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Peanut Allergies in Babies: Early Introduction and Breastfeeding Insights

TL;DR: Introduce peanuts to your little one as soon as they have a solid foundation of safe foods directly! For parents eager to learn how to start solids safely and introduce important allergens like peanuts, our Successfully Start Solids Masterclass is for you!

Today, we're diving into a nutty topic that's on a lot of your minds: peanut allergies in our little ones. We’ve been keeping an eye on the latest research and wanted to share some enlightening insights that could help ease your worries and guide your decisions.

Person pulling peanuts up from the ground by their stem

Peanuts, despite commonly being grouped with nuts, are actually legumes, similar to beans and lentils. They grow underground, where their delicate shells house the edible seeds we enjoy as snacks. Unlike tree nuts, peanuts develop inside a soft, textured pod that matures beneath the soil surface, which makes them quite unique in the world of seeds and nuts.

Two key proteins found in peanuts, Ara h 2 and Ara h 6, are particularly noteworthy because they are major allergens responsible for many peanut allergy reactions. These proteins are part of the peanut’s defense mechanism, helping it survive in its growing environment, but in sensitive individuals, they can trigger immune responses that range from mild to severe [1]. Understanding these proteins is crucial for managing and researching peanut allergies, as they are central to how allergists diagnose and treat this common food allergy.

Peanuts are not only a staple in cuisines worldwide but also a source of high-quality plant-based protein, making them a nutritious (and delicious!) addition to many diets. However, because of the highly allergenic potential of proteins like Ara h 2 and Ara h 6, introducing peanuts to infants requires careful consideration.

What’s the Deal with Peanuts and Breast Milk?

Did you know that when you munch on peanuts, the proteins (hello again, Ara h 2 and Ara h 6!) can pop up in breast milk? That's right, they often make their debut within 1 to 3 hours after you eat them and then are shown to steadily decline in concentration from there [2]. Most individuals clear these proteins within 8 hours while a few may take up to a full day! This is super important because it means human milk can be the first gentle introduction to these allergens for your baby.

Fun Fact: The fastest researchers have seen peanut transfer from ingestion to the breast is 10 minutes [3]!

Woman breastfeeding cute infant

Why is it "gentle"? When we enjoy a snack like peanuts, not only do we get to savor the taste, but our body gets to work breaking down the proteins, including those famous allergens Ara h 2 and Ara h 6. This process doesn't stop at digestion. Some of these proteins, now in smaller, less complex forms, make their way into our circulatory system and can be transferred into breast milk [4]. It is important to note that some researchers have found Ara h 1 and Ara h 2 intact, or not broken down, inside breast milk as well [5]! This transfer is a perfectly natural biological function that happens in everyone, not just those with allergies. By the time these proteins reach the baby, they've been partially broken down and/or diluted, making this early exposure a soft start in recognizing and handling potential allergens [6]. It's nature's way of easing our little ones into the world of foods they’ll soon enjoy!

The Scoop on Early Peanut Introduction

Here’s the kicker: introducing peanut-containing foods to your baby’s diet between 6 to 11 months might significantly cut down the chances of them developing a peanut allergy [7]. The science shows that the combination of getting these proteins through breast milk and directly through foods can help train their little immune systems to tolerate peanuts rather than react to them [8].

Research-backed Tips

  1. Through You First: If you're breastfeeding and peanuts are a part of your diet, your breast milk will likely carry small traces of peanut proteins [9]. This can be a natural first step toward introducing your baby to peanuts.

  2. Early and Often Introduction: When you start introducing solid foods, you can include small amounts of peanut-containing foods as early as 6 months, assuming they’ve handled other solids just fine. Keep an eye out for any reactions, and always have a chat with your provider first if you have questions. Learn more about Early and Often Intros - like what classifies as "often" and how much protein should my kiddo be getting - in our blog here!

  3. Dual Exposure Works Wonders: Studies have shown that when both you and your baby are exposed to peanut proteins—through your diet/breast milk and their snacks—it increases the probability of lifelong tolerance, which is great news for preventing allergies!

Recognizing Symptoms of Peanut Allergies in Babies

Family having breakfast of orange juice and peanut butter toast

When introducing peanuts to your baby, whether through breast milk or directly, it’s essential to recognize the signs of a possible allergic reaction. Peanut allergies can manifest in various ways, and understanding these can help you quickly identify and manage any adverse responses. If your baby shows any signs of a severe reaction, such as difficulty breathing or loss of consciousness, seek immediate medical attention.

Types of Reactions: IgE vs. Non-IgE

  • IgE-Mediated Allergies: These reactions happen when the immune system overproduces antibodies called immunoglobulin E (IgE) in response to peanut proteins. Symptoms can be acute and severe, including hives, swelling, difficulty breathing, wheezing, and in severe cases, anaphylaxis—a rapid, potentially life-threatening condition.

