Source—United States Breastfeeding Committee

Claire K. Dalidowitz, Connecticut, USA

Peanut allergy is a complex medical issue involving many factors such as family history, genetics, ethnicity, environmental influences, baby’s health and development. Claire Dalidowitz is a member of LLLI’s Health Advisory Council (HAC) and in this article she summarizes current research and recommendations for reducing the risk of peanut allergy. Leaders are not medical professionals and as such, can not give advice about peanut allergy or any other medical condition. Leaders can share general information with parents who may be concerned about peanut allergy and encourage them to discuss any concerns with their baby’s health care provider. 

Incidence of peanut allergy

Peanut allergy affects 1.4% to 5% of people depending on their global location. Peanut allergy generally presents at around 18 months of age but can occur sooner or later. From 1997‑2008, peanut allergy increased 11% in developed countries (Savage 2016). Food allergy is influenced by both parental genetics and environmental influences.

Health risks

Peanut is one of the allergens that can cause more severe reactions and a higher risk of an  anaphylactic reaction causing throat swelling and breathing difficulty. Peanut allergy is less likely to be outgrown than other allergies. In one study, only 22% of children with a confirmed peanut allergy outgrew it by four years of age (Peters, 2015).

Peanuts and pregnancy

In the past, dietary avoidance of peanut during pregnancy was thought to be the best way to avoid peanut allergy. However, this has not been shown to decrease peanut allergy. One study with 8059 non-allergic pregnant mothers who consumed peanut more than five times per month had infants with significantly less peanut allergy than mothers consuming peanut less than once per month (Miles, 2015).

Peanut transfer to breast milk

Peanut protein (Ara h 6) has been shown to transfer to breast milk within ten minutes after consumption of one ounce (30 g) of peanut protein. The amount in breast milk peaks after one hour but peanut protein can still be detected over a 24 hour period. A study with mice showed that immune complexes IgA and IgG (peanut allergen complexes) are also secreted and led to partial oral tolerance (Bernard 2014). Restricting peanut while breastfeeding is not recommended as it does not prevent peanut allergy (Boyce, 2011)(Kramer, 2012).

Introduction of peanut

In 2000 the American Academy of Pediatrics (AAP) published recommendations to prevent food allergy in infants at risk for allergic disease. It was recommended that peanut introduction be delayed until age three years if there was a history of atopy (allergic symptoms) such as food allergy, atopic dermatitis (eczema) or if there was atopy in two or more first-degree family members (Gupta, Sicherer 2017). During the next decade, the incidence of all allergies increased however. As a result, the AAP re-examined their recommendations and in January 2008 stated that there was no convincing evidence to delay allergenic foods. Agreement came from  other professional groups including the European Society for Pediatric Gastroenterology, Hematology and the Nutrition Committee and the Section on Pediatrics of the European Academy of Allergology and Clinical Immunology (Fleischer, 2013).

In 2015, a study on the introduction of peanuts called the LEAP study (Learn Early About Peanuts) was published in the United Kingdom. Infants at high risk for allergy were given small amounts of peanut products three times per week. The relative risk of peanut allergy, when compared to a control group restricting peanut, declined 80% if introduced between four and 11 months of age (Du Toit 2015, Fleischer, 2015). In another subsequent study EAT (Enquiring About Tolerance) multiple allergens were given to breastfed infants at three months of age. When the data was analyzed, there were no cases of peanut allergy among the 310 infants who had early introduction of peanut and 13 cases of peanut allergy in those (525 infants) who introduced peanut per parental discretion after six months (Perkin  2016). The amounts of solid food being discussed in connection with peanut allergy trials are very small and can be considered as tastes or “therapy” rather than introducing large amounts of solid food.

