Six infants suspected of food allergy during breastfeeding were evalua
ted using prick tests, total IgE, RASTs and intestinal permeability me
asurements during fast and provocation with mother's milk. An eliminat
ion diet was undertaken In mothers, removing first cow's milk protein
(CMP), then, when inefficient, all foods suspected on the clinical his
tory or a positive prick test in the child, followed by oral challenge
s in mother's diet with the corresponding food. The sole CMP-free diet
in mothers always proved insufficient. In four, an additional diet ex
cluding two to three other foods cleared the symptoms. Oral provocatio
ns in mother's diet with those foods were positive in all. In two, mot
hers turned down a diet excluding more than four foods, symptoms clear
ed while feeding the child with an extensively hydrolysed formula, whe
reas challenges with mother's milk induced immediate reactions. Intest
inal permeability was altered during provocation tests with mother's m
ilk sampled before maternal diet. Food allergy during breastfeeding ma
y be due to multiple foods and the inefficacy of the sole CMP eliminat
ion in mothers does not rule out food sensitization.