Childhood Food Allergy Questions Answered by Chief Allergist Katie Marks-Cogan, M.D.

Have questions on food allergies? We’ve got answers! Our Chief Allergist and Board Certified Allergist Katie Marks-Cogan, M.D. answers your most commonly asked questions on food allergies.


Childhood Food Allergies

What are the top allergens parents should be aware of?

Eight foods/food groups are responsible for causing most food allergies: milk, eggs, peanuts, tree nuts, wheat, soy, fish and shellfish. Sesame has just been added as the ninth major food allergen. However for children, peanut, egg and milk represent the most common childhood food allergens to cause allergic reactions.

Why are food allergies on the rise?

With 1 in 13 children suffering from a food allergy, there are many theories for this troubling trend, including:

  • Food Allergen Avoidance - The previous recommendation was that parents avoid allergenic foods for their child’s first year, which is now considered a risk factor for food allergy development.
  • Vitamin D Insufficiency - There is evidence that suggests that infants with low Vitamin D levels are more likely to develop food allergies.
  • The Hygiene Hypothesis - Lack of exposure to the right germs and/or allergens can skew a child’s immune system towards the development of a food allergy.
  • Dual Allergen Exposure Hypothesis - Multiple studies (such as this study) suggests that exposure to allergens through the skin can actually promote allergy, while early oral exposure can promote tolerance.

What factors contribute to my child’s risk for developing food allergies?

There are many factors that determine your child's risk for food allergies including family history and gender but eczema or atopic dermatitis is the most important one to consider. This is primarily because research shows that infants with eczema are at the highest risk for developing food allergies. In fact, up to 67% of infants with severe eczema and 25% of infants with mild eczema will develop a food allergy.


Introducing Allergens: Recent Research and How To Introduce

Is there research to show the benefit of introducing allergens vs avoiding the common ones?

In the landmark Learning Early About Peanut (LEAP) study on early allergen introduction, children were randomly divided into two equal groups: the first group was fed peanut regularly and the second group avoided peanut completely until age 5. Comparing the two groups, those infants consuming peanuts were over 80% more likely to not have a peanut allergy at 60 months of age. Therefore, the study revealed that early, consistent peanut introduction significantly reduces peanut allergy risk whereas avoidance was associated with an increased risk of peanut allergy. These findings were further reinforced by similar findings from two other landmark studies on early allergen introduction, the Enquiring about Tolerance (EAT) Study and the Two-step egg introduction for prevention of egg allergy in high-risk infants with eczema (PETIT) Study.

What are the best tactics for introducing potential allergens and at what age?

In addition to the latest United States Department of Agriculture (USDA) guidelines on the introduction of allergenic foods, the American Academy of Allergy, Asthma, and Immunology (AAAAI) and American Academy of Pediatrics (AAP) suggest that parents begin introducing allergens to their baby as early as 4 months. Starting as early as 4-6 months will align with an infant’s critical immune window. This window gives your infant the best opportunity to develop a positive response to new foods. This is especially important for infants with eczema, who are at an increased risk for developing food allergies.

Parents can follow the The National Institute of Allergy and Infectious Diseases (NIAID) Addendum Guidelines, which offers recipes for introducing peanut to infants.

How much of the potential allergen should be given and for how long to be confident there is no issue?

It’s a common misconception that introducing allergenic foods to your infant once or a few times is effective. Unfortunately, it’s not that simple. Oral tolerance requires repeated exposure. In fact, there is no evidence that introducing allergenic foods only once is effective. In the LEAP study, infants were fed peanuts consistently for up to 5 years of age. I would recommend that parents consistently feed their infants allergens multiple times a week for several months.



Introducing Allergens: Safety and When to Introduce

Is there any way to tell if a baby may have a sensitivity before they start with food?

While I know many parents are anxious about feeding their baby potential allergy-causing foods, it’s important for parents to know that in the three landmark clinical trials (including the LEAP study) on early introduction with over 2,000 babies as early as 4 months, there weren’t any cases of a severe reaction or hospitalizations. In addition, newer research suggests that allergic reactions get more severe as your baby gets older, so starting as early as possible is the safest way to feed allergens to your baby. That’s why it’s so important to start early. And, if your baby is not yet ready for solids (as many aren't at 4 months), Ready. Set. Food! packets can be added to a bottle with breast milk or formula.

What are signs that there may be an issue?

In babies and young children, hives (red raised bumps) and vomiting are the most common symptoms of an allergic reaction. Other mild to moderate symptoms of a food allergic reaction include swelling of the face, lips, and eyes. However, there are many different symptoms that your child can experience. A food allergy reaction could affect the skin, eyes, mouth, respiratory system, gastrointestinal system, or cardiovascular system.

Most importantly, be mindful that a mild to moderate reaction can sometimes quickly develop into anaphylaxis. This is true even for someone who has never had a food allergic reaction, or who has only had mild to moderate reactions previously. When the symptoms of a food allergic reaction are severe, and involve more than one organ system, the reaction is classified as anaphylaxis. And anaphylaxis can be life-threatening.

If my baby is older than 6 months, is it too late to introduce allergens?

Although earlier exposure is favorable, it’s important to introduce as early as you can. Many parents worry that their baby will have a reaction, but research has shown that allergic reactions are much less severe in younger infants than in toddlers and older children, so parents should not delay. Anaphylaxis, or severe allergic reactions, tend to happen more as children get older.


Breastfeeding, Eczema and Food Allergies

Do I still need to introduce allergens if I ate peanut, egg, and milk while breastfeeding and pregnant?

A lot of parents tell me they think breastfeeding is enough. Unfortunately, this is not true. While breastfeeding has many benefits, current research is inconclusive on its role in food allergy development. National medical guidelines recommend that even moms who are exclusively breastfeeding introduce allergens starting at 4-6 months.

What do you recommend for parents of babies with eczema?

Up to 67% of babies with eczema will develop food allergies, so early allergen introduction is particularly important for this high-risk group. National medical organizations such as the American Academy of Pediatrics and the National Institutes of Health recommend that parents of babies with eczema begin allergen introduction at 4 months, and it is extremely important to not delay introduction in this group.


About Katie Marks-Cogan, M.D.: Dr. Marks-Cogan is board certified in Allergy/Immunology and Internal Medicine, and treats both pediatric and adult patients. Originally from Cleveland, Ohio, she received her M.D. with honors from the University of Maryland School of Medicine. She then completed her residency in Internal Medicine at Northwestern and fellowship in Allergy/Immunology at the prestigious University of Pennsylvania and Children's Hospital of Philadelphia (CHOP). After finishing training, she moved to Southern California where she works in private practice and is the owner of Clear Allergy. She is also Chief Allergist and a member of the scientific advisory board for Ready. Set. Food! She has numerous media appearances and has authored many articles pertaining to topics in the field of allergy. She currently resides in Los Angeles with her husband, 6-year-old son, and 3-year-old daughter where she enjoys hiking, building LEGO castles with her kids, and cooking with her family.

Introduce Allergens Safely and Easily with Ready. Set. Food!

All health-related content on this website is for informational purposes only and does not create a doctor-patient relationship. Always seek the advice of your own pediatrician in connection with any questions regarding your baby’s health.

These statements have not been evaluated by the Food and Drug Administration. Products are not intended to diagnose, treat, cure or prevent any disease.  If your infant has severe eczema, check with your infant’s healthcare provider before feeding foods containing ground peanuts.