Nitrogen and protein components of human milk

L. Hambraeus, B. Lonnerdal, E. Forsum, M. Gebre Medhin

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


The true protein content of human milk is 0.9%, in well-nourished as well as malnourished mothers. Casein constitutes only about 20% of the protein nitrogen in human milk. The remaining 80% is derived from the whey proteins, the 3 dominant components being α-lactalbumin, lactoferrin and secretory IgA. α-lactalbumin is a subunit of lactose synthetase. Lactoferrin is an iron-binding glycoprotein which plays a role in the defence against gastro-intestinal infections and is probably also involved in iron transport in the gut. Secretory IgA is comparatively stable at low pH; it is resistant to proteolytic enzymes and plays an essential role in the immunological defence against gastro-intestinal infections. Lysozyme is a minor component of the whey proteins and represents an active enzyme with a bactericidal effect. The nutritional and immunological significance of the marked differences with respect to the nitrogen and protein compositions of human milk and cow's milk should not be underestimated, but need further elucidation.

Original languageEnglish (US)
Pages (from-to)561-565
Number of pages5
JournalActa Paediatrica Scandinavica
Issue number5
StatePublished - 1978
Externally publishedYes

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health


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