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Human alpha-lactalbumin and bovine beta-lactoglobulin absorption in infants
M Kuitunen1, E Savilahti, A Sarnesto
1Children's Hospital, University of Helsinki, Finland.
Insights
Infant gut permeability to alpha-lactalbumin (ALA) and beta-lactoglobulin (BLG) decreases rapidly after birth. The infant gut may be transiently permeable to BLG when cow
Area of Science:
- Gastroenterology
- Pediatric Nutrition
- Immunology
Background:
- Infant gut permeability is a critical factor in nutrient absorption and immune development.
- Understanding the absorption of dietary proteins like alpha-lactalbumin (ALA) and beta-lactoglobulin (BLG) is crucial for infant health.
- Previous research has indicated potential permeability to cow's milk proteins in infants.
Purpose of the Study:
- To investigate the systemic absorption of human alpha-lactalbumin (ALA) and bovine beta-lactoglobulin (BLG) in infants.
- To determine the changes in gut permeability to these proteins from birth to 8 months of age or until weaning.
- To assess the transient permeability of the infant gut to BLG upon introduction of cow's milk formula.
Main Methods:
- A cohort of 20 infants was studied from birth to 8 months, maintaining a cow's-milk-free diet.
- Serum levels of ALA and BLG were measured using a sensitive immunofluorometric assay.
- Protein absorption was quantified relative to body weight and dose administered.
Main Results:
- Significant absorption of ALA was observed shortly after birth, decreasing rapidly by 2 months of age.
- Trace amounts of ALA were detected up to 8 months, with no significant difference in absorption between allergic and non-allergic infants.
- Bovine beta-lactoglobulin (BLG) was detected in serum after weaning, indicating transient gut permeability, particularly when cow's milk formula is introduced.
Conclusions:
- Systemic absorption of ALA and BLG occurs in infants, with ALA absorption being highest immediately after birth and declining sharply.
- The infant gut demonstrates transient permeability to BLG, especially upon initiation of cow's milk-based formula.
- These findings highlight the dynamic nature of infant gut barrier function and protein absorption.
Abstract:
We investigated gut permeability to human alpha-lactalbumin (ALA) and bovine beta-lactoglobulin (BLG) in 20 infants from birth to 8 months or until weaning, before which they were on a strictly cow's-milk-free diet. We measured the proteins with a sensitive, solid-phase, double-sandwich immunofluorometric assay. Median (range) levels of serum ALA on days 3-4 after birth, and at 1 and 2 months of age were 31 (12-225), 6 (0-55), and 2 (0-16) micrograms/l serum per g ALA given per kg body weight, respectively. At 3, 5, and 8 months of age, only trace amounts of ALA were found. One week after weaning, serum BLG was found in 5/13 infants (38%) and at 2 weeks in 3/14 infants (21%), with median concentrations of 7 and 4 micrograms/l serum per g BLG given per kg body weight, respectively. No ALA could be detected in any of these samples. In absorption of ALA, the four infants who had allergic symptoms did not differ from those without symptoms. Thus, systemic absorption of ALA and BLG does occur in infants. Absorption of ALA is greatest after birth, when 3 x 10(-4) (median) of the given antigens are absorbed, but absorption decreases rapidly. The gut may often be transiently permeable to BLG when cow's-milk-based formula is started.