Detection of peanut allergens in breast milk of lactating women

Context 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.