Breast-feeding has been shown to
result in both short- and long-term
benefits with regard to health and
cognitive development and a reduced
risk of diabetes, obesity, and
cardiovascular disease. Many of
these benefits have been associated
with bioactive proteins in breast milk
. Among these bioactive proteins
are lactoferrin, α-lactalbumin, and
milk fat globule membrane (MFGM)
Lactoferrin is an iron-binding protein
and a major constituent (10–20%)
of the protein in breast milk. It is
known to inhibit the growth of, or kill,
potentially harmful bacteria and has
anti-inflammatory activity in the gastrointestinal
tract of breast-fed infants
. Lactoferrin has a very stable structure
and is therefore relatively difficult
to break down; in fact, intact lactoferrin
is found in considerable amounts
in the stool of breast-fed infants . It
can be taken up by human intestinal
cells and is capable of binding to the
nucleus of the cell . There, it can
affect the expression of various genes,
which most likely explains its effects
on the immune system and on cellular
growth and proliferation.
α-Lactalbumin is also a major protein
(15–20%) in human milk. During
its digestion in the gastrointestinal
tract of breast-fed infants, peptides
are released that, in turn, have been
to have biological activity.
Among these peptides are an immune-
stimulating peptide, peptides
enhancing the absorption of essential
micronutrients such as iron and zinc,
and peptides that have prebiotic activity,
i.e. that stimulate the development
of a beneficial gut microflora .
MFGM proteins are associated
with the lipids in milk and are very diverse
in composition and function .
They have been shown to have both
anti-bacterial and anti-viral activities.
Human milk MFGM proteins have
been shown to bind to various rotavirus
strains and prevent replication, an
ability that was associated to a specific
protein, namely lactadherin .
Further, the concentration of lactadherin
in breast milk was shown to be
negatively correlated to rotavirus infection
in Mexican infants .
Breast milk contains a multitude of
bioactive proteins, but the concentrations
of the above-mentioned proteins
are particularly high. They are, however,
also present in cow’s milk, albeit
at considerably lower concentrations.
Thus, if they could be enriched
and concentrated, they can possibly
be added to infant formulas. However,
as they are somewhat different in
structure from their human milk counterparts,
it is important to evaluate if
they can provide any of the bioactivities
of the breast milk proteins. Such
tests need to be done in the research
laboratory, and if successful, clinical
trials on human infants will be required.