Can Infant Exposure to Peanuts Reduce Allergies Later?
By John Leung, MD
With my first child I was told to hold off on introducing peanut butter until he turned 1. I recently read a story that the National Institute of Allergies and Infectious Diseases recommends babies be exposed much younger, that trying it earlier could reduce allergic reactions later. Is this true?
Yes, it is true. A recent landmark clinical trial published in New England Journal of Medicine and other recent data suggest early introduction of peanuts in infancy reduces the risk of peanut allergy development later in life. More recently, a guideline has been published to provide practical recommendations on how, when, and where to introduce peanuts safely. The guideline suggests grouping infants into three categories when considering how, when, and where to try peanuts for the first time:
Category 1: Infants without eczema or any food allergy
Category 2: Infants with mild to moderate eczema
Category 3: Infants who have egg allergy and/or severe eczema
Infants in Category 1 are at lowest risk of developing a peanut allergy, and there is no concern of introducing peanuts with other solid foods at home. No specific timeframe has been recommended.
Infants in Category 2 can safely have peanuts introduced at home around 6 months of age to decrease the risk of developing peanut allergy.
Infants in Category 3 are at highest risk of developing a peanut allergy later in life, but they will also benefit the most from early introduction of peanuts at 4 to 6 months old. A simple blood test, known as peanut specific IgE level (peanut sIgE) or a skin prick test (SPT), are used to further determine the risk of reactions. While peanut sIgE measurement can be done at a pediatrician’s office, SPT are usually performed only by allergists.
The results of the peanut sIgE should help your child’s doctor recommend whether peanut introduction can safely be done at home without a doctor’s supervision, or if a referral to an allergist is warranted before introducing peanuts. The allergist will obtain a SPT with peanut extract. The larger the wheal (red, swollen mark) size, the higher the risk of reaction:
If the size of the wheal is 0-2mm, peanuts can be safely introduced at home.
If the wheal size is 3-7mm, peanuts should be introduced at the allergist’s office, as the risk of a reaction is moderate.
If the wheal is 8 mm larger than saline control, the infants are probably allergic to peanuts and should continue to work with the allergist for management.
John Leung, MD is a board-certified gastroenterologist and allergist; co-director of the Food Allergy Center at Floating Hospital of Tufts Medical Center; and a clinical professor at the Friedman School of Nutrition Science and Policy at Tufts University, Boston.