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Allergens
can be passed from mother to baby
Protein from peanuts ingested by lactating mothers is secreted into breast
milk, and exposure to peanut protein during breast-feeding may sensitize
babies at risk of peanut allergy, according to an article in The Journal
of the American Medical Association (JAMA).
Peter Vadas, M.D., Ph.D., of St. Michael’s Hospital, University of
Toronto, Ontario, and colleagues conducted a clinical investigation at
two North American hospitals from March 1999 to October 2000 to find out
if maternal dietary peanut protein passes into breast milk during lactation.
The authors tested breast milk samples from 23 healthy, lactating women
aged 21 to 35 years.
According to background information cited in the article, peanut allergy
is a significant public health problem. Approximately 1 percent of
British and U.S. preschool children are sensitized to peanuts.
It starts early in life, is often associated with severe or life-threatening
reactions, and is rarely resolved. Peanuts account for the majority of
food-induced anaphylactic fatalities. Between 72 percent and 81 percent
of individuals who have reactions to peanuts do so on their first known
exposure. Since IgE (an antibody) -mediated allergic reactions require
prior exposure resulting in sensitization, earlier peanut exposure must
have been hidden in most cases. Potential but unproven routes of hidden
exposure include exposure in the womb and exposure to peanuts transferred
from maternal diet via breast milk during lactation.
The authors collected breast milk samples from women who avoided ingesting
legumes (peanuts, beans, peas) for 24 hours, and fasted overnight.
The women then consumed 50 grams (approximately one half cup) of dry
roasted peanuts. Samples of breast milk were collected at 1, 2, 3, 4, 6,
8, and 12 hours after peanut ingestion. The authors measured the
presence in breast milk of total peanut protein and two major peanut allergens.
“Peanut protein was detected in 11 of 23 subjects. It was detected
in 10 subjects within two hours of ingestion and in one subject within
six hours,” the authors write.
“The median [middle] peak peanut protein concentration in breast
milk was 200 nanograms per milliliter. Both major peanut allergens
[also] were detected,” they continue.
“Peanut proteins have long been suspected to be secreted but have never
been identified in breast milk. We now provide definitive evidence for
secretion of peanut protein into breast milk of lactating women,” the authors
assert.
“Peanut protein concentrations found in breast milk ranged from
120 to 430 nanograms per milliliter, comparable with the levels of beta-lactoglobulin
[cow’s milk allergen], ovalbumin [egg allergen], ovomucoid [egg allergen],
and gliadin [dietary wheat allergen] detected in breast milk,” they continue.
The authors point out that several studies have documented an epidemiologic
relationship between increased consumption of peanuts by pregnant and breast-feeding
mothers and the likelihood of allergic sensitization of their children.
“These studies, in conjunction with our data, suggest that transfer
of maternal dietary peanut protein to breast milk may predispose at-risk
children to occult sensitization,” they conclude.
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