Elisheva wrote:

"But since human milk so readily separates, and the fat so readily adheres
to
the bottle, some kind of swirling or something seems necessary to get it all
out, no?
Does swirling have the same denaturing effect?  Do we know how hard you have
to be shaking it to do damage to those molecules?"

I think that there are probably two (maybe three) mechanisms at work when it
comes to shaking breastmilk. The first being the pure mechanical stress of
the shaking and constituents i.e. the cells and the large molecule 'banging
together'. The second is that when you shake milk vigorously you get small
bubbles. From my previous experience (as a research biologist) working with
blood, bubbles would cause all sorts of cascades (platelet aggregation etc).
Bubbles in blood (whether its still in your circulation or not) cause
problems - eg. divers and the "bends" or people on coronary bypass circuits
(the bubble oxygenator type). There's just something about the surface of a
(micro)bubble that get cells and proteins all wound up.
The third is that the milk is not in its physiological enviroment - again
don't have any research to back this up but breastmilk is a living product,
just like blood.

I think that GENTLY warming and swirling a bottle of breastmilk has too be
weighed against the fact that much fat sticks to the bottle wall (certainly
my own experience) and the fact that if you just leave the fat stuck to the
wall then its not going to get to the baby. Even if some of the consituents
are damaged, a bottle of expressed breatmilk is still going to contain AT
LEAST one more immune cell or one more growth hormone molecule that
artificial baby milk.

Just my ideas - has any research been done on this i.e. the swirling and
shaking and NOT the warming?? I know, I'll need to check the archives, books
and medline!

Yours

Sara Bernard
Who's becoming hooked on the biochemistry of breastmilk.
(lay bf counsellor intraining (Vereniging Borstvoeding Natuurlijk, The
Netherlands)

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