Is There a Link Between Allergies and Breastfeeding?

Breastfeeding typically does not cause allergies or food sensitivities in babies. And though research suggests that exclusive breastfeeding may help delay or prevent some types of allergies (which has garnered the interest of many parents, particularly since the incidence of food allergies has risen dramatically in the past few decades), allergy risk is influenced by a mixture of genetic and environmental variables. Breastfeeding is just one part of the puzzle.

Allergies in Children

Babies and children can experience the complete range of allergic conditions, such as allergic rhinitis (hay fever), skin allergies (most common in kids 0 to 4), food allergies, eczema, asthma, and more.

Allergic reactions can be the result of immunologic changes in immunoglobulin E (IgE), an antibody formed by the immune system. They can also be non-IgE mediated, instead involving mast cells and basophils. Babies may come into the world predisposed to allergies, but they may not actually have reactions until they've had repeated exposure to an allergen. In some cases, an allergy might not become obvious until later in life.

Antibodies in Breast Milk

Breast milk contains five antibodies: Immunoglobulins A, D, G, M, and the aforementioned IgE. Each serves its own function to help the body stay healthy and avoid allergies.

While more research is still needed, some evidence suggests that passing these antibodies to a baby via breast milk may help reduce or prevent some types of allergies (particularly in babies with a family history), although it may have no significant effect on others.

What the Research Shows

Allergy studies are challenging to execute on account of many factors — food introduction, genetic factors, and maternal diet being the most significant. But most studies authenticate that exclusive breastfeeding (even as little as one month) can lessen how often some allergies occur.

Evidence also suggests that exclusive breastfeeding during the first four months may offer protection against certain types of allergic diseases including cow's milk allergy and atopic dermatitis.

Other notable findings suggest:

• Breastfeeding may "boost" a baby's immune response. In one mouse study, for example, researchers found that a mother's milk contains complexes of food proteins that are then combined with her antibodies. This combination is then passed to the breastfeeding infant through breast milk. The infant's immune system then takes up these protein-antibody complexes, which triggers the baby's immune system to produce cells that help protect against allergic reactions. A similar process may also take place in human mothers and children, although further research is needed.
• Breastfed infants may be less likely to develop eczema. Exclusive breastfeeding or breastfeeding and supplementing with a hydrolyzed infant formula has been shown to reduce the risk of eczema.
• Breastfeeding may not reduce the risk of asthma. In a large-scale study published in the Journal of Allergy and Clinical Immunology, researchers looked at data from over 330,000 British adults. Based on self-reported information, the results suggested that breastfeeding as a child did not play a role in preventing asthma and hay fever later in life.
• Avoidance diets do not prevent allergies. In the past, breastfeeding women were sometimes cautioned to avoid consuming foods that were commonly associated with food allergies including peanuts, eggs, milk, soy, wheat, nuts, and shellfish. More recent research has shown no association between maternal exclusion diets and the prevention of allergies.

Can Allergens Be Passed Through Breast Milk?

It is rare for a breastfeeding child to experience an allergic response to something passed through a mother’s milk.

The most likely suspect, when this does occur, is a response to cow’s milk in a mother’s diet. While only trace amounts of proteins from cow’s milk are passed to the child through breast milk, in rare cases, it may trigger an allergic response in the breastfeeding child.

Symptoms may include:

• Colic
• Incessant crying
• Unwillingness to feed
• Poor sleep patterns
• Acute diaper rash
• Vomiting
• Chronic diarrhea
• Eczema
• Hives
• Extreme paleness
• Colitis

A cow's milk allergy developing from exposure through a mother's breast milk is relatively rare, however, occurring in less than 1 percent of breastfed babies. If your child does experience any of the above symptoms, contact your doctor right away.

If it turns out that your baby is having a reaction to allergens passed through your breast milk and it is not possible to eliminate them, you might consider switching to formula. Be aware that you'll need to find one that is free of the allergen as well (for example, some formulas are derived from cow's milk).