Study suggests that eating peanut while breastfeeding may help protect against peanut allergy in children

A new study, published in the Journal of Allergy and Clinical Immunology (JACI) in September 2017, indicates that infants whose mothers ate peanut while breastfeeding, and who were introduced to peanut by 12 months, may have a lower risk of developing a peanut allergy later in childhood.

Led by researchers at the Children’s Hospital Research Institute of Manitoba and the University of Manitoba, the study found that the lowest rate of peanut sensitization was among children whose mothers ate peanut while breastfeeding and directly introduced peanut before 12 months.

Many of you had questions about this study and we recently had the opportunity to interview two of the authors of the study, Dr. Meghan Azad and Dr. Tracy Pitt, about their findings. Below are their responses to the top 10 questions we received from our readers:

1. Can you explain a bit more about how this study was conducted? Who was studied and what was the sample size?

We analyzed data from the Canadian Asthma Primary Prevention Study (CAPPS), which began in 1995. The study enrolled pregnant women in Winnipeg and Vancouver with an immediate family history of asthma or allergic disease. Women were randomly assigned either to a multifaceted intervention for asthma prevention (this included advice for mothers and infants to avoid peanut consumption), or to a control group.

[Editor’s note: A control group is the group in the study that does not receive treatment by the researchers and is used to compare with the group who did receive the treatment.]

Mothers reported on their peanut intake and infant feeding practices, and their infants were followed over time to examine if they developed asthma or other allergic conditions, including sensitization to peanut. There were 545 families enrolled into the study, of which 342 were successfully followed until 7 years of age.

2. What was the motivation behind the study? What were you aiming to learn?

Recent studies have shown that early introduction of peanut may help prevent (rather than cause) peanut allergy. However, these studies did not account for maternal peanut consumption or breastfeeding, yet we know that peanut protein can be transferred in breast milk. Using data from CAPPS, we examined how breastfeeding, maternal peanut consumption, and the timing of peanut introduction are related to the development of peanut sensitization.

3. What should parents take away from this study? What do you hope they learn from it?

Our results suggest that peanut exposure through breast milk combined with direct peanut introduction in the first year of life may decrease the risk of peanut sensitization by age 7 years. Further studies are needed to confirm these results, but in the meantime mothers are encouraged to breastfeed and follow current guidelines for peanut introduction.

[Editor’s note: Click here for more information on the guidelines for the introduction of peanut to babies, including recorded webinars for parents and healthcare professionals, and an FAQ document for parents.]

4. How would you explain instances of peanut allergy where mothers confirm that they ate peanuts while pregnant and breastfeeding?

Allergies are complex, involving many factors. We do not have enough evidence to definitively relate peanut allergy with maternal peanut ingestion in any one family. Studies such as ours address relative risk. For example, every time we cross the road there is a risk of being hit by a car. Looking both ways significantly decreases this risk, but does not completely eliminate the risk.

5. What could explain parents who avoided peanuts, perhaps due to their own peanut allergy, who have children without allergies?

As noted above, we cannot control for every variable for every family in these studies. More studies are still needed to examine if a child’s tolerance to peanut is related to avoidance of peanut by one or both parents in the home. We are getting closer to personalized advice, but for now the best we can do is recommend what seems best for most families.

6. Will the combination of consuming peanuts while pregnant and nursing with early introduction of peanuts to infants ensure children in the future do not develop peanut allergy?

Our results suggest that this combination of exposures may help prevent peanut allergy in future generations, but we cannot conclude this for certain until further research is done to prove a cause-and-effect relationship in the general population. Again, as noted, there are no guarantees for any one family.

7. Some parents feel this study blames the mother for her child’s peanut allergy. How would you respond to that?

Mothers should not be blamed for their child’s peanut allergy. Allergies are multifactorial – meaning they are caused by a combination of genetic, environmental, and lifestyle factors. Research addressing all of these factors is needed in order to understand why allergies develop and how they can be prevented.

8. What does this study mean for parents of children who currently have a peanut allergy?

Our study is relevant to allergy prevention. It does not address treatment of existing allergies.

9. Is there additional research planned to expand on the results of this study?

We are currently studying breast milk to understand how it affects the infant immune system and allergy development. We also hope that other researchers will be motivated to replicate our study in different settings and populations to help validate the results. A clinical trial would be required to confirm whether maternal peanut consumption, breastfeeding and early peanut introduction can reduce the risk of peanut allergy.

10. Is there anything further about this study you would like to share?

This study brings us one step closer to understanding this complex process and could help prevent allergies in future generations. However, further studies are needed before any definitive recommendations can be made regarding maternal peanut consumption and breastfeeding in relation to peanut allergy.

Thank you Dr. Azad and Dr. Pitt! To read the research paper on this study, please click here.

We thank all the readers who commented and submitted questions when we published the news about this study. We appreciate your continued engagement.

About Dr. Azad and Dr. Pitt

Dr. Meghan Azad

Dr. Meghan Azad holds the Canada Research Chair in Developmental Origins of Chronic Disease. She is an Assistant Professor of Pediatrics and Child Health at the University of Manitoba and a Research Scientist at the Children’s Hospital Research Institute of Manitoba. Dr. Azad holds a PhD in Biochemistry and Medical Genetics, and completed postdoctoral training in Epidemiology and Pediatrics. Her research program is focused on the role of maternal and infant nutrition in the development and prevention of childhood obesity and allergic disease. Dr. Azad co-leads the Manitoba site of the Canadian Healthy Infant Longitudinal Development (CHILD) Study, a national pregnancy cohort following 3,500 children to understand how early life experiences shape lifelong health.


Dr. Tracy Pitt

Dr. Tracy Pitt is a Pediatric Allergist. She completed her undergraduate studies at McGill University in Montreal, medical studies at Howard University in Washington DC, Pediatric residency at New York Medical College in Manhattan, and Allergy and Clinical Immunology training in Winnipeg at the University of Manitoba, with a third year of training focused on Allergy research. She has been practicing Pediatric Allergy, Asthma and Clinical Immunology since completing her training with an evidenced based focus on anaphylaxis, allergic rhinitis, asthma, food allergy, along with idiopathic urticaria, and angioedema. She has published articles on asthma, idiopathic urticaria, egg allergy, and peanut sensitization.