Update on Peanut Allergy

Our understanding of healthcare is constantly evolving, but it’s not every day that a new discovery truly changes our day-to-day practice of medicine. The early introduction of peanut-containing foods in infancy may actually prevent peanut allergy.

Our understanding of healthcare is constantly evolving, but it’s not every day that a new discovery truly changes our day-to-day practice of medicine.  But this is exactly what happened in the field of pediatric food allergy this past month.  In a nutshell (pun intended): the early introduction of peanut-containing foods in infancy may actually prevent peanut allergy.

Peanut allergy is the leading cause of fatal and near-fatal food allergic reactions in the United States, and the prevalence of peanut allergy in Western countries has doubled over the past 10 years.  Peanut allergy usually begins early in life and persists through adulthood.  For many years, experts thought the best way to reduce or prevent peanut allergy was to completely avoid peanut-containing products for the first years of life.  These recommendations had very little impact on the problem of peanut allergy, however, and have since fallen by the wayside.

About a decade ago, researchers in the United Kingdom noticed an interesting phenomenon: peanut allergy in Jewish children living in the UK was about 10 times more common than it was in Jewish children living in Israel.  Since ancestry (and therefore genetics) were presumably similar, what were the environmental factors contributing to this large difference?  The answer was a major difference in the children’s diets.  Children in the UK rarely ate peanut products in the first year or so of life, but the Israeli children commonly ate a peanut butter containing puff snack called Bamba.  This observation spurred a large 5-year clinical trial of over 600 babies, called the Learning Early About Peanut Allergy (LEAP) trial.  The babies studied were all considered to be at high risk of developing peanut allergy due to their history of severe eczema, egg allergy, or both.  One group was given Bamba (or peanut butter) to eat, the other group was told to avoid peanut-containing foods.  This was continued until the children were 5 years old.  The results of the LEAP trial were published about a year ago, and the news was amazing.  Not only was early introduction of peanut-containing foods to these high-risk infants safe, but it resulted in an 81% reduction of developing peanut allergy.

An expert panel convened last summer to review the results of the LEAP trial and develop clinical guidelines to address the prevention of peanut allergy.  This consensus from the National Institute of Allergy and Infectious Diseases was published last month and endorsed by the American Academy of Pediatrics.  The guidelines divide babies into 3 groups based on risk factors: 1) those with severe eczema and/or egg allergy; 2) those with mild to moderate eczema; and 3) those who don’t have any history of eczema or food allergies.

The first group of infants (those with severe eczema and/or egg allergy) are considered “high risk,” and testing for peanut allergy should be strongly considered first.  Testing may consist of bloodwork, skin prick testing, or both.  Your doctor may also recommend additional evaluation by an allergy specialist.  Talk to your child’s doctor first about his/her particular history and risk factors.  Ideally, peanut-containing products should be introduced to these high-risk babies as early as 4 to 6 months of age.  However, other low-risk solid foods should be tried first to ensure your infant is developmentally ready.  Depending on the scenario and results of allergy testing, it may be prudent to introduce peanut products in a supervised setting (e.g., in the doctor’s office).

The second group of babies with mild to moderate eczema may also have increased risk of developing peanut allergy.  However, initial allergy testing is not routinely recommended.  Peanut-containing products should be introduced to these babies around 6 months of age, after other low-risk foods have been tolerated and in accordance with family preferences.  Most of these infants can be introduced to peanut at home.

Infants without eczema or other food allergies are not at increased risk for developing peanut allergy.  They may start eating peanut-containing products and other highly allergenic foods freely after a few other solid foods have been introduced and tolerated without difficulties.  For these babies, the early introduction of peanut-containing foods is not as crucial as in the other two groups.  Of course, families’ preferences and cultural practices should always be considered.

General recommendations are for parents to first introduce “low allergy risk foods” to their infants starting between 4 and 6 months of age, if babies are developmentally ready.  The AAP recommends breastfeeding as the sole source of nutrition for infants until this time.  These low risk foods are most of the pureed veggies and fruits.  Babies should be given one new food at a time, waiting at least 2 to 3 days in between each new food.  After each new food, any potential allergy symptoms such as diarrhea, rash, vomiting, or difficulty breathing should be reported to your child’s doctor immediately.  If your baby is low-risk for food allergies, and tolerating her first few foods without difficulties, you can then start to introduce more highly allergenic foods.  These higher risk foods include milk, egg, soy, wheat, peanut, tree nuts, fish, and shellfish.  It’s important to remember that all foods should be in age-appropriate forms and textures.  For example, whole cow’s milk is not recommended until 1 year of age, but processed dairy products such as yogurt and cottage cheese can be introduced per the above recommendations.  Whole peanuts (and tree nuts) themselves are choking hazards and should never be fed to babies.  Peanuts can be introduced to infants by thinning-out peanut butter or dissolving peanut butter puffs with water, breastmilk, or formula.  If your baby has tolerated other low-risk purees (fruits, veggies, yogurt), peanut butter could also be thinned and mixed with these.

It remains to be seen what impact these new guidelines will ultimately have on the reduction and prevention of peanut allergy in the US.  The data is quite convincing, however, and has certainly changed the way I counsel parents.  Please discuss your child’s individual situation with your doctor before peanuts or any other highly allergenic foods are introduced.

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