  • Non-IgE-Mediated Allergies: These involve parts of the immune system other than IgE antibodies and commonly result in symptoms such as colic, reflux, vomiting, eczema, diarrhea, constipation, blood/mucus in stool, and failure to thrive [10].

Timing of Reactions: Acute vs. Chronic

  • Acute Reactions: Quick to manifest, these are common with IgE-mediated allergies where symptoms occur immediately or up to a few hours after ingestion. Non-IgE symptoms that occur in the upper GI system (like vomiting or reflux) or on the skin (like eczema) can also be acute. Acute reactions are often ones which resolve quickly - within hours to days - compared to its chronic counterpart [11].

  • Chronic Reactions: Seen more often with Non-IgE-mediated symptoms occurring in the lower GI system and sometimes the skin, these are triggered several hours after ingestion and can take up to 2 days to see the full peak response. Symptoms might be less dramatic but persist longer because the healing process for something like blood in stool can take more time than recovering from an episode of vomiting [11].

When Peanut Introduction Doesn't Go as Planned

Introducing peanuts to your baby, whether through breast milk or directly, is generally part of a strategic plan to help ensure tolerance. However, if your baby already shows signs of a peanut allergy, or if symptoms arise at any point, it's crucial to handle the situation with care. The primary goal of any introduction, including methods like Oral Immunotherapy (OIT), is to avoid triggering an allergic reaction. Remember, the process should be symptom-free. If your baby already has an IgE mediated allergy to peanuts, you can learn more about OIT and similar tolerance programs here!

If consuming peanuts yourself seems to affect your baby, or if direct introduction leads to symptoms, it's important to stop immediately. This isn't a scenario where the old saying "just a little won’t hurt" applies — advice you might hear from well-meaning relatives like Aunt Mable. Instead, pausing the introduction and consulting with a professional is essential. Expert guidance will ensure that any future steps you take are safe and tailored to your baby's specific health needs, helping manage the allergy with informed care. This includes making sure that we are not unnecessarily avoiding peanuts after confusing symptoms from something like an illness with that of our peanut trial. We only want to avoid peanuts when we know it causes reactivity [12].

Smiling child with peanut butter on their face

Keeping It Real

Navigating food allergies can feel like a maze, but here at Free to Feed, we’re all about turning complicated science into helpful, everyday tips. Whether it’s figuring out the best time to introduce allergenic foods or understanding how your diet affects your baby, we’re here every step of the way.

We’re Here to Help

If you’re ever unsure or need a little guidance, don’t hesitate to reach out. Our community is full of supportive parents and experts who’ve been exactly where you are now. Let’s keep the conversation going and make food discovery with your baby a joyful journey! Learn more about our consultation services and see if your insurance will cover the costs here.


  1. Abrams, Elissa M., Edmond S. Chan, and Scott Sicherer. "Peanut allergy: new advances and ongoing controversies." Pediatrics 145.5 (2020).

  2. Schocker, Frauke, et al. "Prospective investigation on the transfer of Ara h 2, the most potent peanut allergen, in human breast milk." Pediatric Allergy and Immunology 27.4 (2016): 348-355.

  3. Bernard, Herve, et al. "Peanut allergens are rapidly transferred in human breast milk and can prevent sensitization in mice." Allergy 69.7 (2014): 888-897.

  4. Vadas, Peter, et al. "Detection of peanut allergens in breast milk of lactating women." Jama 285.13 (2001): 1746-1748.

  5. Zhu, Jing, et al. "Discovery and quantification of nonhuman proteins in human milk." Journal of proteome research 18.1 (2018): 225-238.

  6. Schocker, Frauke, and Uta Jappe. "Breastfeeding: maternally transferred allergens in breast milk: protective or sensitizing?." Molecular Nutrition & Food Research 66.15 (2022): 2200066.

  7. Du Toit, George, et al. "Randomized trial of peanut consumption in infants at risk for peanut allergy." New England Journal of Medicine 372.9 (2015): 803-813.

  8. Pitt, Tracy J., et al. "Reduced risk of peanut sensitization following exposure through breast-feeding and early peanut introduction." Journal of Allergy and Clinical Immunology 141.2 (2018): 620-625.

  9. Schocker, Frauke, et al. "Detection of the peanut allergens Ara h 2 and Ara h 6 in human breast milk: development of 2 sensitive and specific sandwich ELISA assays." International archives of allergy and immunology 174.1 (2017): 17-25.

  10. Labrosse, Roxane, François Graham, and Jean-Christoph Caubet. "Non-IgE-mediated gastrointestinal food allergies in children: an update." Nutrients 12.7 (2020): 2086.

  11. Sicherer, Scott H., et al. "Food allergy from infancy through adulthood." The Journal of Allergy and Clinical Immunology: In Practice 8.6 (2020): 1854-1864.

  12. Du Toit, George, et al. "Effect of avoidance on peanut allergy after early peanut consumption." New England Journal of Medicine 374.15 (2016): 1435-1443.


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