Effect on breastfeeding

Most professional groups recommend exclusive breastfeeding for six months. World Health Organization (WHO), American Academy of Pediatrics (AAP), UK’s National Health Service and the Canadian Pediatric Society (CPS), all recommend exclusive breastfeeding for six months due to its nutritional benefits and protection against disease. The Womanly Art of Breastfeeding (p249) explains that introducing solids around the middle of the first year ties in with the arrival of the baby’s own digestive enzymes and their developmental readiness. Will new research on allergy prevention, especially peanut, mean new recommendations for infants who are at high risk for peanut allergy?

Best Practice

An important study that supports breastfeeding in preventing peanut allergy is the Canadian Asthma Primary Prevention Study (CAPPS). Convincing evidence from this 1994 Canadian study found that the best reduction in peanut allergy occurred when the breastfeeding mother consumed peanuts while breastfeeding and introduced a peanut product to her infant before 12 months of age. It is thought that the passive transmission of peanut allergens in the breast milk along with the maternal immunomodulatory factors in the milk, primes the infant’s immune system to develop tolerance to peanut when it is introduced later (Pitt, 2017). Although there is some evidence for early peanut introduction, there is no convincing evidence for early introduction of other foods (Gupta 2017). Further research on other allergens is in process which will provide more guidance to breastfeeding mothers in the future.


Recommendations for introducing peanut to a baby’s diet varies in different parts of the world.


The Scientific Advisory Committee on Nutrition (SACN) and the Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) produced a recent statement: Assessing The Health Benefits And Risks Of The Introduction of Peanut And Hen’s Egg Into The Infant Diet Before Six Months of Age In The UK, SACN-COT, 2018 which recommends introducing peanut alongside breastfeeding between 6-12 months of age. After which time, if well tolerated, it should continue to be included in the diet. For babies at high risk of allergy, medical advice can be sought before introducing allergenic food.


The National Institute of Allergy and Infectious disease published an addendum to their 2010 recommendations. It recommends that:

  1. Infants who have severe eczema or those with an egg allergy are at high risk for peanut allergy.
    • Screening for peanut allergy with a skin prick test or serum blood test to only peanut should be conducted. Other food allergens should not be tested as they may give false positive results which would result in unnecessary restriction of food.
    • If IgE (Immunoglobulin E) blood levels (a marker to measure allergy) are <0.35 KU/L, peanut can be introduced between four and six months of age, under the care of a food allergist who will also evaluate if the baby is developmentally ready to eat solids. The amount of peanut protein to be introduced is very small (two grams, with a total of six grams per week).
    • If the IgE level is >0.35 KU/L a food allergist should be contacted to help with the assessment.
  2. Infants with mild to moderate eczema should start peanut products at around six months of age.
  3. Those with no history of eczema or food allergy can start peanuts as part of complementary foods during the second six months of life in accordance with family and cultural practices (Togias, 2017).


Developmental oral-motor readiness is important when solid foods are introduced. A pureed type baby food could be introduced first to assess the ability of the infant to consume a more solid food. Soft peanut products are available for infants because peanuts themselves and peanut butter are a choking hazard. Options are thinned smoothed peanut butter (add breast milk), peanut butter powder (with breast milk), smooth peanut butter puree (thinned with breast milk) (Gupta 2017). The purpose of this introduction is to allow the infant’s immune system to adapt to the peanut protein. The quantity given is quite small and is not to be considered as a meal or a supplement.

If a sibling has a confirmed peanut allergy, there is a 7% likelihood that the infant may have the same allergy. Some parents may want a food allergy evaluation  by a food allergist before introduction (Fleischer, 2013).


The Philippine Society of Allergy, Asthma and Immunology published guidelines for allergy prevention and these recommend peanut introduction at 4-11 months (Recto, 2017).

Middle East and North Africa

In a study on physician practice in food allergy prevention in the Middle East and North Africa, 62.5% recommend postponing introduction of allergenic foods despite current research (Vandenplas, 2017).


