Eating allergenic foods and breastfeeding may help protect infants against food allergies

Food allergies often result in an abnormal immune response to certain types of food, whether it be peanuts, eggs, or gluten. Most reactions tend to be mild, typically resulting in itching and hives, but a severe allergy causes anaphylaxis, a serious allergic reaction that causes shortness of breath, low pressure, and tongue swelling.

It isn’t clear why some people develop food allergies and others don’t. However, new research from Boston Children’s Hospital has found that mothers who eat allergenic foods during their pregnancy as well as breastfeeding their child can protect them from food allergies.

Looking at pregnant mice

The study in question looked at pregnant mice that consumed allergy-provoking foods such as eggs and peanuts. It was discovered that these mice transferred protective antibodies to their offspring via their breast milk, which caused the baby mice to produce specific immune cells, making them tolerant to allergenic foods.

This finding rejects previously given advice telling mothers to avoid allergenic foods during pregnancy or while breastfeeding.

“Whether mothers should eat allergenic foods during pregnancy or avoid them has been controversial. Different studies have found different results, in part because it’s hard in human studies to know when mothers and babies first encountered a specific food. But in a mouse model, we can control exposure to food,” says Michiko Oyoshi, Ph.D., of Boston Children’s Division of Allergy and Immunology.

In addition to providing protection against food allergies, the production of other allergy-related immune cells (IgE and mast cell expansion) was also subdued. Additionally, the allergy protection provided by breast milk was seen to extend to unrelated offspring not exposed to food allergens in utero.

Mice fed human breast milk

Mice were also fed human breast milk with humanized immune systems, which are tailored to respond to human antibodies. Human breast milk was also found to provide a protective effect, which suggests that the result observed in this study may translate to human infants.

“We still saw protection from the in-utero exposure, but the protection was better when the mice were also exposed through breastfeeding. If you combine both in utero and breastfeeding exposure, you have optimal induction of food tolerance,” says Oyoshi.

Study to address effect in women and their offspring

Further studies plan to find out if this relationship holds true in breastfeeding human mothers. Breast milk samples will be taken, comparing milk from mothers whose infants are at high risk versus low risk for food allergies. This level of risk was assessed by looking at allergies in older siblings and by looking if the baby has early risk factors such as eczema.

While this study is currently underway, the researchers stress that eating peanuts or other allergenic foods may not guarantee a healthy baby, as genetic and environmental factors do play a role. However, they do recommend mothers eat every type of food to create antibodies to everything, which may give your baby the best chance against allergies.

Related: Maternal sensitivity found to increase the longer a mother breastfeeds