The Duchess of Cornwall's mother lost about eight inches in height after developing osteoporosis, and became so bent over she was unable to digest her food properly before she died in 1994 aged 72.
Camilla told an audience at Government House in Melbourne:
I watched my mother and grandmother die of this disease and no one knew what this disease was.
But since then the research has gone from strength to strength and they've made huge strides in the UK as you are here [in Australia].
To unite with all of you today is so important, to get the message worldwide to people that it can be prevented.
Prince Charles has celebrated his 64th birthday by going behind the scenes at the new Hobbit film.
The Duchess of Cornwall cradled an orphaned kangaroo joey in her arms as the Royal Jubilee tour arrived in the Australian Outback.