Marie Davis asks about the mechanism that makes cabbage leaves reduce
engorgement.
I wish we knew.  You quote Wendy Rosier's paper in a 1988 Breastfeeding
Review.  This was the very first paper published describing the use of
cabbage leaves.  The editor at the time hunted high and low for reasons that
could explain the phenomenon and got her explanation from a book on
naturopathic medicine.  It was a new thing in Victoria, although I heard it
was widely used in Western Australia.  The reasons suggested for why it
works are pure speculation, as much today as 7 years ago.
There is lots of clinical evidence that it works (on visiting my neighbour
who hails from Sri Lanka, I found she had made a shoe of cabbage leaves to
reduce the swelling in her ankle.  She told me it was an old Sri Lankan
remedy.  I astounded her by knowing about the use of cabbage leaves).
There are now proper studies that have tested the use of cabbage leaves, but
they still do not explain the how.  If you must have this for your document,
then you will have to leave the cabbage leaves out.
I feel very frustrated when people insist that they MUST have certain
information.  Sometimes it is not around simply because the research has not
been done as it is unethical or too hard or no one is interested in funding
it.  (This is not a dig at you, Marie, but my venting at the attitudes of
some people who contact me at the Lactation Resource Centre and insist on
answers to questions that to the best of my knowledge there are no answers
to yet.  My standard answer is 'please do the research and I will give your
answer to the next person who asks').
If someone else does come up with a definitive answer, I will be most
appreciative and will even eat humble pie for not knowing about it!
Philippa Thomson
Melbourne, Australia