Food allergies, breastfeeding, and the latest AAP guidelines

Yvette Zhu
June 23, 2020

Eeek!!! Food Allergies and breastfeeding can get insanely overwhelming. First things first, if you see signs of an allergic reaction with your baby, talk to your pediatrician as soon as you can. For those not experiencing any issues with allergies and want to educate yourself to be informed, we wanted to demystify it for you! Hooray!

So what is an allergy?

Allergies occur when the immune system becomes overly sensitive to a usually harmless substance. The first time someone is exposed to the allergen, aka the substance that causes the immune system to overreact, they don’t usually experience a reaction. Over time, however, the immune system can learn to recognize the allergen and start making antibodies when exposed to that allergen. This is a process called sensitization. In terms of food allergies, there are eight major food allergens that account for about 90% of all food allergies in the U.S.. These include cow milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat, and soybean [1].

According to the American Academy of Pediatrics (AAP), babies with at least one first-degree relative, such as a parent or sibling with allergic diseases are at higher risk for developing allergies or atopic diseases.  Atopy is the genetic tendency to develop certain common allergic diseases, specifically when the immune system produces a type of antibody called immunoglobulin E (IgE). Atopic dermatitis, also known as eczema, is a common allergic condition in early childhood, appearing as skin inflammation, itchiness, redness, rough patches, and sometimes blisters [2]. Asthma is another common allergic mediated response in the airways with symptoms of fast breathing, shortness of breath, coughing, and wheezing (a whistling, squeaky sound when breathing) [3].

What does an allergic reaction look like?

An allergic reaction to food can show up in many different ways, but some common reactions in infants include rash, swelling, difficulty breathing, colic, vomiting, diarrhea, and bloody stools.  Most responses develop within an hour after ingestion, but the more sensitive to an allergen, the quicker the response time.  If there are any concerning signs please contact your pediatrician.

Ok, now what should I do?

On March 18, 2019, the American Academy of Pediatrics (AAP) published new guidelines and research findings on the role of nutrition in developing food allergies [1]. Here are some highlights of the study and answers to the questions you may have:

Can breastfeeding or maternal diets help prevent baby allergies?

As of now, there is no conclusive evidence to support that exclusive breastfeeding can help prevent baby allergies. However, exclusive breastfeeding for at least three to four months may be associated with lower risk of developing eczema in the first two years of life. There also isn’t conclusive evidence showing that excluding allergens such as peanuts, cow’s milk, and eggs from the mom’s diet can help prevent food allergies in babies.

What about hydrolyzed infant formulas?

When choosing infant formulas, you might see the word “protein hydrolysate,” or the label
“hydrolyzed formula.” This means that the proteins in the formula are either partially or completely broken down into smaller, more digestible pieces. These kinds of formulas are usually made for babies who don’t tolerate cow milk or soy-based proteins well. As of now, there has not been enough evidence suggesting that hydrolyzed formulas can help prevent food allergies or eczema.

When to introduce potential allergens like peanuts to the baby’s diet?

AAP recommends introducing allergens between 4-6 months of age.  The general consensus is not to introduce earlier than 4 months but also that there is no benefit of delaying after 6 months.  

For peanut proteins specifically, it is recommended to introduce as early as four to six months if the baby has a high risk for peanut allergy. For babies with low to moderate risk for peanut allergy, they can start consuming peanut protein within the first year of age. These recommendations were based on the Learning Early About Peanut Allergy (LEAP) study of over 600 infants at high risk for peanut allergy.  The study showed an 80% reduction in the allergy in children who ate peanut protein as early as four months of age versus children who avoided peanut protein until they were five years old [1, 4].


  1. Greer, Frank R., et al. “The Effects of Early Nutritional Interventions on the Development of Atopic Disease in Infants and Children: The Role of Maternal Dietary Restriction, Breastfeeding, Hydrolyzed Formulas, and Timing of Introduction of Allergenic Complementary Foods.” American Academy of Pediatrics, American Academy of Pediatrics, 1 Apr. 2019,
  2. Waldman, Andrea R., et al. “Atopic Dermatitis.” American Academy of Pediatrics, American Academy of Pediatrics, 1 Apr. 2018,
  3. “AAFA.” What Are Asthma Symptoms? |,
  4. Toit, George Du, et al. “Randomized Trial of Peanut Consumption in Infants at Risk for Peanut Allergy: NEJM.” New England Journal of Medicine, 26 Feb. 2015,