Early Allergen Introduction Q&A with Board Certified Pediatrician Dr. Leila Yoonessi

Pediatric Pulmonlogist and Pediatrician Leila Yoonessi, M.D. answers your most commonly asked questions about early allergen introduction and discusses why she recommends Ready. Set. Food! to parents and her patients. Ready. Set. Food! is proud to have the support of 1,000+ doctors who recommend our evidence-based approach to early allergen introduction.


Childhood food allergies seem to have increased dramatically since my childhood, why is that?

I’ve seen the rise in food allergies firsthand in my practice with many of my pediatric patients suffering from one or multiple food allergies. There are many theories as to why 1 in 12 children suffer from a food allergy today, including:

  • Hygiene Hypothesis - The lack of microbial exposure or in other words, lack of exposure to germs and/or allergens in childhood can weaken the immune system towards the development of allergy, with many studies supporting this theory. Therefore, by exposing your child to germs and/or allergens, that exposure can strengthen your child’s immune system and in turn, can help fight off the development of illnesses and food allergies.
  • Vitamin D Deficiency - There is research that suggests that infants with low vitamin D levels may be more likely to have egg or peanut allergy compared to infants with normal vitamin D levels.
  • Delayed Exposure - The landmark LEAP study not only demonstrated that introducing allergens early is vital but also that delaying exposure to allergenic foods can put your baby at a greater risk for developing allergies to those foods.

What do you tell parents of babies with eczema?

All babies are at risk for developing food allergies, as over 50% of children who suffer from one or multiple food allergies have no family history of food allergies. However, there are some important risk factors that can put your child at a greater risk for developing food allergies, including eczema.

  • Eczema: Where there are other risk factors for developing a food allergy, eczema is the most important risk factor to consider. Up to 67% of infants with severe eczema and 25% of infants with mild eczema will develop a food allergy. That’s why new guidelines from the AAP and NIH on early allergen introduction are specifically focused on infants with eczema as these infants need early allergen introduction the most.
  • Family history: Research suggests that if you have a sibling with a food allergy, your risk of developing one is 13%, compared to 8% in the general population (or 1 in 12 children).
  • Delayed Exposure: Delaying the introduction of allergenic foods into an infant’s diet can increase their risk of food allergies. Research has shown that introducing allergenic foods like egg and peanut into an infant’s diet around 4 months of age can significantly decrease their risk of developing food allergy.

If my baby or toddler is allergic to something, what type of reaction should I be looking for?

It’s important to note that in the three landmark clinical trials (LEAP, EAT, PETIT) on early allergen introduction with over 2,000 infants who participated in those studies, there were zero cases of severe allergic reactions. This underscores the inherent safety of early allergen introduction. In addition, there is new research that indicates that if you introduce allergens to your infant (under a year of age), there is no risk for anaphylaxis based on survey data collected from all the oral food challenges that took place at the Children’s Hospital of Philadelphia and Vanderbilt University between September 2016 and February 2019.

However, parents should be still aware of the signs of an allergic reaction, which in most babies will appear as hives and/or vomiting. Other mild to moderate symptoms include swelling of the face, lips, and eyes.

Learn more about the signs of an allergic reaction from the American Academy of Pediatrics:

Why do you recommend Ready. Set. Food!?

There are new USDA Guidelines for Infants and Children that recommend introducing allergens such as peanut and egg starting at 4 months of age. Since many 4 month old babies are not developmentally ready for solid foods at 4 months of age, Ready. Set. Food! allows families to follow the new research and guidelines on food allergies by introducing allergenic foods in a bottle so that all babies can benefit from early allergen introduction. It’s important that parents follow these new guidelines because if every parent introduced allergens early and often, there would be 200,000 fewer cases of food allergies in children. That’s a significant difference in the quality of life and health for thousands of children and that’s one of the reasons I recommend Ready. Set. Food! at every 4 month well visit.


About Dr. Lelia Yoonessi: Dr. Leila Yoonessi is a pediatric pulmonologist practicing in Long Beach, CA. She practices pediatric pulmonology and general pediatrics. Dr. Yoonessi holds a BA in psychobiology with a minor in religious studies from Occidental College. She graduated cum laude and was awarded a psychobiology departmental award for her academic achievements. She then studied at the University of Southern California where she earned Master’s in Public Health with a concentration in health care promotion. She went on to complete her medical degree at New York Medical College. She relocated to California to rejoin her family where she completed her pediatric residency at Los Angeles County University Southern California. She is currently a board certified pediatrician who has several research interests. Publications include Progression and Prognostic Indicators of Bronchial and Alveolar Disease in Children with Sickle Cell Disease, and Environmental factors contributing to lung function and growth velocity decline in Sickle Cell Disease. Above all, she remains committed to patient advocacy, research, integrative work, medicine, preventive medicine, holistic health, and non-profit work. Dr Yoonessi enjoys horseback riding, hiking with her 2 Shiba Inus and camping for fun.

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.