Expert Tips for Safely Introducing Common Food Allergens to Kids

Will eating peanut butter cause a peanut allergy? This question (and many others) are often top of mind when it’s time to transition baby from breast milk or formula to solid food. Thanks to mixed messages over the years, it’s easy for parents to wonder whether they should delay potential food allergens or introduce early and often, so we’re bringing in an expert to clear up any confusion. 

Even as a board-certified pediatric and adult allergist in private practice, Dr. Katie Marks-Cogan found it challenging and time consuming to introduce allergens to her own children consistently. When a friend reached out for help after his son was diagnosed with multiple food allergies, Marks-Cogan knew she wanted to reduce the risk of babies developing food allergies in the first place. Together with Daniel Zakowski and Dr. Andrew Leitner, Marks-Cogan co-founded Ready Set Food! to simplify allergy introduction for busy families (and picky eaters).

When to Introduce Common Allergy Foods

For Marks-Cogan, it all starts with prevention. Since there’s no cure for food allergies, she advocates for reducing the risk of developing one. “When it comes to introducing and maintaining allergens in a baby’s diet, earlier is safer,” she says, and recommends that parents talk to their pediatrician as early as the three-month visit so they can have a feeding plan in place when the time comes. “Waiting to introduce allergens not only increases the likelihood of a child having a food allergy, it also increases the likelihood of a more serious reaction.”

Peanut Allergy, Milk Allergy, and Egg Allergy: What the Studies Show

Recent studies—including over 20 clinical trials with nearly 14,000 subjects—have demonstrated that exposing babies to common food allergens early and consistently results in a reduction in food allergies. Two of the most well-known trials—Learning Early About Peanut Allergy (LEAP) and Enquiring About Tolerance (EAT)—found that the regular consumption of peanuts reduces peanut allergy risk. Recently, the authors of those 2015 and 2016 U.K. studies re-analyzed the data to better understand the infants most at risk for developing a peanut allergy and the best way to reduce peanut allergies across the board. “One of the most significant findings from this research was that the impact of early allergen introduction decreased as the age of introduction increased,” Marks-Cogan shares. “That means waiting longer to introduce peanuts makes it less likely to reduce the risk of a peanut allergy.” 

The early introduction of eggs has been studied globally in the EAT study, PreventADALL study (the Netherlands) and the PETIT study (Japan). “All of these studies have found the same thing: Introducing eggs at four to six months and then feeding eggs regularly is safe, even for babies with severe eczema, and prevents egg allergies,” Marks-Cogan notes. 

Clinical trials for milk are a bit more complicated because in the United States, you can’t assign some babies to drink formula and others to be breastfed. Still, Marks-Cogan says international trials have shown that “the early introduction of cow’s milk using an appropriate form factor can prevent milk allergies. In Japan, parents fed their babies 10 mL (about ⅓ oz) of cow’s milk formula each day starting at birth and found that it didn’t interfere with breastfeeding, and prevented cow’s milk allergies at six months. Another study found that babies who consistently consumed some amount of cow’s milk formula had much lower rates of cow’s milk allergy than those that had no exposure to dairy or had irregular exposure.” 

The big takeaway? Once you introduce an allergen, it’s important to stay consistent and offer it regularly.

How to Introduce Food Allergens to Kids 

Here are the most common foods that may cause an allergic reaction in babies.

• Cow’s milk 
• Eggs
• Peanuts
• Soy
• Wheat
• Tree nuts (such as walnuts, pistachios, pecans, etc.)
• Fish 
• Shellfish
• Sesame

If you’re wondering where to start, Marks-Cogan says that peanuts, eggs, and milk account for nearly 80 percent of all childhood food allergy reactions, so it’s best to begin there. 

Between the ages of four to six months might be the best window of opportunity to introduce allergens to your baby, but every situation is unique. Since not all babies are ready for solids at this time, one option is to use a mix-in supplement for bottles that provides the top three most common allergens at one time. For a DIY approach, parents can thin peanut butter with water, prepare soft scrambled eggs, or offer plain yogurt or cottage cheese.

When you’re ready to introduce food allergens the easy way, Ready Set Food! is here to help. Their purées support allergen introduction for babies 6+ months (and deliver protein without any added sugar), their puffs are made with 9 top allergens and have a melt-in-your-mouth texture that’s perfect for young eaters, and their bars are great for older kids and made with 8 top allergens:

• Organic Banana Blueberry Baby Food Purée
• Organic Apple Peach Cinnamon Baby Food Purée
• Organic Apple Banana Carrot Baby Food Purée
• Organic Peanut Butter Berry Puffs
• Organic Apple Cinnamon Puffs
• Organic Peanut Butter Puffs
• Organic Blueberry Banana Oat & Fruit Bars

Allergy Symptoms in Kids FAQ

Safety first! Review these common questions to help ensure a smooth start.

How do you know if your child is at risk for food allergies? 

All babies are at risk for food allergies, so early allergen introduction is important. In fact, most kids who develop food allergies don’t have a family history. There are some risk factors to look out for, including eczema, a common childhood rash, and existing food allergies that your pediatrician can help identify. Early allergen introduction can be done safely under a doctor’s supervision or direction, even for high-risk babies.

What are the signs of allergies in kids? 

Even with the all-clear from your doctor, be on the lookout early on for signs that might indicate your child is allergic to a certain food. Symptoms include hives, swelling of the lips or tongue, stomach upset, significant coughing, and breathing problems. In babies, the most common symptoms are hives and vomiting. As for the timing, Marks-Cogan says these symptoms usually occur within seconds to several minutes, and almost always within two hours. “A food allergy should not be confused with a food intolerance, which is an adverse health effect caused by foods and usually involves the digestive system. Symptoms of different food intolerances can include: diarrhea, gas, bloating, or a stomach ache.” 

What do you do if your child has an allergic reaction to a food when you introduce it?

Call 911 immediately if your child has a severe allergic reaction. “In babies, sometimes low blood pressure—another sign of a serious allergic reaction—takes the appearance of the baby being lethargic or a ‘floppy’ feeling,” Marks-Cogan says. “These are signs of anaphylaxis, which is a form of allergic reaction that can only be reversed using epinephrine (an EpiPen). Antihistamines like Benadryl will not treat anaphylaxis.”

Can children outgrow a food allergy?

In her experience, the most common allergy in infants is cow’s milk. The good news: About half of children will become tolerant or “outgrow” this allergy by age five. Hen’s eggs are the second most common allergy, and about half of children will outgrow this allergy by age six. As for peanuts, this allergy is more persistent, with only about 20 percent of children outgrowing their peanut allergy by age eight. 

“Food allergies that persist into later childhood and teenage years are much more likely to be persistent throughout life,” Marks-Cogan says. “It’s important to remember that even though many kids outgrow milk and egg allergies, they still make up a significant proportion of adult food allergies and a significant number of severe food allergic reactions.”