing food allergies and develop these allergies much earlier in the first year of life.

“However, the child needs to be developmentally and neurologically ready to eat solid foods and be able to coordinate chewing and swallowing without a risk of choking. Most babies will be able to start weaning between four and six months of age but each baby is an individual and needs to be assessed individually,” he said. “Also, the foods should be given as a soft puree to facilitate swallowing and reduce the risk of choking. We do not recommend introducing solids before three months of age.”

The finding that early peanut introduction induces tolerance has been supported by previous studies too, but introducing your child to peanuts should be a shared decision with your pediatrician, according to Dr. Daniel DiGiacomo, a pediatric immunologist at K. Hovnanian Children’s Hospital at Jersey Shore University Medical Center in Neptune, New Jersey, who was not involved in the new study.

“The current expert opinion is to utilize a shared-decision making approach for food introduction once the infant is developmentally ready, and has tolerated a couple of other complementary foods without issue,” DiGiacomo said in an email Tuesday.

“I usually start off slowly introducing a pea sized amount, doubling the amount every day until you get to an age appropriate serving size (or at least 2 teaspoons). Then continue this in the diet several times per week,” he said. “I typically have the family mix the nut butter in a tolerated puree to the correct consistency, they can also dissolve peanut puffs (if doing peanut) in water, or make a peanut sauce out of powdered peanut butter or peanut flour. Again, we review the proper consistency and start slow with instructions to stop and contact your allergist if there are any concerns.”