When human milk samples were subjected to different storage and warming
regimens, the only one which dramatically reduced the antibacterial
qualities of the milk was microwaving.

Samples of expressed breast milk were used as a medium for culture of
e.coli.  They were subjected to the following treatments:
fresh; once-frozen and thawed at room temperature; once-frozen and thawed in
a 40 degree Celsius water bath; once-frozen and thawed (NOT warmed, just
thawed) in a microwave; and twice-frozen and thawed at room temperature.

Relative to using a laboratory culture medium, all the samples but one had
maintained a strong inhibitory effect on bacterial growth, nearly the same
as the fresh milk, with ten to twenty percent the amount of bacteria
appearing at the end of the culture period.  The one sample that had been
thawed in the microwave had four times the growth of lab medium, or about
twenty to forty TIMES the amount of bacteria in any of the other breast milk
samples.

This was a simple, SMALL test done in Norway and could very very easily be
replicated anywhere there is a microbiology lab and a lactating woman.

It seems that microwaving affects the immunoproteins in the milk, and not in
a good way.  If a baby gets one microwaved breast milk bottle and is
otherwise breastfed it probably isn't worth losing sleep over, as long as
the milk is allowed to stand long enough to be sure there are no hot spots.
But for babies living on EBM it makes a huge difference.  Seems like a good
idea to advise against microwaving EBM if it is to be used as baby food
afterwards.

This is the gist of what was published in our BF newsletter in Norwegian
early last year.  I am not up to translating all three pages this month.  It
is not a study, it is a test, but the results were unequivocal, and show
breastmilk to be a resilient immunoprotective fluid which can tolerate many
things, just not microwaving.

Rachel Myr
Kristiansand, Norway

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