The Australasian Society of Clinical Immunology and Allergy

MEDIA RELEASE 17 April 2001

A recent journal article highlights the importance of maternally-transferred allergens in sensitising young infants to various food proteins, especially the highly allergenic peanut protein. Another article of relevance to this issue is also included below.

1. Detection of peanut allergens in breast milk of lactating women. Vadas P,et al. JAMA 2001 Apr 4;285(13):1746-8

INTRODUCTION: Most individuals who react to peanuts do so on their first known exposure. A potential but unproven route of occult exposure resulting in sensitization to peanut is via breast milk during lactation.

OBJECTIVE: To investigate the ability of maternal dietary peanut protein to pass into breast milk during lactation.

DESIGN AND SETTING: Clinical investigation conducted at 2 North American hospitals from March 1999 to October 2000.

PATIENTS: Twenty-three healthy, lactating women aged 21 to 35 years.

INTERVENTION: Each woman consumed 50 g of dry roasted peanuts, after which breast milk samples were collected at hourly intervals.

MAIN OUTCOME MEASURES: Presence in breast milk of total peanut protein, analyzed by a sandwich enzyme-linked immunosorbent assay, and 2 major peanut allergens, Ara h 1 and Ara h 2, detected by immunoblot analysis.

RESULTS: Peanut protein was detected in 11 of 23 subjects. It was detected in 10 subjects within 2 hours of ingestion and in 1 subject within 6 hours. The median peak peanut protein concentration in breast milk was 200 ng/mL (mean, 222 ng/mL; range, 120-430 ng/mL). Both major peanut allergens Ara h 1 and Ara h 2 were detected.

CONCLUSIONS: Peanut protein is secreted into breast milk of lactating women following maternal dietary ingestion. Exposure to peanut protein during breastfeeding is a route of occult exposure that may result in sensitization of at-risk infants.

2: Immediate food hypersensitivity reactions on the first known exposure to the food.van Asperen PP,et al. Arch Dis Child 1983 Apr;58(4):253-6

We report 8 infants with immediate hypersensitivity reactions to foods (milk, egg, or peanut), occurring at the first-known exposure. Each developed symptoms within the first hour, but these generally settled within 2 hours. Sensitisation to the food concerned was demonstrated by positive immediate allergen skin prick tests in every case. Symptoms experienced included irritability, erythematous rash, urticaria, angio-oedema, vomiting, rhinorrhoea, and cough. Five infants were being followed prospectively and 4 were clinically tolerant of the food by age 16 months. The most likely route of sensitisation was via breast milk. None of the infants experienced similar reactions while being breast fed, suggesting that the reaction was dose dependent. As 5 out of a group of 80 infants being followed prospectively developed an immediate reaction at their first known exposure to a food, this appeared to be a not uncommon presentation of food hypersensitivity in infancy.