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Persistence of Human Milk Proteins in the Breast‐Fed Infant
Author(s) -
DAVIDSON LAURIE A.,
LÖNNERDAL BO
Publication year - 1987
Publication title -
acta pædiatrica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 115
eISSN - 1651-2227
pISSN - 0803-5253
DOI - 10.1111/j.1651-2227.1987.tb10557.x
Subject(s) - lactoferrin , feces , lysozyme , breast milk , excretion , albumin , breast feeding , infant formula , immunoglobulin a , immunoelectrophoresis , medicine , endocrinology , physiology , biology , immunology , antibody , microbiology and biotechnology , food science , biochemistry , immunoglobulin g , pediatrics
Several proteins in human milk are postulated to have physiological functions in the breastfed infant. Therefore, survival of human milk proteins after passage through the gastrointestinal tract of the breast‐fed infant was investigated. Fecal samples were collected from exclusively breast‐fed term infants and milk samples from their mothers. Soluble proteins in the feces were extracted and analyzed for total protein, nitrogen, lactoferrin, secretory IgA, serum albumin and lysozyme. Significant amounts of lactoferrin and secretory IgA were excreted by the infants and this excretion decreased throughout the study period in a trend similar to the decreasing milk concentrations of these proteins. Gel filtration demonstrated excreted lactoferrin and secretory IgA to be intact. No serum albumin or lysozyme was detected in the fecal extracts. Crossed Immunoelectrophoresis showed three human milk proteins to be present in the feces—the third was identified as α 1 ‐antitrypsin. Excretion of these proteins indicates the total protein content of human milk is an over‐estimation of the protein nutritionally available to the infant.