by Anne Eglash MD, IBCLC, FABM

Does exposure to peanut protein in breastmilk reduce the risk of childhood peanut allergy? We know that when a mother eats peanuts, the peanut protein is present in her breastmilk. Waiting to introduce peanut, egg, and fish until one year of age was a previous recommendation by national pediatric and allergic societies starting in the 1990s, but this has been associated with increasing the risk of food allergy. It now seems clear that earlier exposure to highly allergic foods such as peanut, egg, and fish leads to a lower risk of allergy to these foods.

The question is, does exposure of peanut during breastfeeding count as early exposure, and do breastfeeding infants exposed to peanut in breastmilk have a lower risk of peanut allergy? Believe it or not, this has not been adequately addressed, nor studied, in the quest to figure out the best way to reduce the risk of childhood food allergies.

A group of Canadian researchers used data from the 1995 Canadian Asthma Primary Prevention Study, to explore the relationship between maternal consumption of peanuts during breastfeeding, timing of introducing peanut to their children, and risk of peanut sensitization at age 7. This was a study of 342 families with children who had been breastfed, who had a family history for asthma and other IgE-mediated allergic diseases.

What do you think the authors found regarding the relationship between peanuts in mother’s diet, timing of introduction of peanuts to their children, and the rate of childhood peanut allergy? Choose 1 or more:

  1. The lowest risk of peanut allergy occurred in children who were not exposed to peanuts during breastfeeding, and were not exposed to peanuts until 24 months of age.
  2. The lowest risk of peanut allergy occurred in children who were exposed to peanuts during breastfeeding and were given peanuts before 12 months of age.
  3. Children exposed to peanuts during breastfeeding had the same risk of peanut allergy whether they were fed peanuts directly before or after 12 months of age.
  4. Exposure to peanut protein during breastfeeding increases the risk of peanut allergy in all infants, no matter when they are fed peanuts directly.

See the Answer

Answers: B only. Not A, C, or D

Read the Abstract

Reduced risk of peanut sensitization following exposure through breast-feeding and early peanut introduction.

Pitt TJ, Becker AB, Chan-Yeung M, Chan ES, Watson WTA, Chooniedass R, Azad MB
J Allergy Clin Immunol. 2018 Feb;141(2):620-625.e1. doi: 10.1016/j.jaci.2017.06.024. Epub 2017 Sep 12.

Recent trials have shown that avoiding peanuts during infancy increases the risk of peanut allergy; however, these studies did not address maternal peanut consumption.

OBJECTIVE:
We sought to investigate the relationship between maternal peanut consumption while breast-feeding, timing of direct peanut introduction, and peanut sensitization at age 7 years.

METHODS:
Secondary analysis of a nested cohort within the 1995 Canadian Asthma Primary Prevention Study intervention study was performed. Breast-feeding and maternal and infant peanut consumption were captured by repeated questionnaires during infancy. Skin prick testing for peanut sensitization was performed at age 7 years.

RESULTS:
Overall, 58.2% of mothers consumed peanuts while breast-feeding and 22.5% directly introduced peanuts to their infant by 12 months. At 7 years, 9.4% of children were sensitized to peanuts. The lowest incidence (1.7%) was observed among children whose mothers consumed peanuts while breast-feeding and directly introduced peanuts before 12 months. Incidence was significantly higher (P < .05) if mothers consumed peanuts while breast-feeding but delayed introducing peanuts to their infant beyond 12 months (15.1%), or if mothers avoided peanuts themselves but directly introduced peanuts by 12 months (17.6%). Interaction analyses controlling for study group and maternal atopy confirmed that maternal peanut consumption while breast-feeding and infant peanut consumption by 12 months were protective in combination, whereas either exposure in isolation was associated with an increased risk of sensitization (P interaction = .003).

CONCLUSIONS:
In this secondary analysis, maternal peanut consumption while breast-feeding paired with direct introduction of peanuts in the first year of life was associated with the lowest risk of peanut sensitization, compared with all other combinations of maternal and infant peanut consumption.

Milk Mob Comment by Anne Eglash MD, IBCLC, FABM

Thank goodness for this article. I have been wondering about this issue for years. It seems that most of the large studies that evaluate timing of solids and risk of food allergies left out any information regarding the importance of allergen exposure during breastfeeding.

This study found that exposure of peanut protein during breastfeeding and being fed peanuts directly before 12 months of age leads to the lowest risk of peanut allergy (1.7%). An infant who is exposed to peanuts during breastfeeding but is not fed peanuts until after 12 months of age has a markedly higher risk of peanut allergy (15.1%). Children who are not exposed to peanuts in breastmilk but are fed peanuts directly before 12 months also have a higher risk of peanut allergy (17.6%). Therefore, according to this landmark study, it is the combination of exposure during breastfeeding and direct feeding of peanuts before 12 months that is most protective.

The authors point out that these findings need to be replicated before we can apply these principles to clinical practice. But I am all for sharing preliminary evidence

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