As a specialist in food allergy, one of the frequent questions I get from parents of children with newly-diagnosed allergies is: “Is there anything that can be done to prevent food allergies?” Until recently, the universal answer was nothing at all.

Peanut allergy is the single most common food allergy in school-age children. Prevention can potentially make it one of the rarest food allergies. The ability to actively prevent the development of an allergy — or for that matter, any disorder of the immune system — is unprecedented in the history of medicine.

[See: 10 Concerns Parents Have About Their Kids’ Health.]

We now know that introducing foods early in life, when babies are only a few months old, can prevent the development of peanut allergies in many high-risk children. Unlike those with milk and egg allergies, the clear majority of peanut-allergic children are going to remain allergic for life to a nutritious food that’s baked into the American diet.

Food allergy prevention is a ground-breaking discovery in the history of food allergy research. This finding, involving years of research and hundreds of families, followed a very simple observation: Peanut allergy is rare in Israel, but very common in Jewish children growing up in the United Kingdom. The team of George du Toit and Gideon Lack discovered that Israeli babies routinely ate a finger food called Bamba, which is made of corn and peanut. This led to the hypothesis that exposing babies to peanuts in infancy can prevent peanut allergy.

To prove this hypothesis, they studied children at high risk of developing a peanut allergy. Over 800 babies with either severe eczema or egg allergy (one of the common food allergies of infancy) were screened for a peanut allergy. Even at this young age, 1 in 10 babies likely had a peanut allergy. One in 8 babies tested slightly positive for peanut sensitivity — but did not actually have a peanut allergy. The rest tested negative. Half of the infants were assigned to a group where the parents were told to feed their children peanut, and the other half to a group where the parents were told not to feed their children peanut starting as early as 4 months of age.

[See: 10 Healthy Meals You Can Make in 10 Minutes.]

Among the high-risk babies who tested slightly positive and were kept away from peanut, 35 percent — 1 in 3 babies — went on develop full blown anaphylactic food allergies. In this group, 10 percent of the children who were assigned to eat peanut developed peanut allergy. Even among the babies who tested negative, staying away from peanut led to a 14 percent chance of developing an allergy. When fed peanut, less than 2 percent developed a food allergy. This approach of early introduction of peanut may not prevent every baby from developing a peanut allergy. However, it’s a safe, effective method backed by high-quality research.

This landmark study led to the rapid alteration of guidelines for pediatricians, allergists and dermatologists, and radically changed what we recommend to parents of babies with severe eczema or other food allergies. All these children should be screened for the presence of peanut allergy. If the test is slightly positive or negative, the babies qualify for early introduction of peanut to prevent the development of peanut allergy. These children may need to eat peanut for the first time in a doctor’s office — a process called a food challenge.

Several unanswered questions remain. Does this apply to every food? Does introducing peanut prevent any other food allergies? Can other allergies be prevented using a similar procedure?

When you consider the impact of food allergies on a child’s life, one or two visits to a doctor’s office and feeding the child peanut butter is minimal effort. Recognizing how difficult it can be for parents of infants to be bring babies to the doctor’s office, we attempt to complete the skin test — and if applicable, food challenges for peanut — in a single visit.

[See: Top Reasons Children End Up in the Hospital.]

Why does this work? We truly don’t know. What we do know is that in the mother’s womb, our immune system is learning to recognize our “self” and understanding what is harmless. This process continues to some extent soon after birth, but it’s a rapidly closing window. We also know that the default response of the immune system, to food present in the gut, is to consider it harmless. However, in allergy-prone children, this process goes awry for some foods. Perhaps introducing peanut early in some children who are prone to developing food allergy provides one last chance to convince the immune system that a peanut is innocuous.

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How to Prevent Your Child From Developing a Peanut Allergy originally appeared on usnews.com