Does Breastfeeding Affect Allergies?

baby breastfeeding black and white

As anyone who’s had a baby in the last 15 years will tell you, the push to breastfeed is intense. It’s a topic that comes up often before you even conceive with a steady drumbeat all the way through pregnancy, delivery, and throughout the first year.

Among the ever growing list of benefits to breastfeeding, the most commonly discussed is benefit for the baby’s immune system. Regardless of your decision or ability to breastfeed or not, one thing is not so clear: how does breastfeeding, and what you eat, impact your growing baby’s tolerance to food allergens?

With conflicting studies, it’s hard to know for sure. But here is what we do know. Breast milk is unique to each mother, and what’s in the breast milk can have an effect on the baby’s immune system, gut bacteria, and more.

Is it Who You Are?

One study showed that breastmilk consumed by babies who ended up with a cow’s milk allergy (CMA) had different types of milk sugars, and different amounts of cytokines and IgA. The milk sugars in the babies without CMA are thought to feed gut bacteria that strengthens the gut lining, and the IgA affects the immune response. (This study was sponsored by Prolacta, which sells a human milk based formula for neonates.)  

Unfortunately, the makeup of breast milk insofar as sugars and immune elements go, is largely predetermined by the mother’s own immune system, gut bacteria, and environment. So there’s not much a mother can do to change it.

Or is it What You Eat?

On the other hand, some elements of breast milk are affected by what a mother eats. For example it has been shown that in about 40% of women, peanut proteins were detectable in the expressed breastmilk one to two hours after peanut consumption. Another study of breast milk showed that you could change the average levels of fatty acids, and some immune elements by supplementing with fish oil.

Or is it a Little of Both?

Studies dating back to the 1970’s all the way through today show that there isn’t a difference in allergy rates between children who are breastfed, given cow’s milk formula, or soy formula.

The biggest predictor of allergies is the presence of allergy in the parents. Which probably means that the elements of breast milk that we can’t really control today have more to do with allergy rates than the temporary changes caused by a mother’s diet.

Lastly, though scientists used to think the breast milk could sensitize a baby to a food allergy, they now believe it’s more likely environmental exposure which sensitizes a baby.


Based on the latest scientific studies, we can say that eating allergenic foods while pregnant or nursing probably has no real effect on allergy rates, but it doesn’t hurt either. 

The one thing that has definitively been proven by science is that providing allergenic food regularly once your baby starts eating, definitely helps.

So don't worry about what you're eating during pregnancy or while breastfeeding when it comes to food allergies. The biggest steps to take are once your baby starts eating solids. 


A Few Quick Definitions

Cytokines: Cell signalling molecules that aid cell to cell communication in immune responses and stimulate the movement of cells towards sites of inflammation, infection and trauma.  

IgA: IgA immunoglobulins are present in mucus membranes and help fight bacteria and viruses. IgA increases in response to foods when the foods we eat cause inflammation, and in response to stress, disease, or alcohol.

CMA versus Lactose Intolerance: “CMA involves the immune system, babies who are allergic to cow’s milk protein will also show allergy symptoms--itchy rash, wheezing, or runny noses and coughs. These aren’t seen in lactose intolerance, as this condition doesn’t involve the immune system.

Another difference is that with cow’s milk allergy, even a small amount of cow’s milk protein could give your baby an allergic reaction. In contrast, many people with lactose intolerance can often eat small amounts of milk products without noticing any symptoms.”




Lil Mixins is the #1 selling Infant Peanut Powder and Infant Egg Powder, helping moms around the country start early introduction of peanuts and other allergens to their infants and babies.

Learn more about food allergies and your child on our About Page, in our Parent Resource Center, and our FAQ

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