Allergen introduction may not be able to be generalized to all populations. In Singapore, mothers of Chinese, Malay and Indian ethnicity introduced peanut at a mean age of 19 months. No significant associations were found between this timing and increased food allergy and in fact the incidence was low. Peanut allergy is rare in this population. (Tham, 2017).

Ongoing Research

Research is ongoing to find other potential ways to prevent the development of food allergy such as the use of probiotics and vitamin D (Fiocci, 2015 and Yepes-Nunez, 2016).  Other studies have looked at fish consumption by the mother, omega three fatty acids, ratio of omega six to omega three fatty acids, child’s antioxidant status, and exposure to cigarette smoke and other pollutants (Netting, 2014). Results so far are inconclusive.

Oral Immunotherapy is now being used with older children to diminish the reaction to peanut ingestion. This is used with those who have a confirmed peanut allergy. It involves desensitization by the giving of tiny amounts of peanut protein with increasing doses as tolerated. The benefit of this therapy is that children may tolerate accidental ingestion of small amounts of peanut protein without reaction (Factor, 2012). Oral immunotherapy should only be undertaken with strict medical supervision.


Food allergy and the accompanying atopic diseases asthma, rhinitis, and atopic dermatitis are complex and appear to be multi-factorial. There is some research to support the early introduction of peanut, especially in infants with severe eczema. There is also research to say that all infants should have peanut introduced before 11 months of age (Du Toit 2015; Fleischer 2015). In the non-Asian population, there is, however, support for breastfeeding, consumption of peanuts in the mother’s diet and introduction of peanut to the infant before 12 months (Pitt, 2017), suggesting that both breastfeeding and timing of peanut introduction are important. Parents will need to consult with their health care provider for individualized recommendations for introducing peanut to their child’s diet.

Folllow up research has not shown that early introduction of peanut will prevent other allergic diseases such as asthma, eczema, or tree allergies suggesting that factors for other allergic diseases are genetic or environmental and are distinct from peanut allergy (Du Toit, 2017).

Summary of Recommendations for Allergy Prevention

Eating peanuts during lactation promotes the passage of immunomodulatory factors (factors that modify the immune system) into breast milk which helps babies tolerate peanut when it is introduced before 12 months of age. Recommendations for the timing of introduction of peanut to a baby’s diet varies across the world. Parents of infants at high risk of allergy should check with their health care professionals for the latest recommendations in their area and to enable the health professional to guide and supervise the introduction of the peanut product on an individual basis (Togias 2017). All other infants should be exclusively breastfed until six months, when, after successful introduction of some complementary food, a peanut product can be added. Some families may want further evaluation before introduction (Sicherer, 2017).

AAP has retracted their prior recommendations to restrict the major food allergens until after one year of age.

Don’t restrict peanuts during pregnancy in the maternal diet

Don’t restrict peanuts in the mother’s diet during lactation

Do introduce very small amounts of peanut before 12 months

Do continue breastfeeding during the time of introduction as this reduces the possibility of reaction to an allergen

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Claire K. Dalidowitz MS, MA, RD, CD-N is a registered dietitian who counsels food allergic children and their families at Connecticut Children’s Medical Center as well as serving as the dietitian for the Food Allergy Clinic at the hospital. She is an adjunct professor at the University of New Haven where she teaches graduate level maternal and child nutrition. Claire has recently completed the food allergy guidelines and teaching material for the Pediatric Nutrition Care Manual for the American Academy of Nutrition and Dietetics. Claire’s interest in lactation goes back many decades where her master’s research focused on the lactation outcome of mothers with insulin dependent type 1 diabetes. She was instrumental in starting the lactation committee at Connecticut Children’s Medical Center and developed many of their breastfeeding policies. Claire chaired the national practice group (of the Academy of Nutrition) on Women and Reproductive Nutrition, served as secretary on the International Board of Consultant Lactation Examiners(IBLCE) and currently is a member of the Health Advisory Committee of LLLI.
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